Pediatric/Exam/DES/USMLE

501. A mentally retarded 14-year-old boy has a long face, large ears, micropenis, and large testes. Chromosome analysis is likely to demonstrate which of the following?

502. A 5-month-old child with poor growth presents to the ER with generalized tonic-clonic seizure activity of about 30-minute duration that stops upon the administration of lorazepam. Which of the following historical bits of information gathered from the mother is most likely to lead to the correct diagnosis in this patient?

503. A 13-year-old girl presents with parental concerns of poor posture. She has not had any back pain. On examination, she has unequal shoulder height, asymmetric flank creases, and a forward-bending test that shows rib asymmetry. The physical examination is otherwise normal. Which of the following is the most likely cause of her condition?

504. After 10 days of nasal congestion and rhinorrhea, a 3-month-old infant develops a severe hacking cough during which he repeatedly turns dusky and appears to choke on or to vomit profuse thick, clear nasopharyngeal mucus. For 7 days, the coughing continues unabated. On physical examination, he is afebrile and his lungs are clear. His chest x-ray is normal. His WBC count is 24,000/mm3, with 15% polymorphonuclear cells, 82% lymphocytes, and 3% monocytes. Which of the following antibiotics should be used to treat this patient?

505. An 18-month-old boy presents with a history of fever to 39.0°C for 5 days. He has also been irritable and has not been drinking well. Associated symptoms include red eyes, a rash, and some trouble walking. On physical examination, he has a temperature of 39.5°C. He has bilateral bulbar conjunctivitis, a strawberry tongue, an inflamed oral pharynx, edema of the hands and feet, a morbilliform rash, and cervical lymphadenopathy. He is very irritable. His CBC shows a WBC of 15,000/mm3 with 60% neutrophils, 35% lymphocytes, and 5% monocytes. His hemoglobin is 12.0 g/dL and platelet count is 500,000/ mm3. Which of the following is the most likely diagnosis?

506. A 6 month old male is brought in to the Emergency Room by his mother who states that when she picked him up from the baby-sitter he was not acting right. The baby-sitter stated that he was sleeping more and was fussy. On examination the baby is stuporous. His temperature is 37.8 C (99.9 F), pulse is 140/min, and respirations are 36/min. A 4 cm ecchymosis is noted on his right cheek. The remainder of the physical examination is unremarkable. The physician suspects possible physical abuse. He orders a CT scan of the head, skeletal survey, chemistry panel and complete blood count. Which of the following diagnostic tests should also be ordered?

507. An infant is delivered at full term by a spontaneous vaginal delivery to a 29-year-old primigravida. At delivery, the infant is noted to have subcostal retractions and cyanosis despite good respiratory effort. The abdomen is scaphoid. On bag and mask ventilation, auscultation of the lungs reveals decreased breath sounds on the left, with heart sounds louder on the right. Which of the following is the most likely diagnosis?

508. A 12-year-old girl comes to the physician for an annual examination. She has been in good health for the past year and has no complaints. She began having menses this year and, after a few irregular cycles, is now having a monthly period. Past medical history is significant for multiple episodes of otitis media as a child. Past surgical history is unremarkable. She takes no medications and has no known drug allergies. Physical examination is unremarkable. If not currently immune, which of the following immunizations should this patient most likely receive?

509. A 4-week-old boy presents with a 10-day history of vomiting that has increased in frequency and forcefulness. The vomitus is not bile stained. The child feeds avidly and looks well, but he has been losing weight. An ultrasound of the abdomen is shown. Which of the following is the most likely diagnosis?

510. A 12-month-old girl has been spitting up her meals since 1 month of age. Her growth is at the 95th percentile, and she is otherwise asymptomatic and without findings on physical examination. Which of the following is the most likely diagnosis?

511. A 14-year-old girl has a 9-month history of diarrhea, abdominal pain (usually periumbilical and postprandial), fever, and weight loss. She has had several episodes of blood in her stools. Which of the following is the most likely diagnosis?

512. A 12-year-old girl complains of intermittent palpitations. She had previously been in excellent health and has met all development milestones. There is no family history of heart disease. She is on no medications and takes no drugs. She states that the palpitations begin and end suddenly and usually last a couple of hours. She is otherwise asymptomatic between episodes. The physical examination is normal. An ECG reveals a shortened PR interval and a slow upstroke of the QRS wave in lead III. Which of the following is the most likely diagnosis?

513. An 11-year-old boy is brought to the office by his mother because "he is sick." He has had headaches for the past several weeks, and has vomited 4 times in the past 5 days. He drinks large amounts of water and goes to the bathroom all the time. He is no longer interested in playing football and going out with his friends. His temperature is 37.0C (98.6F), blood pressure is 11 8/78 mm Hg, pulse rate is 84/min, and respirations are 16/min. On examination, there is loss of peripheral visual fields. His laboratory findings are as follows: W BC 7,800/mm3 Hemoglobin 12.6 g/dl Hematocrit 35% Platelets 199,000/mm3 Sodium 145 mEq/L Potassium 3.6 mEq/L Bicarbonate 24 mEq/L Blood urea nitrogen 18 mg/dl Serum creatinine 1.0 mg/dl Blood glucose 88 mg/dl X-rays of the head reveal a calcified lesion above the sella. What is the most likely diagnosis?

514. A 4-week-old male infant is brought to the office due to several episodes of projectile vomiting for the last few days. The vomitus contains milk and doesn't contain bile or blood. The child's appetite has increased for the last few days. He has been fed with goat's milk since birth, but doesn't seem to tolerate it anymore for the last few days. He vomits a few minutes after feedings. He appears dehydrated, and abdominal examination reveals no mass. Blood tests reveal macrocytosis. What is the most appropriate next step in the management of this patient?

515. A 6-year-old Hispanic boy is brought to your office by his mother because of severe pain in his right hip and refusal to walk for the last 2 days. His blood pressure is 100/70 mm Hg, pulse is 90/min, respirations are 18/min, and temperature is 38.7C (102.7F). His WBC count is 19,000/mm3 and ESR is 55 mm at one hour. On examination, he keeps his right hip externally rotated, and cries out in pain on any movement involving the right hip. Joint aspiration reveals a turbid fluid with total WBC: 90,000/mm3 and numerous bacteria. What is the most appropriate management in this patient?

516. A 6-week-old child arrives with a complaint of “breathing fast” and a cough. On examination you note the child to have no temperature elevation, a respiratory rate of 65 breaths per minute, and her oxygen saturation to be 94%. Physical examination also is significant for rales and rhonchi. The past medical history for the child is positive for an eye discharge at 3 weeks of age, which was treated with a topical antibiotic drug. Which of the following organisms is the most likely cause of this child’s condition?

517. A full-term neonate presents with hypotonia, lethargy and poor feeding over the past three hours. The pregnancy was uneventful, but during delivery, the neonate presented with shoulder dystocia and subsequently obtained a fracture of the clavicle. His Apgar scores are 7 and 8 at one and five minutes, respectively. His birth weight is 4000g. His vital signs are normal. Physical examination reveals an enlarged tongue, mild microcephaly, prominent occiput, prominent eyes and omphalocele. Abdominal palpation reveals an enlarged liver and kidneys. The initial work-up reveals hypoglycemia and hyperinsulinemia. What is the most likely diagnosis?

518. A 4-year-old child is brought to the emergency department after he ingested liquid oven cleaner. His vital signs are stable. He is crying and drooling with blood-tinged secretions. His lips and chin are swollen and erythematous. His clothes are contaminated with the material. His breathing appears normal. His lungs are clear. Based on these findings, what is the best next step in the management of this patient?

519. A male infant is born to a primigravid woman whose pregnancy was uneventful. The delivery was uncomplicated. Physical examination of the newborn reveals deformity of the feet, specifically adduction of the anterior aspect of the foot with a convex lateral border and concave medial border. The ankle movements are normal, and passive and active movement of the foot overcorrects the deformity into abduction. AP radiographs reveal mild adduction of the metatarsals at the tarsometatarsal articulation, and an increased angle between the 1st and 2nd metatarsals. What is the best next step in the management of this patient?

520. You are called to a delivery of a term infant, about to be born via cesarean section to a mother with multiple medical problems, including a 1-month history of a seizure disorder, for which she takes phenytoin; rheumatic heart disease, for which she must take penicillin daily for life; hypertension, for which she takes propranolol; acid reflux, for which she takes aluminum hydroxide; and a deep venous thrombosis in her left calf diagnosed 2 days ago, for which she was started on a heparin infusion. The obstetrician is concerned about the possible effects of the mother’s multiple medications on the newborn infant. Which of the following medications is most likely to cause harm in this newborn infant at delivery?

521. Your older sister, her husband, their 2-day-old infant, and their pet Chihuahua arrive at your door. The parents of the child are concerned because the pediatrician noted the child was “yellow” and ordered some studies. They produce a wad of papers for you to review. Both the mother and baby have O-positive blood. The baby’s direct serum bilirubin is 0.2 mg/dL, with a total serum bilirubin of 11.8 mg/dL. Urine bilirubin is positive. The infant’s white blood cell count is 13,000/μL with a differential of 50% polymorphonuclear cells, 45% lymphocytes, and 5% monocytes. The hemoglobin is 17 g/dL, and the platelet count is 278,000/μL. Reticulocyte count is 1.5%. The peripheral smear does not show fragments or abnormal cell shapes. Which of the following is the most likely explanation for this infant’s skin color?

522. A 14-day-old male infant is brought to the emergency department due to spasms involving the whole body. He has been having very poor suckling over the last couple of days. He was delivered vaginally by an untrained birth attendant, and his mother never sought any pre- or antenatal care. The pertinent physical finding is a swollen and erythematous umbilical cord. What is the most likely diagnosis of this patient?

523. A 4-year-old boy falls from the jungle gym at preschool. He sustains minor abrasions and contusions, and is taken care of by the school nurse. His parents take him that same afternoon to his regular pediatrician and demand "a thorough check-up" for possible internal injuries. The pediatrician complies, and a complete physical examination is normal. His hemoglobin is 14 g/dL, and a urinalysis shows the presence of microhematuria. Which of the following is the most appropriate next step in management?

524. A 9-year-old boy is brought to the pediatric clinic by his mother, who noticed that the left side of his mouth has started to droop over the past several days. In addition, he is unable to close his left eye completely and complains of it burning. Review of systems reveals a cold approximately two weeks ago and recent decreased taste sensation. Physical examination reveals a well nourished male with normal vital signs. There is left eye ptosis and mild erythema of the left conjunctiva. His smile is asymmetrical on the left. Laboratory evaluation, including a complete blood count and chemistry profile, are normal.Which of the following infections is most closely associated with this patient's condition?

525. A 5-year-old girl is brought to the physician with low grade fever and rhinorrhea. Her symptoms began ten days ago. She has also had persistent purulent rhinorrhea, nasal congestion, and a dry cough during the day that worsens at night. Her symptoms do not seem to be improving. On examination, the child has erythema and swelling of the nasal turbinates with purulent nasal drainage. She has evidence of drainage in the posterior pharynx as well. The remainder of her examination is unremarkable. Computed topography of her face is shown below. Which of the following is the most common predisposing factor for her condition?

526. A 1-week-old previously healthy infant presents to the emergency room with the acute onset of bilious vomiting. The abdominal plain film in the emergency department (A) and the barium enema done after admission (B) are shown. Which of the following is the most likely diagnosis for this patient?

527. A 3-year-old child presents to your office for an evaluation of constipation. The mother notes that since birth, and despite frequent use of stool softeners, the child has only about one stool per week. He does not have fecal soiling or diarrhea. He was born at term and without pregnancy complications. The child stayed an extra day in the hospital at birth because he did not pass stool for 48 hours, but has not been in the hospital since. Initial evaluation of this child should include which of the following?

528. A 3-month-old boy is brought to the pediatrician because of a red growth on his arm. The pregnancy had been uncomplicated, and the infant has been meeting all development milestones. He has been healthy so far and has received all scheduled immunizations. He is currently being breast-fed. His skin was clear at birth, but when he was 2 months old, his mother noted a light red growth on his arm. Within the past month, it has increased in size and has turned bright red. Which of the following is the most appropriate treatment for this disorder?

529. A 2-year-old boy is hospitalized for severe pneumonia requiring endotracheal intubation and mechanical ventilation. His hemoglobin level is 13.2 mg/dl and his WBC count is 3,200/mm3. The absolute level of CD3- positive lymphocytes is normal but the level of CD 19-positive lymphocytes is very low. This patient would benefit most from which of the following as a maintenance therapy?

530. A 14-year-old African-American boy presents to your office with difficulty walking for the past several weeks. He complains of pain in the right hip. He describes two episodes of severe hip pain and one previous episode of abdominal pain requiring hospitalization. Physical examination reveals motion restriction in the right hip joint. His joint is not erythematous or tender to palpation. His hematocrit is 22%. This patient's difficulty walking is most likely secondary to which of the following:

531. A 2-week-old boy in the neonatal intensive care unit had a birth weight of 1200 g. Ultrasound of the head reveals grade II intraventricular hemorrhage and periventricular leukomalacia. An ophthalmologic examination reveals retinopathy of prematurity of both eyes. In addition, a hearing screen demonstrates bilateral hearing deficits. Which of the following is the most important determinant of this child's neurodevelopmental outcome?

532. A 2-year-old girl is brought to her pediatrician by her parents because of increasing lethargy and irritability. She has just started walking, and is teething and likes to chew on the woodwork around the windows. Physicalexamination reveals a tender abdomen. Laboratory studies indicate high iron and ferritin levels. The peripheral blood smear shows basophilic stippling. Which of the following is the most likely diagnosis?

533. A 15-month-old boy is brought to the ER because of fever and a rash. Six hours earlier he was fine, except for tugging on his ears; another physician diagnosed otitis media and prescribed amoxicillin. During the interim period, the child has developed an erythematous rash on his face, trunk, and extremities. Some of the lesions, which are of variable size, do not blanch on pressure. The child is now very irritable, and he does not interact well with the examiner. Temperature is 39.5C (103.1F). He continues to have injected, immobile tympanic membranes, but you are concerned about his change in mental status. Which of the following is the most appropriate next step in the management of this infant?

534. The 3-year-old sister of a newborn baby develops a cough diagnosed as pertussis by nasopharyngeal culture. The mother gives a history of having been immunized as a child. Which of the following is a correct statement regarding this clinical situation?

535. A 10-hour-old newborn is noted to have a swelling in the scalp which was not present at birth. The swelling is limited to the surface of one cranial bone. There are no visible pulsations, indentations of the skull, or discoloration of the overlying scalp. What is the most likely diagnosis?

536. A 3-year-old boy is brought by his father to the Emergency Department with fever, headache and neck pain that developed over the past several hours. The father states he is not the birth father, and that he and his wife adopted the boy at 18 months of age after his birth mother abandoned him. Physical examination reveals a lethargic male with a temperature of 39.7 C (103.5 F). There is photophobia, and mildly injected conjunctiva are appreciated. Pupils are equal and reactive and funduscopic examination is unremarkable. The patient has neck stiffness with a positive Kernig's sign. A complete blood count reveals a leukocyte count of 24,000/mm3 with 64 segmented neutrophils and 25 bands. A lumbar puncture is performed that reveals elevated CSF pressure, decreased glucose, and elevated protein. A Gram's stain shows gram-negative pleomorphic rods. There is no growth on blood agar. Growth on chocolate agar reveals white colonies. Which of the following is the most likely pathogen?

537. A 16-month-old girl is brought to medical attention because of irritability, poor feeding, and temperatures up to 39.4 C (103 F). Careful history and physical examination fail to disclose any identifiable cause of her fever. There is some degree of abdominal tenderness on palpation. Which of the following is the most appropriate next step in diagnosis?

538. A premature neonate with respiratory distress syndrome is maintained on mechanical ventilation in a neonatal intensive care unit. Two weeks after delivery, the nurses in the intensive care unit notice that higher ventilation settings are needed and that more secretions are being suctioned from the endotracheal tube. A chest x-ray film shows questionable new infiltrates. Which of the following is the most likely pathogen?

539. A 2-year-old boy is brought to the emergency department (ED) in acute respiratory distress. He is afebrile, and has a heart rate of 100/min, respiratory rate of 80/min, and Sa02 of 84% on room air. He is sitting upright, and has significant nasal flaring and intercostal retractions. He is given supplemental oxygen in the ED. Chest x-ray reveal hyperinflation of the right lung, mediastinal shift to the left, and a severely hypoinflated left lung Which of the following is the most appropriate next step in management?

540. A 2-year-old presents to the emergency center with several days of rectal bleeding. The mother first noticed reddish-colored stools 2 days prior to arrival and has since changed several diapers with just blood. The child is afebrile, alert, and playful, and is eating well without emesis. He is slightly tachycardic, and his abdominal examination is normal. Which of the following is the best diagnostic study to order to confirm the diagnosis?

541. A 4-year-old boy is brought to the office because his school teacher thinks that his dusky blue appearance may have something to do with his inability to participate in regular school activities. His mother says that he has always appeared slightly out of breath. He has no history of any trauma, past surgery or medical conditions. His birth history is unremarkable. Physical examination reveals perioral cyanosis and a systolic murmur along the left sternal border. When the child squats, the murmur disappears and the cyanosis slightly improves. What is the most likely diagnosis of this patient?

542. 25. The 1-year-old brother of a child with known abetalipoproteinemia is evaluated by a pediatrician for the disease. The 1 -year-old has been exhibiting steatorrhea and ataxia. Which of the following would most strongly support the suspected diagnosis?

543. A 2-month-old infant is evaluated by a pediatric cardiologist. The infant was noted at birth to have an upper left sternal border ejection murmur. The infant at that time was not cyanotic, but slowly developed cyanosis over the next two months. At the time of the pediatric cardiologist's examination, an ECG showed right axis deviation and right ventricular hypertrophy. A chest x-ray film showed a small heart with a concave main pulmonary artery segment and diminished pulmonary blood flow. Which of the following is the most likely diagnosis?

544. A 6-year-old boy is brought to the emergency department because of the acute onset of headache, nausea, and vomiting. On arrival, physical examination reveals marked nuchal rigidity and funduscopic evidence of papilledema. A head CT scan reveals a solid tumor in the posterior fossa, centered in the cerebellar vermis and extending to the fourth ventricle. An emergency craniotomy is performed, during which a small sample of the tumor is sent to the pathologist for a frozen section consultation. Which of the following is the most likely diagnosis?

545. A 15-month-old girl is brought to the office by her mother due to failure to thrive. For the past three months, the child has had foul-smelling, non-bloody, loose stools 7 to 8 times daily. On examination, she is irritable and has a protruding belly and trace pre-tibial edema. There are erythematous vesicles symmetrically distributed over the extensor surfaces of her elbows and knees. Preliminary laboratory investigations are significant for hypochromic microcytic anemia, and stool examination is negative for ova or parasites. What is the most likely cause of failure to thrive in this child?

546. The 4-year-old child pictured below is noted to have the tooth decay as shown. This characteristic pattern of tooth decay is caused by which of the following?

547. A 5-month-old infant is brought to the office for the evaluation of persistent vomiting, failure to thrive, and developmental delay. His antenatal and postnatal histories are not known to his Caucasian foster parents, who adopted him when he was 4 months old. The physical examination reveals an infant with blonde hair, fair skin and blue eyes. His urine has a peculiar musty odor. His plasma phenylalanine level is 40 mg/dl and tyrosine level is normal. His urinary phenylpyruvic and a-hydroxy phenylacetic acid levels are both increased. What is the most likely etiology of this child's symptoms?

548. A 2 1/2-year-old child is evaluated by a neurologist because of difficulty walking. Neurological examination documents ataxia and mental retardation. The neurologist notes the presence of multiple telangiectasias involving the conjunctiva, ears, and antecubital fossae. The child also has a history of multiple respiratory tract infections. Immunoglobulin studies on the child would most likely demonstrate an absence of which of the following?

549. A 15-year-old boy with Duchenne muscular dystrophy is brought to the emergency department with increasing respiratory distress and cyanosis. On examination, he is diaphoretic, with gasping respirations, poor air entry, and diminished responsiveness. He is tachycardic at 160 beats/min. His chest x-ray film shows a lingular pneumonia, and he is intubated. He improves over the next 10 days with antibiotics but is not extubated secondary to hypoventilation on weaning because of muscle weakness. Which of the following modalities will most likely help wean him off the ventilator?

550. A 2-year-old child presents to the office with a paternal complaint of “bowlegs.” The girl has always had bowlegs; her previous pediatrician told the family she would grow out of it. Now, however, it seems to be worsening. Her weight is greater than 95% for age, and she has significant bowing out of her legs and internal tibial torsion; otherwise, her examination is normal. A radiograph of her lower leg is shown. Which of the following is the most likely diagnosis?

551. A 14-year-old high school student arrives to your clinic for well-child care. In reviewing his records you determine that his most recent immunization for tetanus was at 4 years of age. Which of the following should you recommend?

552. A 20-month-old male is brought to ER with high fever, confusion and a skin rash suggestive of measles. He has a history of recurrent respiratory infections over the last 6 months. The patient's family has recently emigrated from a rural Russian province. Which of the following forms of vitamin supplementation should be considered in this patient?

553. A 3-year-old male is brought to the emergency department for evaluation of right neck swelling. His parents noticed a lump on his right neck yesterday, which has since increased in size and is now erythematous and tender. He has been previously healthy except for mild upper respiratory tract symptoms last week. His temperature is 38.0 0C (100.4 0F), pulse is 90/min, and respiratory rate is 25/min. On examination, he is nontoxic appearing. A 5-cm anterior cervical lymph node is palpated on the right side. It is poorly mobile, warm, erythematous, and tender to palpation. There is no fluctuance or induration. What is the most likely organism causing these symptoms?

554. A 5-year-old boy is brought into the ER immediately after an unfortunate altercation with a neighbor’s immunized Chihuahua that occurred while the child was attempting to dress the dog as a superhero. The fully immunized child has a small, irregular, superficial laceration on his right forearm that has stopped bleeding. His neuromuscular examination is completely normal, and his perfusion is intact. Management should include which of the following?

555. Aunt Mary is helping her family move to a new apartment. During the confusion, 3-year-old Jimmy is noted to become lethargic. The contents of Aunt Mary’s purse are strewn about on the floor. In the ER, the lethargic Jimmy is found to have miosis, bradycardia, and hypotension. He develops apnea, respiratory depression, and has to be intubated. His condition would most likely benefit from which of the following therapies?

556. As a city public health officer, you have been charged with the task of screening high-risk children for lead poisoning. Which of the following is the best screen for this purpose?

557. An infant is born at terrn to a 27-year-old Caucasian female. The prenatal course was uncomplicated. The amniotic fluid is clear. Immediately after the delivery, the infant starts crying and is moving all four extremities actively. Heart rate is 140/rnin. He is making a grimace on the attempt to put the suction catheter into his nostrils. His body is pink, but extremities are cyanotic. Which of the following is the next best step in the management of the infant?

558. A 25-year-old woman brings her 5-day-old infant to the emergency room after noticing that he bruises very easily. Her pregnancy was normal, and the baby was born at term via vaginal delivery at home. This is the child's first visit to the doctor. He is exclusively breast-fed, and there is no family history of bleeding disorders. On physical examination, his vital signs are within normal limits. You note several ecchymotic skin lesions, but his exam is otherwise normal. Laboratory studies show the following: Prothrombin time 20 sec Partial thromboplastin time 37 sec Platelets 200,000/mm3 Which of the following is the most likely cause of his current condition?

559. A 7-year-old girl is brought to the physician because of an exanthematous rash associated with malaise and headache for 2 days. On examination, the child shows a fiery red facial rash with a characteristic "slapped cheek" pattern and pallor around the mouth. There is no fever. In immunocompromised patients, the pathogen that causes this condition may result in which of the following manifestations?

560. In the 2nd week of life, a previously healthy newborn develops diarrhea. The stools are watery and voluminous and continue even when the infant is fasting. Which of the following is the most likely pathogen?

561. A 17-year-old girl presents to the office with a 5-day history of a malodorous vaginal discharge. She is sexually active and uses condoms for sexual intercourse. On examination, a thin, white discharge is seen. A "fishy" odor is produced when KOH is added to the discharge. The vaginal fluid has a pH of 5. Which of the following is the most likely finding on a microscopic examination of the vaginal fluid?

562. A 9-month-old child comes in for a routine visit. She has had several episodes of otitis media in the past, but no major illnesses or hospitalizations. Her mother is concerned because the child was previously happy and social around other people, but now cries if her mother is not in the room. The child constantly wants to be held by her mother and becomes upset if her mother walks into the next room. Her grandmother keeps her during the day, and she now cries when her mother leaves her in the morning. Developmentally, she is crawling and waves bye-bye. She does not yet respond to her name or say words. She previously babbled but stopped several months ago. When you hide a toy with your hand, she lifts your hand to look for the toy. Which of the following is the best next step in the management of this child?

563. A 14-year-old boy is seen in the ER because of a 3-week history of fever between 38.3C and 38.9C (101F and 102F), lethargy, and a 2.7-kg (6-lb) weight loss. Physical examination reveals marked cervical and inguinal adenopathy, enlarged tonsils with exudate, small hemorrhages on the soft palate, a WBC differential that has 50% lymphocytes (10% atypical), and a palpable spleen 2 cm below the left costal margin. Which of the following therapies should be initiated?

564. A 2-year-old child is seen in the emergency center with a 10-day complaint of fever and a limp. The child has an elevated erythrocyte sedimentation rate (ESR) and the radiograph shown below. Which of the following statements about this child’s condition is correct?

565. A 12-year-old boy with cystic fibrosis presents to the emergency department with a 3-day history of severe coughing, which is productive of a yellow-greenish purulent sputum. He had fever and chills at home. He also complains of chest congestion and chest pain that is worse with coughing. On physical examination, his temperature is 39.6 C (103.2 F), blood pressure is 98/68 mm Hg, pulse is 102/min, and respirations are 24/min. He is noted to be lethargic. He has rales on the left lower lung field on auscultation, and chest radiography shows an infiltrate in the left lower lobe. Which of the following is the most appropriate initial antimicrobial therapy for this patient?

566. A 12-year-old boy is brought to the physician because of pain in his right leg for the past 3 weeks. The pain frequently occurs at night and is localized to the tibia, a few centimeters below the knee. The mother reports that the pain is promptly relieved by aspirin and that the child has had no fever. Examination reveals no tissue swelling or redness about the site of pain. X-ray films show a 1-cm radiolucent focus in the tibial cortex surrounded by marked bone sclerosis. Which of the following is the most likely diagnosis?

567. A 16-year-old African American male with sickle cell anemia presents complaining of a 1-week history of exertional dyspnea, fatigue, and generalized weakness. He denies fevers, chills, night sweats, or cough. His only medication is oxycodone for chronic pain. On physical examination, he weighs 68 kg (150 lbs) and is 168cm (66 in) tall His temperature is 36.7 0C (98 0F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 18/min. All organ systems appear normal Laboratory studies show: Hematocrit 20% Mean corpuscular volume 110 fl Reticulocyte count 1.0% Which of the following is the most likely mechanism underlying these findings?

568. A 15-year-old female with a history of bipolar disorder and psychosis presents to her physician's office requesting a pregnancy test. Her last menstrual period was 2 months ago. She states that her menses usually occur every 30 days. She is sexually active with one partner and occasionally uses condoms. She is concerned because she has gained 10 pounds in the last two months, and also complains of breast tenderness and milky white discharge from both nipples. She denies headaches, nausea, vomiting, diarrhea, or fever. Her vital signs are normal. Physical examination is unremarkable. A urine pregnancy test is negative. Which of the following is most likely responsible for this patient's symptoms?

569. A 7-year-old boy is brought to the physician because of recurrent headaches. The child feels nauseated before and during each attack, and derives some relief from lying down in a dark room. Noises, bright light, and fatigue seem to trigger the episodes. The child frequently complains of headaches at school, and his mother has been occasionally compelled to take him home. The mother is worried about the possibility of a serious illness. She reports that the child's father has similar headaches. The child's growth is normal, and a neurologic examination fails to reveal any abnormality. Which of the following is the most likely diagnosis?

570. A 17 -year-old boy is brought to the emergency department by his father after the boy began threatening him at home. Over the last several months, the father reports, the boy has been increasingly abusive. He was recently involved in a fist fight at school. The boy states that there is nothing wrong. He is otherwise healthy. He denies alcohol use, but does admit to occasional marijuana use. On examination he has acne on his forehead and back and his hairline is receding. There is palpable tissue underneath his nipples bilaterally Heart and lung exams are normal. What substance is this boy most likely abusing?

571. A 9-month-old infant is brought to the emergency department with lethargy and tachypnea. He was healthy before developing fever and diarrhea four days ago. He has been taking some formula, but has had two to three episodes of diarrhea with each bottle. He has lost three pounds (1 .4 kg) since his routine check-up two weeks ago. He has had one wet diaper in the past twenty four hours. On examination, his temperature is 102.5F (39.1c), pulse is 200/min, respiratory rate is 42/min, and blood pressure is 70/45 mm Hg. He is lethargic with decreased tone and decreased deep tendon reflexes. His mucous membranes are dry. Cardiopulmonary exam reveals tachycardia and tachypnea. His abdominal exam is unremarkable. Capillary refill is four seconds. Laboratory results are shown below. Chemistry panel Serum sodium 165 mEq/L Serum potassium 4.5 mEq/L Chloride 108 mEq/L Bicarbonate 14 mEq/L Blood urea nitrogen (BUN) 20 mg/dl Serum creatinine 0.8 mg/dl Calcium 10.0 mg/dl Blood glucose 98 mg/dl Which of the following fluids should be used as a bolus in the resuscitation of this infant?

572. A 15-year-old otherwise healthy boy presents with a complaint of intermittent abdominal distention, crampy abdominal pain, and excessive flatulence. He first started noticing these symptoms when he moved into his father’s house, and his stepmother insisted on milk at dinner every night. He has normal growth, has not lost weight, and has no travel history. Which of the following is the most appropriate study to diagnose his condition?

573. A 6-week-old infant is admitted to the hospital with jaundice. Her outpatient blood work demonstrated a total bilirubin of 12 mg/dL with a direct portion of 3.5 mg/dL. Which of the following disorders is most likely to be responsible?

574. A 12-year boy is brought to the emergency room by his parents after a several day history of progressive weakness. He has been a healthy child who has met all development milestones and all his immunizations are up to date. He reports that he had an upper respiratory infection 2 weeks ago. On physical examination, his vital signs are labile with a pulse range of 60-100/ min and systolic blood pressure ranging from 80-120 mm Hg. He is alert and oriented. Neurologic examination is impressive for bilateral weakness in the upper and lower extremities. Deep tendon reflexes are absent and sensation is intact. Which of the following is the most likely diagnosis?

575. A 15-year-old boy with tall stature presents with decreased exercise tolerance over the past 2 months. He states that he used to play two games of basketball with no problem, but he now can play only one game. On physical examination, his weight is at the 25th percentile, and his height higher than the 95th percentile. He is thin and has a gangly body habitus. His fingers are long and thin. There is pectus deformity in his chest. His joints are hyperextensible. An ophthalmologic examination reveals mild subluxation of the lens. Which of the following is the most likely finding on an echocardiogram?

576. A 2-year-old arrives in the emergency center after having swallowed a button battery from one of her toys. She is breathing comfortably, without stridor. Radiographs show the battery to be lodged in the esophagus. Which of the following is the correct next step?

577. A 2-year-old boy is brought to the office due to recurrent skin and soft tissue infections. When he was 2- months-old, he had a perianal furuncle that was incised and drained because it was unresponsive to oral antibiotics. At 7 months of age, he had a left inguinal Klebsiella pneumoniae lymphadenitis. His other past infections include a left calf cellulitis that grew Serratia marcescens and a left inguinal abscess that grew Staphylococcus epidermidis. On examination, he has hepatosplenomegaly, and enlarged axillary and inguinal lymph nodes. The screening tests for humoral, cell-mediated, and complement-mediated immunity are normal. The nitroblue tetra zolium (NBT) slide test is abnormal. What is the most likely diagnosis?

578. A previously healthy 2-year-old male is brought to the emergency department after experiencing a seizure-like episode. His parents report that he has been healthy with the exception of mild upper respiratory symptoms for the past 24 hours. During the episode, his parents state that he fell down and had rhythmic, jerking movements of his arms and legs. The episode lasted about three minutes. The patient was sleepy when the emergency personnel arrived. Vital signs are temperature 39 .2 c (102 .5 F), pulse 120/min, and respiratory rate 25/min. The patient is alert and oriented in the emergency department. On examination, there is mild rhinorrhea and the left tympanic membrane is erythematous, bulging, and poorly mobile. The neck is supple. A complete neurological exam is unremarkable. After treating this patient's fever, which of the following is the next best step in the management of this patient?

579. An awake, alert infant with a 2-day history of diarrhea presents with a depressed fontanelle, tachycardia, sunken eyes, and the loss of skin elasticity. Which of the following is the correct percentage of dehydration?

580. A newborn infant is brought to the nursery for evaluation after delivery. The mother reports that the pregnancy was uncomplicated, but she had only two prenatal visits. The infant was born via normal spontaneous vaginal delivery and required no resuscitation. The infant has hepatosplenomegaly on examination. While in the hospital, the infant requires treatment for anemia and hyperbilirubinemia. On subsequent examinations, the infant has clear rhinorrhea and ulcerative lesions on his feet. Which of the following congenital infections is most likely in this patient?

581. A 2 week post mature baby is born and immediately exhibits severe respiratory distress. Previously, green-tinged meconium was noted in the amniotic fluid. Which of the following is the most appropriate next step?

582. A fetus is delivered at 40 weeks' gestation. During labor, the fetal heart monitor shows late decelerations and loss of short- and long-term variability. The membranes are ruptured to expedite the delivery. The fluid is noted to contain meconium. The infant is delivered 45 minutes later. At delivery, the infant appears to be cyanotic and limp. He has poor tone and deep reflexes. Moro's reflex is absent. Ten hours later, he experiences a seizure. Which of the following best explains this infant's perinatal course?

583. An 18-month-old infant is found with the contents of a bottle of drain cleaner in his mouth. Which of the following treatment options is most appropriate?

584. A 16-year-old male, despondent over a recent breakup, tries to commit suicide by taking an unknown quantity of an unknown material he found at home. He is brought to the emergency center by his parents within 30 minutes of the ingestion. For which of the following household materials and medications should he be given activated charcoal as part of his emergency center treatment?

585. A 3-year-old African American boy is brought to the emergency department with sudden onset of difficulty walking. His mother reports that his right hand also seems "clumsy." The boy's past medical history is significant for a hospitalization one year ago for severe upper extremity pain and hand swelling. On physical examination, he has a blood pressure of 90/60 mmHg, heart rate of 120/min, temperature of 36.7°C (98°F), and respiratory rate of 22/min. Which of the following would be most helpful in diagnosing his condition?

586. A 25-year-old woman comes to your office for counseling. She says that her husband has cystic fibrosis, and that she has no family history of this disease. They are planning to have a child. She wonders what the probability is for their baby to have cystic fibrosis. Which of the following is your best response in this situation?

587. A 7-year-old boy is brought to the physician because of persistent nasal obstruction for 6 months. There is no: personal or family history of allergic disorders, Examination of the nasal fossae reveals bilateral ethmoidal polyps that protrude into the middle meatus and nasal cavity. Which of the following is the most appropriate next step in diagnosis?

588. A neonate is very small for gestational age, shows hypotonia, marked skeletal muscle, and subcutaneous fat hypoplasia. During delivery, a large volume of amniotic fluid was released at rupture of membranes. The placenta was small, and only a single umbilical artery was noted. The face has a pinched appearance with hypoplastic orbital ridges, short palpebral fissures, and a small mouth and jaw. The head is small with prominence of the occiput. The ears are low set and malformed. The infant's fists are clenched, with overlapping of the third and fourth fingers. The feet are clubbed, and the great toe is shortened. Which of the following is most likely diagnosis?

589. The delivery of a newborn boy is remarkable for oligohydramnios. The infant (pictured) is also noted to have undescended testes and clubfeet, and to be in respiratory distress. Which of the following is the most likely diagnosis to explain these findings?

590. A 17-year-old boy is brought to the emergency department by his parents with the complaint of coughing up blood. He is stabilized, and his hemoglobin and hematocrit levels are 11 mg/dL and 33%, respectively. During his hospitalization, he is noted to have systolic blood pressure persistently greater than 130 mm Hg and diastolic blood pressure greater than 90 mm Hg. His urinalysis is remarkable for hematuria and proteinuria. You are suspicious the patient has which of the following?

591. A 10-year-old presents with 2months history of heavy menstrual-like bleeding. Menarche occurred 6 months ago and this first menses consisted of spotting for 3-4 days without cramps. Subsequent periods were light in flow but lasted 6 to 8 days. Which of the following is the most likely cause of her bleeding?

592. A 4-year-old boy presents with 5-day history of fever and increased irritability. His temperature is 40. 2 C (104. 3 F), blood pressure is 98/68 mm Hg, pulse is 112/min, and respirations are 24/min. On physical examination, he is noted to have bilateral cervical lymphadenopathy, cracked lips, strawberry tongue, and bilateral conjunctival injection. His palms and soles are erythematous. There is a polymorphous macular rash generalized on his body. Which of the following is the most appropriate pharmacotherapy?

593. A 13-year-old male is brought to the physician for evaluation of intermittent left knee pain that arose three months ago. He does not remember any trauma to his knee. The pain worsens after basketball games, but improves some with rest. He has been taking non-steroidal anti-inflammatory medications with some relief. On physical examination, he has edema and tenderness over the proximal tibia at the site of the patellar tendon insertion. Examination of the knee joint is normal and no effusion is present. His knee pain is reproducible by extending the knee against resistance. A lateral radiograph of his knee is shown below. Which of the following is the most likely cause of this patient's knee pain?

594. A 4-day-old infant is brought to the physician for an outpatient follow-up visit. The mother's pregnancy and delivery were uncomplicated. The infant weighed 3.4kg (7 .5 lb) and was 19 in (48.2 cm) long at birth. He did well in the newborn nursery and was discharged from the hospital on day 2 of life. Today his mother reports that he is exclusively breastfed, and nurses for 10 minutes every 3 hours. He has 3-4 wet diapers a day, and has not had a bowel movement for two days. On examination, he weighs 2.95 kg (6.5 lb) and is 19 in (48.2 cm) long. He appears jaundiced on the face and chest. The remainder of the physical examination is unremarkable. Laboratory values are shown below. Total bilirubin 15 mg/dl Direct bilirubin 1 mg/dl Infant's blood type O positive Mother's blood type A positive Which of the following is the most likely cause of this infant's hyperbilirubinemia?

595. A 16-year-old boy with a history of ulcerative colitis presents to the physician complaining of diarrhea and a rash. He states that his appetite has been decreased recently, and also complains of nausea and abdominal pain in addition to watery diarrhea. He has an erythematous rash on his distal arms and legs that "burns". His mother reports that he has had poor concentration and has been irritable lately. Vital signs are stable. Examination reveals a beefy red tongue that appears swollen. Abdominal examination is normal. The rash resembles a sunburn and is located on his distal arms and legs. It is symmetrical and tender to palpation. Neurological examination is normal. This patient's symptoms are most likely due to a deficiency of which of the following vitamins?

596. You are called by a general practitioner to consult on a patient admit- ted to the hospital 4 days ago. The patient is a 7-month-old white boy with poor weight gain for the past 3 months, who has not gained weight in the hospital despite seemingly adequate nutrition. You take a detailed diet his- tory from his foster mother, and the amounts of formula and baby food intake seem appropriate for age. Physical examination reveals an active, alert infant with a strong suck reflex who appears wasted. You note generalized lymphadenopathy with hepatomegaly. In addition, you find a severe case of oral candidiasis that apparently has been resistant to treatment. Which of the following is the most appropriate next step in the evaluation or treatment of this child?

597. A 5-year-old boy presents with the severe rash shown in the photographs. The rash is pruritic, and it is especially intense in the flexural areas. The mother reports that the symptoms began in infancy (when it also involved the face) and that her 6-month-old child has similar symptoms. Which of the following is the most appropriate treatment of this condition?

598. A 13-year-old girl returns to her physician for followup of a strep throat, for which she had been treated 3 weeks previously. After performing a throat culture, the physician asks how school is going. There is dead silence. Her mother says that her daughter has missed the last 4 weeks of school. Which of the following is the most appropriate initial step in management?

599. A 1 -year old child is brought in for a well baby check-up. His parents report that he has been of good health and began walking a few weeks earlier. They are concerned that he tends to bump into things and falls more than his older sister did. Family history is significant for retinoblastoma. On examination, the pediatrician notes leukocoria of the left eye. No significant lymphadenopathy is present, and there is no enlargement of the liver or spleen. The child's height and weight are normal for age. Which of the following is the most appropriate next step in management?

600. A 4-year-old boy is being evaluated for short stature. He has a history of multiple bone fractures in the past. He requires a wheelchair to ambulate and has hearing difficulty. On physical examination, his height is below the 5th percentile. His sclerae are blue in color. There is marked deformity of his lower extremities. Which of the following is the most likely diagnosis?

601. A 6-month-old infant presents to the emergency department with the new onset of weak cry, decreased activity, and poor feeding. The mother also states that the infant has been constipated for the past 2 days. On physical examination, the infant has a very weak cry, poor muscle tone, and absent deep tendon reflexes. Which of the following is the most likely diagnosis?

602. You are called to examine a 2-day-old male, newborn after he was noted to be cyanotic. He was born at term. His antenatal and birth histories are unremarkable. Auscultation reveals a holosystolic murmur at the left, lower sternal border and a single S2. No rales or rhonchi are heard. Chest radiograph reveals decreased pulmonary vascular markings and a normal-sized heart. EKG reveals left axis deviation. What is the most likely diagnosis?

603. A 6-year-old Asian boy is brought by his parents to the office due to high-grade fever and rash for the last 9 days. A brick-red, maculopapular rash first appeared on his face and subsequently spread to his trunk and extremities. Prior to the outbreak of the rash, he had a non-productive cough, tearing of eyes, runny nose, sneezing, and intermittent nasal obstruction. Laboratory findings are as follows: Hct 46% WBC 2,000/mm3 Platelets 160,000/mm3 Which of the following has been shown to reduce the morbidity and mortality rates of patients with this kind of infection?

604. A 2-year-old boy has been vomiting intermittently for 3 weeks and has been irritable, listless, and anorectic. His use of language has regressed to speaking single words. In your evaluation of this patient, which of the following is the most reasonable diagnosis to consider?

605. A 15-year-old boy is seen in the pediatrician's office for a health maintenance physical examination. The boy reports a heavy, dragging sensation in his left scrotum. The sensation is more pronounced after exercise. He denies any scrotal pain. He is not sexually active. Examination of his genitalia indicates Tanner stage 4. There is a palpable fullness over his left scrotum. Both testes are normal in size and smooth in contour. Which of the following is the most likely explanation of these findings?

606. A 5-year-old child undergoes a school entrance physical examination. The pediatrician notices grey-brown pigmentation on the skin of his forehead, hands, and pretibial regions. Subconjunctival areas near the corneoscleral junction show wedge-shaped, yellow-brown discoloration (pingueculae). Enlargement of both the spleen and the liver are noted on abdominal examination. Needle biopsy of the spleen demonstrates the presence of unusually large (20- to 100-mm diameter) reticuloendothelial histiocytes with a "crumpled-silk" appearance. Bone marrow biopsy demonstrates the presence of the same type of cells. Which of the following is the most likely diagnosis?

607. A term male infant is found to be cyanotic shortly after birth and requires endotracheal intubation. On physical examination, his blood pressure is 68/34 mm Hg (equal in all four extremities), pulse is 180/min, and respirations are 32/min. His precordium is dynamic, has a grade III systolic murmur, and a single S2. Chest radiography shows a normal heart size and increased pulmonary vascular markings. An arterial blood gas on an FiO2 of 100% shows pH 7.34; PaCO2, 47 mm Hg; PaO2, 46 mm Hg. Which of the following diagnoses is most consistent with these findings?

608. A 6-month-old boy is found to have bilateral metaphyseal fractures of both proximal and distal ends of the tibia. The mother says that her boyfriend takes care of the infant while she is at work. Her boyfriend explains the injuries as the result of multiple falls from bed. Which of the following is the most likely diagnosis?

609. A 15-year-old African-American girl has a facial rash and vague joint pains. Her temperature is 37.2C (99F). On examination, a malar erythematous rash is noted. Her laboratory evaluation is significant for anemia, leukopenia, and a normal platelet count. Her antinuclear antibody and Rapid Plasma Reagin (RPR) tests are positive. Which of the following tests is confirmatory for this patient's condition?

610. A 7 -year-old boy is rushed to the emergency department after falling on his outstretched hand. He immediately complained of right arm pain after the accident, and he currently cannot move his arm due to the pain. He is crying and holding his right arm in flexion. There is ecchymosis just above his elbow. He cries out in pain when his arm is moved. An x-ray reveals a supracondylar fracture. What secondary injury is most commonly associated with this patient's fracture?

611. A patient with hair loss is shown below. The lesion does not fluoresce with a Wood lamp and has not responded well to a variety of topical agents. The lesion is boggy, is spreading, and has tiny pinpoint black dots throughout. Which of the following is the most likely diagnosis?

612. An 8-year-old sickle-cell patient arrives at the emergency room (ER) in respiratory distress. Over the previous several days, the child has become progressively tired and pale. The child’s hemoglobin concentration in the ER is 3.1 mg/dL. Which of the following viruses commonly causes such a clinical picture?

613. A 2-year-old child has had red, weeping, crusted lesions of the face, scalp, diaper area, and extremities since about age 2 months, with multiple periods of exacerbation and improvement. Attempts to remove potentially irritating substances have not modified the course of the rashes. The child is noted to be constantly scratching and rubbing involved areas. There is a strong family history of hay fever and asthma. Which of the following is the most likely diagnosis?

614. A 5-year-old boy is brought to clinic with increasing right lower foot pain. He stepped on a nail several days ago. At that time, the family had sought medical attention. The child was given a tetanus shot, and the wound was extensively irrigated. On examination, the foot is tender, swollen, warm, and erythematous. Osteomyelitis is suspected. Which of the following is the most appropriate next step in diagnosis?

615. A 16-year-old girl with an incomplete vaccination record received one dose of the measles, mumps, and rubella (MMR) vaccine during a doctor's visit. One month later, she learns that she is 9 weeks pregnant, and she is concerned about potential birth defects resulting from the MMR vaccine. Which of the following most closely approximates the risk of birth defects secondary to MMR vaccine exposure during the first trimester?

616. A 6-week-old male infant who was born at 32 weeks' gestation with a birth weight of 1500 g, has had an average weight gain of 8 g/day since birth. He takes an iron-fortified formula that is 24 kcal/oz. His calorie intake is about 125 kcal/day. It is noted that his stool is poorly formed and bulky. Which of the following dietary modifications will most likely result in decreased steatorrhea and improved weight gain?

617. A previously healthy 4-year-old girl is brought to the office due to a 12-day history of persistent, thick, nasal discharge, nasal congestion, headache, cough, and intermittent low-grade fever. The cough is worse at night, but there is no wheezing. Her temperature is 37.2C (99F), pulse is 90/min, and respirations are 15/min. Examination shows an alert, interactive child breathing comfortably. She has clear tympanic membranes, congested posterior nasal pharynx with thick and purulent mucus, and red, swollen nasal turbinates. Her maxillary sinuses are mildly tender. Her lungs are clear on auscultation. What is the most appropriate next step in the management of this patient?

618. A 7-year-old Caucasian boy is brought to the clinic because of poor performance in school. His mother says that his teachers have been complaining about his poor attention in the classroom for the past 8 months. They have also complained that he is out of his seat often, fidgets, and talks excessively, gets distracted easily, and interrupts class and other students. His mother has noticed that he often loses his things, and she is having more and more difficulty disciplining him at home. His antenatal and postnatal history is insignificant. His parents never had any similar problems with his 10-year-old sister. What is your clinical diagnosis?

619. A 13-year-old comes to your office expressing concern about his height. He had first seen you a year prior for his routine checkup and a preparticipation sports physical for soccer (see growth curve). Now in the eighth grade, al of his friends are taller than he is, and he is at a disadvantage on the soccer field playing against much larger boys. After obtaining height information from his parents shown here, you order a skeletal bone age radiograph. Which of the following results would allow you to assure him of an excellent prognosis for normal adult height?

620. The parents of the child pictured below bring him to the office for evaluation of short stature. At 5 years of age, he is the shortest child in his kindergarten class. His development is normal, and he is reading on a first grade level. Both parents are of normal height, and this child resembles no one in the family. Which of the following is the most likely diagnosis?

621. A 3-day-old, full-term baby boy is brought into the emergency department because of feeding intolerance and bilious vomiting. X-rays films show multiple dilated loops of small bowel and a "ground glass" appearance in the lower abdomen. The mother has cystic fibrosis. Which of the following diagnostic tests would also have therapeutic value?

622. A 17-year-old girl presents with a 4-week history of intermittent fever, increasing fatigue, generalized myalgia, and swelling of both her knees and ankles. There is a fine erythematous rash on her back, and she has swollen knees and ankles; the remainder of her physical examination is unremarkable. Initial laboratory evaluation shows: Leukocytes 11,400 cells/mm3 Hemoglobin 8.8 g/dL Blood urea nitrogen 4 mg/dL Creatinine 1.4 mg/dL Glucose 98 mg/dL C3 complement 36 mg/dL (normal >80 mg/dL) Antinuclear antibody titer 1:3200 Anti-double-stranded DNA titer 1:640 Antineutrophil cytoplasmic antibodies: Negative Urinalysis Moderate hematuria (50 RBC/hpf), Moderate proteinuria (400 mg/dL) Which of the following is the most likely diagnosis?

623. A vomiting infant is brought to the emergency room. The blood work results reveal a normal blood count, but a hyponatremic, hypochloremic, metabolic alkalosis. Which of the following would be consistent with these findings?

624. A 5-year-old boy develops a headache, cough, myalgia and a fever. He has been a healthy child with all immunizations up to date. He is given a decongestant and an aspirin for his symptoms with some relief. However, 4 days later, he is brought back by his parents because of persistent vomiting and irritability. On physical examination, he is found to be semicomatose, becoming combative on stimulation. Which of the following levels should be measured to aid in the diagnosis of this patient?

625. A 3-year-old boy is admitted for seizure-like activity. He has been a healthy child and has been meeting all development milestones. His immunization schedule is upto-date. Examination is notable for an erythematous throat and fever. His convulsions require IV administration of a benzodiazepine. Serum analysis reveals a normal white cell count with mild basophilic stippling. The lumbar puncture reveals elevated CSF pressure. Head CT scan is notable for cerebral edema. Which of the following is the next diagnostic step?

626. A 2-week postmature neonate exhibits severe respiratory distress immediately after birth. Previously, greentinged meconium was noted in the amniotic fluid. Which of the following is the most appropriate next step in management?

627. A 12-year-old girl has a solitary thyroid nodule found on routine examination; she has no symptoms. Which of the following is the most appropriate next step for this patient?

628. The 16-month-old male infant pictured below was recently brought from a developing country to the United States. The family history reveals that his father had an eye and a leg removed. Which of the following is the most likely diagnosis?

629. A 12-year-old African American boy is brought to the office due to a 2-day history of high-grade fever and chills. He was apparently well before the onset of fever. He has no bone pain. He has sickle cell disease and has had 4 hospitalizations for painful crises and one episode of osteomyelitis. His blood pressure is 90/60 mm Hg, pulse is 100/min, respirations are 22/min and temperature is 38.9 C (102F). He appears drowsy. His laboratory report shows a total WBC count of 16,000/mm3 with 12% bands and Hb of 9.0 g/dl. Which of the following is the most likely cause of this patient's condition?

630. A 12-year-old male is brought to your office by his mother because of a several month history of back pain. He also experienced bed wetting recently. His past medical history is insignificant. He tried acetaminophen for pain relief. He does not smoke or consume alcohol. His temperature is 36.7 C (98 F), blood pressure is 110/65 mmHg, pulse is 80/min, and respirations are 16/min. Physical examination reveals a palpable "stepoff" at the lumbosacral area. Straight-leg raising test is negative on both sides. Perianal sensation tested by pinprick test is decreased, but anal reflex is normal. What is the most probable diagnosis in this patient?

631. A 16-month-old is taken to the emergency room after falling while learning to walk. The toddler has an enlarging, swollen bruise on his forehead, which is now over two inches across. The parents say that the bruise is noticeably larger than it was when they entered the emergency room an hour earlier. A blood sample is drawn, and the child oozes blood at the puncture site for 25 minutes. Clotting studies on the blood sample show a prolonged PTT and a normal PT. Follow-up studies show very low levels of factor VIII. Which of the following is the most likely diagnosis?

632. A 7-day-old boy who is the product of an uncomplicated gestation is brought to the physician because of hypospadias. The baby is otherwise healthy, and is urinating without any difficulty. On physical examination, vital signs are stable, lungs are clear and the heart is beating at a regular rate. The only abnormal physical finding is the hypospadias. Urinalysis is negative for infection. Which of the following is the most appropriate next step?

633. A 15-year-old Caucasian boy is injured during a football game. He is taken to the emergency department for x-ray films of his leg to rule out a possible fracture. The radiologist reports that the boy has evidence of an aggressive bone tumor with both bone destruction and a soft tissue mass. Later, the pathologist reports that the bone biopsy reveals a bone cancer with some of the tumor tissue displaying neural differentiation. Which of the following is the most appropriate next step in management?

634. A 7-year-old boy has a history of repeated urinary tract infections that have been treated by the empiric use of antibiotics. The parents are not satisfied with the care the child is receiving, and they take him to a pediatric urologist. Evaluation by voiding cystourethrogram shows that the patient has vesicoureteral reflux without ureteral or upper tract dilatation (grade one reflux). Which of the following is the appropriate management for this child?

635. A 10-year-old boy was healthy until about 10 days ago when he developed 7 days of fever, chills, severe muscle pain, pharyngitis, headache, scleral injection, photophobia, and cervical adenopathy. After 7 days of symptoms he seemed to get better, but yesterday he developed fever, nausea, emesis, headache and mild nuchal rigidity. Cerebrospinal fluid (CSF) shows 200 white blood cells (WBC) per microliter (all monocytes) and an elevated protein. Correct statements about this infection include which of the following?

636. A previously healthy 8-year-old boy has a 3-week history of low-grade fever of unknown source, fatigue, weight loss, myalgia, and headaches. On repeated examinations during this time, he is found to have developed a heart murmur, petechiae, and mild splenomegaly. Which of the following is the most likely diagnosis?

637. A 10-year-old boy is brought by his parents to the emergency department for the evaluation of headaches, fever, chills, and a rash over his neck, chest, and axillae. The rash appeared today, and for the past two days the child was complaining of a sore throat. He has no history of allergies, and his immunizations are up-to-date. His blood pressure is 112/70 mmHg, pulse is 1 08/min, respirations are 20/min, and temperature is 38.3C (101 F). Examination reveals an erythematous rash with a sandpaper-like texture, and which blanches with pressure. There is submandibular tender lymphadenopathy, and the throat is erythematous with gray-white exudates. What is the most likely diagnosis?

638. A 2-year-old boy is referred to your office for the evaluation of a white eye reflex. His mother suspects a hearing problem because he does not respond when she calls out his name. The physical examination reveals a continuous, machinery murmur over the right 2nd intercostal space and purple lesions on his arms and chest. The initial investigations reveal thrombocytopenia. What is the most likely diagnosis?

639. A 10-year-old male fell while riding his scooter down a steep hill. In the Emergency Department, his injuries included a fractured wrist and a lacerated spleen, which required surgical removal. Two years later he is diagnosed with bacterial pneumonia. Which of the following bacterial agents is the most likely pathogen for this patient's pneumonia?

640. A 15-year-old girl presents with diplopia after prolonged reading and ptosis that worsens in the afternoon. On examination, she is noted to have bilateral ptosis, impaired extraocular muscle movements, facial weakness, and generalized hypotonia and weakness increasing with repetition. Which of the following is the best diagnostic test for this disorder?

641. A 12-year-old boy presents to his pediatrician with frequent episodes of headache, nausea, blurry vision, and sweating. On physical examination, his temperature is 37.4 C (99.3 F), blood pressure is 148/94 mm Hg, pulse is 92/min, and respirations are 18/min. The rest of his examination is unremarkable. His 24-hour urinary vanillylmandelic acid (VMA) and metanephrines are increased. An abdominal CT reveals an extrarenal mass above the left kidney. Which of the following is the most appropriate pharmacotherapy?

642. A 12-year-old girl with mild asthma comes to the office for a health maintenance visit. Her mother states that she is using her albuterol inhaler 2-3 times a week and that she has a cough that wakes her up at night about 3 times a month. On physical examination, she has diffuse inspiratory and expiratory wheezes. She has no accessory muscle use. Pulse oximetry shows 95% oxygen saturation on room air. Which of the following is the most appropriate treatment for her at this time?

643. You find a discrete, whitish polyp that extends through the tympanic membrane in a child with a history of recurrent otitis media. This most likely represents which of the following?

644. A 20-month-old child is brought to the ED because of fever and irritability and refusal to move his right lower extremity. Physical examination reveals a swollen and tender right knee that resists passive motion. Which of the following is the most likely to yield the diagnosis in this patient?

645. A 6-year-old boy is brought to the office by his mother for the evaluation of a "skin disease." The physical examination reveals multiple vesiculopustular lesions on his face and neck. Some lesions are colored golden-yellow and encrusted. The crust is thick and adherent to the underlying skin. The rest of his physical examination is within normal limit. What is the most appropriate treatment for his skin condition?

646. A 5-day-old male premature infant in the NICU develops a decreased level of consciousness, hypotonia and decreased spontaneous movements. He was delivered vaginally at 32 weeks of gestation, and his birth weight was 1800g. Examination reveals a lethargic infant with a weak and high-pitched cry, prominent scalp veins, tense fontanels, and eyes directed downward, poor suckling, hypotonia. CT scan reveals dilation of the entire ventricular system, with distinct enlargement of the subarachnoid space over the cerebral cortex. What is the most likely cause of the patient's condition?

647. A 12-month-old infant presents with bilious vomiting and abdominal distention for 10 hours. His mother states that the infant has been constipated since birth and failed to pass meconium during the first 48 hours of life. On examination, he is very irritable. His length and weight are both below the 5th percentile according to his age. His abdomen is moderately distended. After a digital rectal examination, a fair amount of stool ejects out from the anus. Which of the following is the most likely diagnosis?

648. A 9-year-old boy is brought to the pediatrician's office for bed-wetting. His mother states that he has never been dry at night. Occasionally, he has problems controlling his bladder during the day. On physical examination, his blood pressure is 98/56 mm Hg. Both his weight and height are below the 5th percentile for his age. His bladder is enlarged and palpable above the symphysis pubis. Which of the following is the most likely cause of his problem?

649. A 4-day-old female infant presents to the emergency department with vomiting and abdominal distention. The mother states that the vomitus was green. The infant also has had difficulty feeding and has been hard to console. The mother had an uncomplicated pregnancy. The infant passed meconium within 12 hours after birth. She also had several small, seedy, yellowish stools each day since birth. On physical examination, she is very irritable, her anterior fontanelle is slightly depressed. Her abdomen is distended. Which of the following is the most likely diagnosis?

650. An 8-year-old boy presents to the pediatrician's office with a headache for the past 3 weeks. His mother also states that he has been more tired and has had frequent nose bleeding for the past month. On physical examination, his height and weight are both below the 5th percentile for his age. His blood pressure is 152/86 mm Hg in all four extremities. His pulse is 74/min, and respirations are 16/min. His heart examination is normal with no murmur. His peripheral pulses are strong and symmetric. Urinalysis and serum electrolytes are ordered. Which of the following is the most appropriate next step in diagnosis?

651. A 1-year-old presents for a well-child checkup, but the parents are concerned about giving the child his immunizations. Which of the following is a true contraindication to the administration of the fourth DTaP (diphtheria and tetanus toxoid and acellular pertussis) vaccine?

652. An 11-year-old boy presents with fever and sore throat. A rapid-strep test confirms streptococcal pharyngitis. He is leaving for a summer camp in 2 days. In the past, he has had problem finishing the whole course of antibiotic treatment. Which of the following is the best treatment for his streptococcal pharyngitis?

653. A previously healthy 11-year old boy presents to the physician with a fever and persistent vomiting for 4-5 days. Initially, the emesis was clear, but now it contains streaks of bright red blood. Findings on a physical examination, complete blood count, and serum electrolytes are within normal limits. Which of the following is the most likely cause of the hematemesis?

654. A 7 -year-old boy is brought to the emergency department after falling on his outstretched hand. On examination, there is minimal swelling at the right elbow. The skin on the right forearm appears tense, and severe pain is present. The brachial pulses are good bilaterally, and sensations are intact in both upper limbs. X-rays of the right upper limb show a displaced anterior fat pad. Which of the following statements is true about this condition?

655. An 8-week-old female infant is brought to the office by her Caucasian mother for a well-baby examination. She was born at 34 weeks gestation, and weighed 2.9kg (6.51b) at birth. She has been exclusively breastfed since birth, and her growth and development are normal for her age. The physical examination is normal, except for mild pallor. At this time, what is the most appropriate nutritional intervention for this patient?

656. A 6-year-old boy is brought to the clinic due to persistent leg pain. Over the last few months, he has been constantly complaining of pain in his legs. The painful episodes occur only at night, and last a few hours each. His mother has been treating him with over-the-counter medications. He is able to walk and run to school without any complaints. He has no fever, chills and history of trauma. On examination, there is no obvious trauma to his legs, and the limb exam is completely normal. His parents are very worried and ask that you "do something.” Which of the following is the most appropriate next step in management?

657. Parents bring a 5-day-old infant to your office. The mother is O negative and was Coombs positive at delivery. The term child weighed 3055 g (6 lb, 1 oz) at birth and had measured baseline hemoglobin of 16 g/dL and a total serum bilirubin of 3 mg/dL. He passed a black tarlike stool within the first 24 hours of life. He was discharged at 30 hours of life with a stable axillary temperature of 36.5°C (97.7°F). Today the infant’s weight is 3000 g, his axillary temperature is 35°C (95°F), and he is jaundiced to the chest. Parents report frequent yellow, seedy stool. You redraw labs and find his hemoglobin is now 14 g/dL, and his total serum bilirubin is 13 mg/dL. The change in which of the following parameters is of most concern?

658. You are called to a delivery of a woman with no prenatal care; she is in active labor but has no history of amniotic rupture. The biophysical pro- file done in the emergency center revealed severe oligohydramnios. When you get this infant to the nursery, you should carefully evaluate him for which of the following?

659. A 3-month-old infant has a history of chronic constipation. A fulminant watery diarrhea develops over a period of 2 days, and the infant is taken to the emergency department in an obviously severely dehydrated state. Plain x-ray films of the abdomen demonstrate a massively dilated transverse colon. Which of the following is the most likely diagnosis?

660. A mother brings her 9-month-old daughter to the pediatrician with complaints of a rash. The mother states that the infant had a high fever [temperature up to 40.0 C (104 F)] for 3 days prior to developing the rash, but is now afebrile. The mother also says that the infant has had a runny nose and a slight cough for the past 3 days. On examination, there is a fine macular rash on the infant's trunk and neck. The examination is otherwise within normal limits, and the infant is playful and smiling. Which of the following is the most likely diagnosis?

661. A newborn infant becomes markedly jaundiced on the second day of life, and a faint petechial eruption, first noted at birth, is now a generalized purpuric rash. Hematologic studies for hemolytic diseases are negative. Acute management should include which of the following?

662. A 14-year-old girl, angry at her mother for taking away her MP3 player, takes an unknown quantity of a friend’s pills. Within the first hour she is sleepy, but in the emergency center she develops a widened QRS complex on her electrocardiogram (ECG), hypotension, and right bundle branch block. The therapy you would initiate for this ingestion is which of the following?

663. A 3-year-old boy of African descent is brought to your office by his stepfather because of easy bruising. He says that the child bruises easily even without trauma. The child started playing games by himself recently. He has a past history of clavicular fracture, which the stepfather attributes to a fall down a set of stairs. The history of the biological father is unknown. On examination, there is a right knee effusion with decreased range of motion, and multiple soft tissue hematomas on the thigh. What is the most appropriate diagnostic step in management?

664. An 8-year-old boy with sickle cell disease presents with left leg pain and a high fever. He has been refusing to walk since yesterday. On physical examination, his temperature is 39.8 C (103.6 F), blood pressure is 122/68 mm Hg, pulse is 102/min, and respirations are 20/min. His left femur is tender to palpation 3 cm above the left knee, and there is marked soft tissue swelling. A plain film of his left leg is normal. A bone scan shows increased uptake around the metaphysis of the left femur. Which of the following is the most likely pathogen?

665. A 20-month-old presents to the office with a 2-day history of a harsh, barking cough. His mother states that the cough sounds like a seal. She also states he has not had any fever, although he had a runny nose earlier in the week. On examination, he is notably hoarse with inspiratory stridor. He is not drooling and is sitting on his mother's lap comfortably. The rest of his examination is within normal limits. Which of the following is the most likely diagnosis?

666. A mother arrives to the clinic with her three children (ages 2 months, 18 months, and 36 months). The 18-month-old has an intensely pruritic scalp, especially in the occipital region, with 0.5-mm lesions noted at the base of hair shafts, as shown in the picture. Which of the following therapies should be avoided in this situation?

667. An infant born at term to a 22-year-old woman has a weak cry and is cyanotic at birth. His fingertips and oral mucosa appear blue. His blood pressure is 80/40 mmHg and his heart rate is 140/min. Chest x-ray shows clear lung fields bilaterally. PaO2 measured by arterial cannulation is 38 mmHg, and improves only minimally on 100% inspired oxygen. Which of the following is the best next step in managing this patient?

668. An 18-year-old male undergoes elective hernia repair. During the operation, he suffers considerable blood loss, and receives a blood transfusion. He then experiences an anaphylactic transfusion reaction. He is resuscitated and further hospital course is uncomplicated. His past medical history is significant for recurrent sinopulmonary infections and intermittent episodes of diarrhea since childhood. Which of the following is the most likely cause of his symptoms?

669. An 8-month-old previously preterm infant with bronchopulmonary dysplasia presents to the emergency department with lethargy. His regular medications include furosemide and spironolactone. His temperature is 37.4 C (99.3 F), blood pressure is 68/32 mm Hg, pulse is 110/min, and respirations are 10/min. He has poor skin turgor and dry mucous membranes. Laboratory chemistry evaluation reveals: sodium, 131 mEq/L; potassium, 3.0 mEq/L; chloride, 84 mEq/L; bicarbonate, 38 mEq/L; blood urea nitrogen, 36 mg/dL; and creatinine, 0.4 mg/dL. An arterial blood gas shows pH, 7.52; PaCO2, 49 mm Hg; and PaO2, 92 mm Hg. Which of the following is the most likely explanation for these findings?

670. A 4-year-old girl is brought to the physician by her mother who is concerned because her child has a vaginal discharge. Starting 2 days ago, the child began scratching her vulva and complaining of burning with urination. The child is otherwise healthy and has never had a similar problem. Examination reveals normal structural anatomy for a 4-year-old girl. There is no evidence of atrophy. There is an inflammatory erythema on the medial aspects of the labia majora and excoriations. There is a mucous discharge with a few flecks of blood intermixed. Which of the following is the most likely cause of a vaginal discharge in this patient?

671. A 1-year-old child presents with failure to thrive, frequent large voids of dilute urine, excessive thirst, and three episodes of dehydration not associated with vomiting or diarrhea. Over the years, other family members reportedly have had similar histories. Which of the following is the most likely diagnosis?

672. A 6-month-old infant has poor weight gain, vomiting, episodic fevers, and chronic constipation. Laboratory studies reveal a urinalysis with a pH of 8.0, specific gravity of 1.010, 1+ glucose, and 1+ protein. Urine anion gap is normal. Serum chemistries show a normal glucose and a normal albumin with a hyperchloremic metabolic acidosis. Serum phosphorus and calcium are low. What is the best diagnosis to explain these findings?

673. A 2-year-old girl is taken to a pediatrician because she has developed a rash and seems unusually unsteady when she tries to walk. Physical examination demonstrates a diffuse rash on body parts exposed to sun. Also noted are short stature, possible mental retardation, and ataxia. Screening studies demonstrate increased total amino acids in the urine. Which of the following is the most likely diagnosis?

674. A 24-month-old girl is brought to the pediatrician's office for evaluation because her mother noticed a yellowish discharge on the girl's underwear for the past 3 days. She had no fever, but her mother said she has been fussier recently. On physical examination, the girl is appears excessively anxious about contact with the physician. Her introitus is inflamed, and the hymeneal edge is jagged at the 8 o'clock position. A vaginal culture is taken. Which of the following organisms, if isolated from the vaginal vault, would constitute the most definitive evidence of sexual abuse?

675. You are called to the delivery room to evaluate an infant born at 28-weeks gestational age. The infant is tachypneic and cyanotic. Examination reveals intercostal and subcostal retractions along with nasal flaring. Lungs have coarse breath sounds bilaterally. After initial resuscitation, the patient is given respiratory support with continuous positive airway pressure and admitted to the neonatal intensive care unit. The patient's respiratory status continues to worsen over the next 24 hours. A chest radiograph from the patient is shown below. In addition to prematurity, which of the following is a risk factor for the development of this disease?

676. A 10-year-old boy, the star pitcher for the Salt Lake City Little League baseball team, had a sore throat about 2 weeks ago but did not tell anyone because he was afraid he would miss the play-offs. Since several children have been diagnosed with rheumatic fever in the area, his mother is worried that he may be at risk as well. You tell her that several criteria must be met to make the diagnosis but the most common finding is which of the following?

677. You are asked to evaluate an infant born vaginally 3 hours previously to a mother whose only pregnancy complication was poorly controlled gestational diabetes. The nursing staff noticed that the infant was breathing abnormally. On examination, you find that the infant is cyanotic, has irregular, labored breathing, and has decreased breath sounds on the right side. You also note decreased tone in the right arm. You provide oxygen and order a stat portable chest radiograph, which is normal. Which of the following studies is most likely to confirm your diagnosis?

678. A 6-year-old female is brought to the physician with a rash and joint pains. Her mother reports that she has been previously healthy except for a sore throat a few weeks ago. One week ago, the patient developed pain in her knees. The knee pain resolved after a few days, but now her ankles and wrists are tender. She has also developed a pink rash on her trunk that is non-pruritic. Vital signs are temperature 38.3 0c (101 0F), pulse 85/min, and respiratory rate 20/min. On examination, there is pain and stiffness during manipulation of the wrists and ankles. A faint, erythematous, centrifugal rash on her trunk and proximal limbs is present. Laboratory studies show: Complete blood count Hemoglobin 12.5 g/dL MCHC 32% MCV 85 fl Reticulocyte count 0.1% Platelet count 200,000/mm3 Leukocyte count 6,500/mm3 Neutrophils 56% Eosinophils 1% Lymphocytes 33% Monocytes 10% C-reactive protein 3.5 mg/dL Erythrocyte sedimentation rate 38 mm/hr Which of the following is the most likely diagnosis?

679. A 14-year-old African-American girl presents to the ER with a mild fever and severe right-sided thigh pain. She is agitated and requests quick pain relief. Her heart rate is 120/min and blood pressure is 120/70 mmHg. She says that she had a similar episode one year ago and was placed in the hospital for intravenous pain management. Her brother had similar episodes and died of an infection at 10 years of age. Which of the following would you most expect to see on this patient's peripheral blood smear?

680. A 9-year-old African-American boy is brought to ER with high fever, poor appetite, and irritability. His heart rate is 140/min and his blood pressure is 80/60 mmHg. He has been hospitalized several times before for poorly localized abdominal pain. He also has a history of hematuria. The boy has not received several routine vaccinations because his mother is afraid that they will cause autism. His hematocrit is 22% and the reticulocyte count is 12%. The patient dies several hours after the admission. This patient's death may have been prevented by:

681. A 10-month-old infant has poor weight gain, a persistent cough, and a history of several bouts of pneumonitis. The mother describes the child as having very large, foul-smelling stools for months. Which of the following diagnostic maneuvers is likely to result in the correct diagnosis of this child?

682. A 3-year-old girl is admitted with the x-ray shown below. The child lives with her parents and a 6-week-old brother. Her grandfather stayed with the family for 2 months before his return to the West Indies 1 month ago. The grandfather had a 3-month history of weight loss, fever, and hemoptysis. Appropriate management of this problem includes which of the following?

682. A 3-year-old girl is admitted with the x-ray shown below. The child lives with her parents and a 6-week-old brother. Her grandfather stayed with the family for 2 months before his return to the West Indies 1 month ago. The grandfather had a 3-month history of weight loss, fever, and hemoptysis. Appropriate management of this problem includes which of the following?

682. A 3-year-old girl is admitted with the x-ray shown below. The child lives with her parents and a 6-week-old brother. Her grandfather stayed with the family for 2 months before his return to the West Indies 1 month ago. The grandfather had a 3-month history of weight loss, fever, and hemoptysis. Appropriate management of this problem includes which of the following?

682. A 3-year-old girl is admitted with the x-ray shown below. The child lives with her parents and a 6-week-old brother. Her grandfather stayed with the family for 2 months before his return to the West Indies 1 month ago. The grandfather had a 3-month history of weight loss, fever, and hemoptysis. Appropriate management of this problem includes which of the following?

683. A previously healthy 18-month-old male comes to the physician for evaluation of fever. His mother reports that he has had a fever ranging from 1 02.2 0F (39.0 0c) to 104.0 0F (40.0 0c) for the past five days. He has also become increasingly irritable with decreased appetite. His mother reports that he does continue to take some liquids. There are no known sick contacts. On examination, the infant's temperature is 102.5 0F (39.2 0C), pulse is 120/min, and respiratory rate is 20/min. He is irritable during the examination. There is conjunctival erythema bilaterally, with serous drainage from both eyes. His oropharynx is erythematous and his lips are fissured. There is a 2 cm anterior cervical lymph node palpable on the right side. His neck is otherwise supple and he is able to flex his chin to his chest without difficulty. There is mild abdominal tenderness to palpation. His hands and feet are slightly erythematous and edematous and there is a maculopapular rash on the trunk. Which of the following is the most likely diagnosis?

683. A previously healthy 18-month-old male comes to the physician for evaluation of fever. His mother reports that he has had a fever ranging from 1 02.2 0F (39.0 0c) to 104.0 0F (40.0 0c) for the past five days. He has also become increasingly irritable with decreased appetite. His mother reports that he does continue to take some liquids. There are no known sick contacts. On examination, the infant's temperature is 102.5 0F (39.2 0C), pulse is 120/min, and respiratory rate is 20/min. He is irritable during the examination. There is conjunctival erythema bilaterally, with serous drainage from both eyes. His oropharynx is erythematous and his lips are fissured. There is a 2 cm anterior cervical lymph node palpable on the right side. His neck is otherwise supple and he is able to flex his chin to his chest without difficulty. There is mild abdominal tenderness to palpation. His hands and feet are slightly erythematous and edematous and there is a maculopapular rash on the trunk. Which of the following is the most likely diagnosis?

684. You are seeing a 4-year-old girl with the physical examination finding shown below. She has no significant past history. The most appropriate management is which of the following?

684. You are seeing a 4-year-old girl with the physical examination finding shown below. She has no significant past history. The most appropriate management is which of the following?

685. At the 2-week checkup of a term female infant, the mother reports a grayish and sometimes bloody vaginal discharge since birth. The infant’s mother and grandmother are the only caretakers. Examination of the external genitalia reveals an intact hymen with a thin grayish mucous discharge. Which of the following is the most appropriate next step?

685. At the 2-week checkup of a term female infant, the mother reports a grayish and sometimes bloody vaginal discharge since birth. The infant’s mother and grandmother are the only caretakers. Examination of the external genitalia reveals an intact hymen with a thin grayish mucous discharge. Which of the following is the most appropriate next step?

686. A 4196 g (9 lb 4 oz) infant is delivered via vaginal delivery to a 31-year-old mother with gestational diabetes. The delivery was complicated by shoulder dystocia. He is taken to the newborn nursery where his initial plasma glucose level is 20 mg/dL. The initial spun hematocrit is 65%. Which of the following congenital anomalies is this baby most likely to have?

686. A 4196 g (9 lb 4 oz) infant is delivered via vaginal delivery to a 31-year-old mother with gestational diabetes. The delivery was complicated by shoulder dystocia. He is taken to the newborn nursery where his initial plasma glucose level is 20 mg/dL. The initial spun hematocrit is 65%. Which of the following congenital anomalies is this baby most likely to have?

687. A 2-week-old infant is brought to the office for a newborn visit. His mother states that the he has been a very slow eater and that he is constipated, not having had a bowel movement in 3 days. On physical examination, the infant has poor muscle tone, an enlarged tongue, an umbilical hernia, an enlarged anterior fontanelle, and hypothermia. He also looks slightly jaundiced, with slightly dry skin and brittle hair. Which of the following is the most likely diagnosis?

687. A 2-week-old infant is brought to the office for a newborn visit. His mother states that the he has been a very slow eater and that he is constipated, not having had a bowel movement in 3 days. On physical examination, the infant has poor muscle tone, an enlarged tongue, an umbilical hernia, an enlarged anterior fontanelle, and hypothermia. He also looks slightly jaundiced, with slightly dry skin and brittle hair. Which of the following is the most likely diagnosis?

688. A 4-year-old male is brought to the physician with fever and headache. His symptoms began two days ago with low-grade fever, cough, and congestion. Last night, he developed a temperature of 102 F (38.9 C) and became fussy and less active. Today, he is crying and complaining of a headache. His parents report that he has vomited twice today. In the office, his temperature is 102.5 F (39.o c), pulse is 110/min, and respiratory rate is 20/min. On examination, he is irritable and shows signs of photophobia. His oropharynx is erythematous. Nuchal rigidity is present and when the neck is flexed, the patient flexes his lower extremities. The remainder of the physical examination is normal. Lumbar puncture is performed and the results are shown below. CSF Glucose 60 mg/dL Protein 80 mg/dL RBC 10/mm3 WBC 100/mm3 Neutrophils 10% Lymphocytes 70% Monocytes 20% Gram stain negative Which of the following organisms is most likely responsible for this patient's presentation?

688. A 4-year-old male is brought to the physician with fever and headache. His symptoms began two days ago with low-grade fever, cough, and congestion. Last night, he developed a temperature of 102 F (38.9 C) and became fussy and less active. Today, he is crying and complaining of a headache. His parents report that he has vomited twice today. In the office, his temperature is 102.5 F (39.o c), pulse is 110/min, and respiratory rate is 20/min. On examination, he is irritable and shows signs of photophobia. His oropharynx is erythematous. Nuchal rigidity is present and when the neck is flexed, the patient flexes his lower extremities. The remainder of the physical examination is normal. Lumbar puncture is performed and the results are shown below. CSF Glucose 60 mg/dL Protein 80 mg/dL RBC 10/mm3 WBC 100/mm3 Neutrophils 10% Lymphocytes 70% Monocytes 20% Gram stain negative Which of the following organisms is most likely responsible for this patient's presentation?

689. A 12-year-old boy is brought to the emergency department with a temperature of 39.1 C (102.4 F) at home, difficulty speaking, and odynophagia for 2 days, Physical examination reveals marked erythema of the right tonsil pillar and edema of the uvula with deviation to the left. In addition to anaerobic bacteria, which of the following organisms is most likely to be isolated from a tonsillar pillar aspirate?

689. A 12-year-old boy is brought to the emergency department with a temperature of 39.1 C (102.4 F) at home, difficulty speaking, and odynophagia for 2 days, Physical examination reveals marked erythema of the right tonsil pillar and edema of the uvula with deviation to the left. In addition to anaerobic bacteria, which of the following organisms is most likely to be isolated from a tonsillar pillar aspirate?

690. A neonate is noted to have many abnormalities, a number of which are located in the midline. The infant has cleft lip and cleft palate. His eyes are very small and have fissures of the iris, shallow supraorbital ridges, and slanted palpebral fissures. He is deaf, and the ears are low set and malformed. Each hand has six fingers and a simian crease. Which of the following congenital abnormalities of the brain is particularly likely to be present in this infant?

691. A 4-year-old boy, recently adopted through an international adoption service, is noted to have intermittent watery diarrhea, nausea, belching, and abdominal pain. His weight is less than the fifth percentile for his age. Which of the following studies would be most helpful in making the diagnosis?

692. A 5-month-old child regularly regurgitates a large portion of her feeds. A pH probe study showed significant periods of low esophageal pH. The child has normal growth and no other significant past medical history. Which of the following is the best management at this point?

693. A 7 -year-old boy is brought to your office with a mild fever and neck swelling. His mother says that the boy has been complaining of neck pain for a couple of days and she noticed a tender neck lump yesterday. All of his vaccinations are up-to-date. He has no known allergies. Physical examination reveals a tender and fluctuant anterior cervical mass. Which of the following is the best medication for this patient?

694. A 21-year-old female, G1P0, who recently emigrated from Zimbabwe presents for prenatal counseling in her 34th week of pregnancy. She received no prenatal care. Ultrasound evaluation reveals lower-than-normal fetal length and markedly reduced fetal head size. Which of the following could have prevented this condition?

695. A 4-week-old infant presents with tachycardia, tachypnea, and poor weight gain. His arterial blood gas shows a pH of 7.34, a PaCO2 of 41 mm Hg, and a PaO2 of 74 mm Hg. A chest radiograph shows cardiomegaly. Echocardiography reveals a structurally normal heart, left ventricular dilatation, a left ventricular ejection fraction of 20%, and mild mitral and tricuspid regurgitation. IV administration of which of the following medications is the best initial step in management of this patient?

696. A 12-year-old child is brought to his pediatrician for a routine health maintenance visit. He has been well except for occasional attacks of asthma and has met all development milestones. His immunizations are up to date. He occasionally uses theophylline for his asthma. Physical examination is remarkable for a blood pressure of 150/90 mm Hg in both arms. Which of the following is the most likely cause of his hypertension?

697. One of your asthmatic patients arrives for a checkup. The mother reports that the child seems to need albuterol daily, especially when exercising, and she has coughing fits that awaken her from sleep about twice a week. Her grandmother had recommended a Chihuahua as a “cure” for her asthma, but her mother has seen no difference since the arrival of the pet. Appropriate treatment measures would include which of the following?

698. An infant is brought to the office for health maintenance visit. On examination, the infant turns when her name is called. She is able to say "mama." Her mother mentions that she also says "dada" at home. She is able to look for her mother when she gets frightened. She also waves bye-bye to the doctor when the doctor steps out of the examination room. What age of this child is most consistent with these developmental milestones?

699. A 3-month-old infant is brought to the emergency department for severe vomiting over the past 6 hours. The mother tells the physician that she has vomited at least 4 times during this period. She also noticed the infant was having difficulty feeding for 2 days. On examination, she is very fussy, and there is a swelling over the left side of the head. CT of the head shows a skull fracture of the left parietal bone with no evidence of intracranial damage. The mother explains that the baby rolled off the sofa onto the floor yesterday. Which of the following is the most appropriate next step in management?

700. A 5-year-old boy is brought to the emergency department due to general malaise and a swollen scrotum. His mother noticed the swollen scrotum today, and is sure that "it was not there yesterday." He had a low-grade fever and a cough two weeks ago, and "hasn't been himself ever since." He has no significant past medical history. On examination, he looks ill and lethargic. He has palpable purpura on his buttocks and lower legs. He has a swollen right scrotum which is slightly tender to palpation, and his abdomen is moderately tender to palpation. Urinalysis reveals the presence of a small amount of blood and protein. He is subsequently admitted for observation. Which of the following adverse outcomes is he most likely to develop?

701. A term neonate develops apnea, tachypnea, and seizures in the first 2 hours of life. The infant is large for gestational age and appears obese. Physical examination is otherwise unremarkable. Serum studies demonstrate a blood glucose level of 30 mg/dL. The mother most likely has which of the following conditions?

702. You receive a call from the parents of a 1 year old who is due for his well-child visit next week. They have just received a letter from their daycare center that an employee has hepatitis A. Which of the following is the best treatment plan?

703. A 4-year-old child was brought in for evaluation of sleep problems. He cried and screamed within an hour of falling asleep. He seemed disoriented and confused; he did not seem aware of his parents’ presence. They were unable to arouse him to comfort him. This resolved spontaneously, and he had no recollection of the event the next morning. You informed the parents that he was most likely experiencing which of the following?

704. Varicella vaccination is a live virus vaccine. It is generally not recommended in immunocompromised patients. Which of the following is an exception to this rule?

705. A male infant was found to be jaundiced 12 hours after birth. At 36 hours of age, his serum bilirubin was 18 mg/dL, hemoglobin concentration was 12.5 g/dL, and reticulocyte count 9%. Many nucleated RBCs and some spherocytes were seen in the peripheral blood smear. The differential diagnosis should include which of the following?

706. On a routine well-child examination, a 1-year-old boy is noted to be pale. He is in the 75th percentile for weight and the 25th percentile for length. Results of physical examination are otherwise normal. His hematocrit is 24%. The answer to which of the following questions is most likely to be helpful in making a diagnosis?

707. A parent brings in a 5-year-old boy being treated for acute lymphocytic leukemia (ALL). He states a friend who is staying with them at their home has just come down with chicken pox. Your patient has not had chicken pox or received immunization with varicella vaccine. What is the appropriate treatment?

708. A young mother claims that her 4-week-old child sleeps best on his stomach. You tell her that the safest sleep position for infants is which of the following?

709. A 4-year-old boy is seen in the office for a general check-up. The child appears well nourished and has normal developmental milestones. His temperature is 36.6 C (98 F), pulse rate is 80/min, and blood pressure is 110/70 mmHg. On abdominal palpation, there is a lobular right-sided flank mass, and the kidneys are palpable bilaterally. What is the most likely cause of the flank mass in this child?

710. A 12-year-old boy is brought to the office by his mother due to a two-week history of generalized edema which is gradually progressing. His past medical history is insignificant. He is not taking any medications. His blood pressure is 110/80 mmHg, pulse is 85/min, respirations are 18/min, and temperature is 36.7C (98F). The laboratory findings are as follows: Serum sodium 140 mEq/L Serum potassium 3.7 mEq/L Serum albumin 2.1 g/dl Serum globulin 6.0 g/dl Serum creatinine 1.0 mg/dl Urinalysis reveals proteinuria 3+. What is the best next step in the management of this patient?

711. A 2-year-old child in shock has multiple nonblanching purple lesions of various sizes scattered about on the trunk and extremities; petechiae are noted, and oozing from the venipuncture site has been observed. The child’s peripheral blood smear is shown below. Clotting studies are likely to show which of the following?

712. A 10-year-old boy is admitted to the hospital because of bleeding. Pertinent laboratory findings include a platelet count of 50,000/L, prothrombin time (PT) of 15 seconds (control 11.5 seconds), activated partial thromboplastin time (aPTT) of 51 seconds (control 36 seconds), thrombin time (TT) of 13.7 seconds (control 10.5 seconds), and factor VIII level of 14% (normal 38%-178%). Which of the following is the most likely cause of his bleeding?

713. A 5-month-old boy is brought to the office for a mass in his left groin area. The infant is on the examination table, quietly sucking on his pacifier. On examination, there is a fluid-filled sac that does not reach the inguinal ring and transilluminates well. Which of the following is the most likely diagnosis?

714. A 9-year-old girl is brought to the clinic with complaints of fatigue, abdominal pain and low grade fever. Four days ago her mother noticed a red rash on the tops of her daughter's feet, which has now spread to her thighs and buttocks. The rash was initially small red dots, but has now become patches. Her daughter subsequently developed periumbilical, cramping, abdominal pain. Review of systems is positive only for a respiratory viral illness three weeks ago. Her temperature is 37.7 C (99.8 F), pulse is 96/min, and respirations are 18/min. Abdominal examination is remarkable for tenderness to palpation near the umbilicus, but the abdomen is otherwise soft, with no rebound or guarding, and no organomegaly. Raised, palpable purpuric lesions are present on the buttocks and thighs. The ankles are tender and edematous bilaterally. Complete blood count reveals a leukocyte count of 9,000/mm3. Her hemoglobin 12. 6 g/dL, and platelets are 325,000/mm3. Serum electrolytes are normal. Which of the following is her urinalysis most likely to reveal?

715. A 17-year-old adolescent comes to your office seeking help for “ heavy” menses. Your review of systems also reveals weekly epistaxis. Her only significant past history includes a tonsillectomy at age 6 after which she required blood transfusion for excessive bleeding. Her family history includes several people who seem to bleed and bruise more easily than others. The patient’s mother required a hysterectomy after child birth for excessive hemorrhage. You order a variety of laboratory tests. The patient has a hemoglobin of 6.5 mg/dL with an MCV of 60%; her platelet count is 350,000/L. Her von Willebrand antigen and her von Willebrand factor (vWF) activity (ristocetin cofactor activity) are decreased. Her vWF is reported as normal but in decreased amounts. You have been unable to reach her to report the findings, but when she calls about 1 week later she reports she is having a mild to moderate nosebleed. You initiate therapy with which of the following?

716. A 6-month-old infant is taken to the emergency department because he had a seizure. Physical examination demonstrates premature closure of cranial sutures and markedly bowed legs. Laboratory studies demonstrate low serum phosphate levels, with normal vitamin D and parathyroid hormone levels. Urinalysis shows high phosphate levels, but no increased excretion of glucose, amino acids, or protein. The child's maternal grandfather had crippling bone disease, and his mother has mild bowing of the legs. Which of the following is most likely diagnosis?

717. A 2-year-old girl is brought to the emergency department with a fever, chills, poor appetite, and vomiting. On examination, she is irritable and diaphoretic. Her temperature is 39.2 C (102.5 F), blood pressure is 80/48 mm Hg, pulse is 88/min, and respirations are 17/min. She is tender at the left costovertebral angle. Initial laboratory tests show the following: Leukocyte count 16,300/mm3 Hemoglobin 12.5 g/dL Platelet count 245,000/mm3 Blood urea nitrogen 6 mg/dL Creatinine 0.5 mg/dl Urinalysis is positive for leukocyte esterase and nitrite, with 150 white blood cells/hpf. After TV antibiotic administration and stabilization, what is the most appropriate diagnostic study?

718. An 8-year-old male presents to the emergency department with decreased mental status. His mother states that she has noticed he has been drinking and urinating more frequently over the past several weeks. He was hard to wake up this morning and complained of abdominal pain. Physical examination reveals an afebrile drowsy male with clear airways and mild tachycardia. Mucous membranes are dry and his lips are cracked. His abdomen is mildly tender to palpation diffusely, but there is no rebound or guarding. Laboratory evaluation reveals a glucose of 560 mg/dL and potassium of 5.9 mEq/L.An arterial blood gas analysis reveals a pH of 7.18. A urinalysis is positive for ketones and glucose. CT scan of the abdomen is normal. A chest x-ray film is clear. Two hours after initiation of treatment the physician adds potassium to the patient's IV fluids. Which of the following best explains this therapeutic decision?

719. An 8-month-old girl is brought to the clinic for a well-baby checkup. Her antenatal and birth histories are unremarkable. Her vital signs are stable, and all developmental milestones are appropriate. On examination, a head tilt is noted. Ophthalmoscopic examination reveals a red reflex and normal corneal light reflex. The cover test reveals moderate esodeviation of the left eye. What is the most appropriate next step in the management of this patient?

720. A 6-year-old girl is brought to the office for the evaluation of "passing smoky urine." She recently had a sore throat. Her blood pressure is 150/100 mmHg. There is swelling of the face and extremities. Urinalysis reveals many red blood cells, red blood cell casts and 1 + proteinuria. Her serum C3 level and CH 50 are low. Her C4 1evel is normal. Her antistreptolysin-a (ASO) titer is 1,024 Todd units (normal ≤ 166 Todd units). In this patient, which of the following abnormal findings is most likely to become normal within 8 to 12 weeks?

721. The mother of a 3-day-old infant brings her child to your office for an early follow-up visit. The mom notes that the child has been eating well, has had no temperature instability, and stools and urinates well. She notes that over the previous 3 days the child has had a progressive rash on the face as pictured here. Which of the following is the most likely diagnosis?

722. A 2-year-old child (A) presents with a 4-day history of a rash limited to the feet and ankles. The papular rash is both pruritic and erythematous. The 3-month-old sibling of this patient (B) has similar lesions also involving the head and neck. The most appropriate treatment for this condition includes which of the following?

723. An 8-hour-old infant develops increased respiratory distress, hypothermia, and hypotension. A complete blood count (CBC) demonstrates a white blood cell (WBC) count of 2500/μL with 80% bands. The chest radiograph is shown below. Which of the following is the most likely diagnosis?

724. A 3-year-old child is taken to a pediatrician because he develops burning pain, erythema, and swelling minutes after being exposed to the sun. Physical examination demonstrates erythema with swelling of the hands and arms. The skin is thickened on the backs of the hands but does not show blistering or scarring. Which of the following is the most likely diagnosis?

725. A 16-year-old girl has had a fever, vomiting, and watery diarrhea for the past 24 hours. She also complains of intermittent abdominal pain and generalized myalgia. On examination, she is slightly lethargic. Her temperature is 39.4 C (103 F), blood pressure is 75/50 mm Hg, and pulse is 150/min. Her conjunctivae and pharynx are hyperemia. She has a generalized erythematous maculopapular rash that spares the wrists. Which of the following will be the most appropriate treatment?

726. An 8-month-old infant, who is up-to-date with his immunizations, is brought to the clinic by his mother. The mother states that she overheard other mothers talking about a varicella vaccination that their children have received. She does not want her son to have the chickenpox virus and therefore, wants him to receive the vaccine today. The physician explains that the infant has not yet reached the recommended age for the vaccine. If this visit is in November, when is the earliest that this patient can return for the varicella vaccine?

727. An 11-year-old girl is brought to the office by her mother due to headaches for the last 4 hours. The headaches are bifrontal, and are accompanied by nausea, vomiting, and sensitivity to light and noise. It is her second episode, and both episodes were preceded by dark spots in her visual field. The first episode was 2 weeks ago. She doesn't report any numbness or tingling in her extremities, and no behavioral change or decline in school performance was noted. Her vital signs are stable, and she is afebrile. The physical examination is normal. What is the most appropriate next step in the management of this patient?

728. A previously healthy one-year-old child is brought to the physician for a routine wellness visit. Her parents report that she drinks six glasses of whole milk a day, but is a very picky eater. She is developmentally appropriate. Her parents are concerned that she might be anemic because she frequently eats ice and sometimes dirt. On examination, her temperature is 88.6F (37 C), pulse is 118/min, and respiratory rate is 21 /min. Her height and weight are both at the 50th percentile for her age. She appears well nourished and her physical examination is unremarkable. Laboratory findings include the following. Complete blood count Hemoglobin 10.5 g/dL MCV 70 fl Reticulocytes 1.0% Platelets 250,000/mm3 Leukocyte count 6,500/mm3 Neutrophils 56% Lymphocytes 33% Monocytes 10% Which of the following is the most appropriate next step in the management of this child?

729. An inner city family has been using a neighbor to care for their 3-year-old child while the parents work. The neighbor is diagnosed with pulmonary tuberculosis. PPD test of the 3-year-old is negative. Which of the following is indicated for the 3-year-old?

730. A 7 -year-old male child is brought to the office due to decreased urine output and lethargy for the past week. His birth and past medical histories are insignificant. His immunizations are up-to-date. Examination reveals no abnormalities. His BUN and creatinine levels are elevated. What is the most appropriate next step in the management of this patient?

731. A 7 -day-old male infant is brought by his mother complaining of decreased movements of his right arm. She denies any trauma or fall. Pregnancy was uneventful, but delivery was complicated with shoulder dystocia. Examination reveals the presence of crepitus and bony irregularity over the clavicular area and Mora reflex is absent on the right. Which of the following is the most appropriate management?

732. An infant born at 35 weeks’ gestation to a mother with no prenatal care is noted to be jittery and irritable, and is having difficulty feeding. You note coarse tremors on examination. The nurses report a high-pitched cry and note several episodes of diarrhea and emesis. You suspect which of the following?

733. A previously healthy full-term infant has several episodes of duskiness and apnea during the second day of life. Diagnostic considerations should include which of the following?

734. A 3-year-old girl is brought to the pediatrician with complaints of abdominal pain and fever. Her mother states that the fever started 2 days ago, with the highest temperature being 39.0 C (102.2 F). She has had no vomiting or diarrhea. The mother states that her daughter has been complaining of pain on urination. On examination, she is tender in her lower abdomen, and there is some right-sided costovertebral angle tenderness. A urinalysis confirms the suspicion of a urinary tract infection. Which of the following would be the most appropriate diagnostic procedure?

735. A very concerned mother brings a 2-year-old child to your office because of two episodes of a brief, shrill cry followed by a prolonged expiration and apnea. You have been following this child in your practice since birth and know the child to be a product of a normal pregnancy and delivery, to be growing and developing normally, and to have no chronic medical problems. The first episode occurred immediately after the mother refused to give the child some juice; the child became cyanotic, unconscious, and had generalized clonic jerks. A few moments later the child awakened and had no residual effects. The most recent episode (identical in nature) occurred at the grocery store when the child’s father refused to purchase a toy for her. Your physical examination reveals a delightful child without unexpected physical examination findings. Which of the following is the most likely diagnosis?

736. You are called to examine a 2-day old male infant due to difficulty in feeding. He becomes cyanotic and short of breath when he feeds, but turns pink when he cries. His prenatal, birth and family histories are unremarkable. His vital signs are normal. Chest auscultation is normal. His peripheral pulses are full and symmetric. What is the most likely diagnosis?

737. A 3-week-old female is brought into the emergency department with a fever and irritability. She was born after a normal pregnancy and delivery. Her mother had routine prenatal care and has no history of sexually transmitted infections. The infant's mother is 14 years old and the father is 17 years old. They are not married, and the father is not involved in the care of the infant. The infant lives with her mother and maternal grandparents at the maternal grandparents' home. You are concerned about meningitis and decide to do a lumbar puncture. The mother and maternal grandparents are present in the emergency department. Informed consent should be obtained from which of the following individuals?

738. You are seeing a 2-year-old child, brought by his father for a well-child examination. In providing age-appropriate anticipatory guidance, you should tell him which of the following?

739. A child can walk well holding on to furniture but is slightly wobbly when walking alone. She uses a neat pincer grasp to pick up a pellet, and she can release a cube into a cup after it has been demonstrated to her. She tries to build a tower of two cubes with variable success. She is most likely at which of the following age?

740. A neonate has an obviously abnormal foot. The foot is in a markedly plantar flexed position, with the sole facing the adjacent leg in a position of marked adduction. No other anomalies are noted on physical examination. Which of the following is the most likely diagnosis?

741. A mentally retarded 10-year-old boy presents with arthritis, nephrolithiasis, and progressive renal failure. Since his first years of life, he manifested peculiar neurologic abnormalities consisting of self-mutilative biting of the lips and fingers, choreoathetosis, and spasticity. Two male relatives on his mother's side presented with a similar condition and died in their teens. Which of the following is the most likely diagnosis?

742. A previously healthy 7-year-old girl comes to the office with complaints of episodic abdominal pain over the past several months. The pain is periumbilical and sharp but does not wake her from sleep or interfere with play. She has no fever, joint complaints, or constipation or diarrhea. Growth and development have been normal. The physical examination is within normal limits. Which of the following is the most likely diagnosis?

743. A 4-month-old male infant is brought to the office by his parents due to progressive lethargy, poor feeding, fatigue and increasing pallor for the past four weeks. His antenatal and birth histories are unremarkable. His diet consists mainly of breast milk. His immunizations are up-to-date. His mother's blood type is O+. Physical examination reveals a webbed neck, cleft lip, shielded chest, triphalangeal thumbs, and pale mucous membranes and conjunctivae. Cardiac auscultation reveals mild tachycardia and a systolic ejection murmur over the left upper sternal border. The initial investigations reveal the following: Hb 8 g/dl Ht 26% WBCs 7,000/mm3 Platelets 300,000 /mm3 Reticulocytes 04% MCV 104 fl Blood type A - Bilirubin direct 0.1 mg/dl Bilirubin total 1.0 mg/dl What is the most likely diagnosis?

744. A 15-year-old Caucasian male is brought to the office by his mother for the evaluation of a six-month history of unstable gait and speech difficulty which are getting worse over time. His past medical history is insignificant. He is not taking any medications, and denies smoking or alcohol consumption. His blood pressure is 120/70 mmHg and pulse is 80/min. Musculoskeletal examination showed scoliosis and feet deformity with 'hammer toes.' The neurologic examination showed dysarthria, dysmetria, nystagmus, and absence of deep plantar reflexes on lower extremities. What is the most common cause of death in this patient population?

745. Over the previous 2 to 3 weeks, a very active 13-year-old white boy is noted by his family to have developed deep pains in his leg that awaken him from sleep. The family brings him to your office with a complaint of a swelling over his distal leg, which he attributes to his being kicked while playing soccer about 1 week ago. He has had no fever, headaches, weakness, bruising, or other symptoms. A radiograph of the leg is shown below. Which of the following is the most likely explanation for his pain?

746. An 18-month-old child is brought to the emergency department by his mother due to a one-day history of lethargy and anorexia. He had a fever the whole day yesterday, which responded to Tylenol (Acetaminophen). He then developed a petechial rash over his entire body, which worsened in the last few hours. He is up-to-date with his immunizations, and is an otherwise healthy baby. On examination, he is drowsy and lethargic. He has neck stiffness and appears septic. He flexes his hips when his neck is flexed. What is the most likely organism responsible for the patient's symptoms?

747. You are called to examine a one-day-old male neonate who gradually developed cyanosis over the past few hours. The infant was delivered vaginally at full term, assisted with forceps, and weighed 9 lbs. The Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. Oxygen administration by mask does not relieve the cyanosis. Further examination reveals tachypnea, subcostal retractions, a normal S 1, single and loud S2, and no murmur. Which of the following is the most probable cause of the infant's cyanosis?

748. A 9-month-old, chubby, healthy-appearing boy is brought to the pediatrician because of episodes of colicky abdominal pain and blood-tinged stools. The pain lasts from 1 to 10 minutes and causes the infant to double up; he then appears normal until his next bout of colic. During the examination, the infant has another episode, at which time a vague mass can be felt on the right side of the abdomen, and the right lower quadrant has an "empty" feeling to deep palpation. Which of the following is the most appropriate initial step in management?

749. A 29-year-old woman presents to the delivery room in labor at 35 weeks' gestation with a temperature of 40 C (104 F). She lives on a dairy farm and is in the habit of drinking unpasteurized milk from her cows before sending it to the dairy. For the past 3 days she has been unable to attend to her chores because of fever, headache, mild diarrhea, and a general feeling of illness. When her amniotic membranes rupture, the fluid is dark, cloudy, and brownish-green. At birth, the infant has no malformations or edema, but is in severe respiratory distress. Which of the following is the most likely diagnosis?

750. A 4-year-old girl with sickle cell disease presents to the emergency department with a temperature of 39.6 C (103.2 F). Other than irritability, the physical examination is unremarkable. Laboratory evaluations reveal a white blood cell count of 18,200/mm3, with 88% polymorphonuclear neutrophils, 10% lymphocytes, and 2% monocytes, and a hemoglobin of 7.6 g/dL. Which of the following is the most appropriate next step in management?