USMLE Pediatry For Student Diagnostic Pédiatrie P2 190 QCM

201) A 2-year-old patient arrives late to your office with his father and a sign-language translator. They are very apologetic, but the father communicates that he had car trouble at his dialysis center and thus was late picking up the child from day care. The father is concerned about his child’s having intermittent red, bloody-looking urine. A gross inspection of the child’s urine in your office looks normal, but the dipstick demonstrates 3+ blood. Which of the following is the most likely cause of this child’s hematuria?

202) A 2-year-old boy is brought to the clinic by his mother because he is lethargic and not as active as the other kids on their block. He has difficulty walking and getting up, and he always appears tired. His mother thinks that she has a relative with a disorder that causes weakness. On examination, the child is alert but quiet. His calves appear hypertrophied. His reflexes are depressed. When he gets up from the floor, he uses his hands to climb on his legs to assume an upright position. What is the most likely diagnosis of this child?

203) A 2-month-old male infant is rushed to the emergency department by his baby sitter. She says that the baby became unresponsive and blue while feeding. The whole episode lasted 45-60 seconds, but the baby still appears pale. She denies any history of coughing or choking. On examination, the infant appears cyanotic and tachypneic. His blood pressure is 90/60 mm of Hg; his pulse rate is 155/min and regular. On auscultation, a harsh pansystolic murmur is noted at the left sternal border, along with a single S2. Hepatomegaly is noted. Pulse oximetry shows an oxygen saturation of 80%. Based on this history and physical examination, what is the most likely diagnosis?

205) During a routine well-child examination a 10-year-old girl reports that she has occasional headache, “racing heart,” abdominal pain, and dizziness. Her mother states that she has witnessed one of the episodes, which occurred during an outing at the mall, and reported the child to be pale and to have sweating as well. Other than some hypertension, she has a normal physical examination. Evaluation of this child is most likely to result in which of the following diagnoses?

208) A 6-year-old boy is brought to your practice by his paternal grandmother for his first visit. She has recently received custody of him after his mother entered the penal system in another state; she does not have much information about him. You note that the child is short for his age, has downslanting palpebral fissures, ptosis, low-set and malformed ears, a broad and webbed neck, shield chest, and cryptorchidism. You hear a systolic ejection murmur in the pulmonic region. His grandmother reports that he does well in regular classes, but has been diagnosed with learning disabilities and receives speech therapy for language delay. His constellation of symptoms is suggestive of which of the following?

209) A 2-week-old infant is noted to be jaundiced. The baby's stools are pale, and his urine darkly colored. Physical examination demonstrates hepatomegaly. Serum studies show elevations of AST, ALT, conjugated bilirubin, and unconjugated bilirubin. By 2 months of age, the baby is notably irritated by pruritus, has retarded growth, and has visible dilated veins in the periumbilical area. Ultrasound fails to demonstrate a gallbladder. Which of the following is the most likely diagnosis?

210) A mother brings her 7-year-old son to the clinic because, over the past several days, his urine has become pink and bis eyes have looked puffy. About 2 weeks ago, he missed school because of fever and a sore throat. On examination, the boy's blood pressure is 130/85 mm Hg, his eyelids and scrotum appear puffy, and he has 1+ tibial edema. No rashes are noted. Which of the following is the most likely diagnosis?

212) An otherwise healthy 7-year-old child is brought to you to be evaluated because he is the shortest child in his class. Careful measurements of his upper and lower body segments demonstrate normal body proportions for his age. Which of the following disorders of growth should remain in your differential?

213) A 4-year-old immigrant boy is brought by his mother to a Medical Camp for the Uninsured for the evaluation of his inflamed right eye. He has had a nasal discharge for the past 10 days. His brother has similar symptoms. His vital signs are stable. There are follicles and inflammatory changes in the conjunctiva of his right eye. The cornea shows neovascularization. What is the most likely diagnosis?

214) A previously healthy 7-year-old child suddenly complains of a headache and falls to the floor. When examined in the emergency room (ER), he is lethargic and has a left central facial weakness and left hemiparesis with conjugate ocular deviation to the right. Which of the following is the most likely diagnosis?

215) An irritable 6-year-old child has a somewhat unsteady but nonspecific gait. Physical examination reveals a very mild left facial weakness, brisk stretch reflexes in all four extremities, bilateral extensor plantar responses (Babinski reflex), and mild hypertonicity of the left upper and lower extremities; there is no muscular weakness. Which of the following is the most likely diagnosis?

217) A 6-year-old boy presents in clinic for a routine visit. Examination reveals coarse, dark pubic hair, an enlarged penis and testes, and acne of the face and upper back. His mother notes that he has a body odor similar to that of her teenage son after playing sports. The child is in file 99th percentile of height for his age group. Which of the following is the most likely diagnosis?

218) A 10-year-old girl is brought to a pediatrician because her mother notices that she stumbles frequency at night, even with adequate lighting. Visual field testing demonstrates a relatively narrow mid-peripheral ring scotoma. Ophthalmoscopy demonstrates dark pigmentation in a bone spicule configuration involving the equatorial retina. Additional findings include a waxy yellow appearance to the disk and narrowed retinal arteries. Which of the following is the most likely diagnosis?

219) A 6-week-old boy is brought to the physician because of a rash involving the diaper area. On examination, there are erythematous, slightly scaly patches covering the buttocks and the lower abdomen. Skin creases appear spared. The baby is otherwise healthy. Physical examination reveals no lymphadenopathy, fever, or other signs of organic illness. Which of the following is the most common cause of this condition?

220) A 3-year-old boy was bitten while teasing a neighborhood cat. On examination, there are two puncture wounds on the right hand and some superficial scratch marks. There is erythema, warmth, and induration around the puncture sites. Which of the following organisms most likely caused the infection?

221) A 2-year-old boy has had a purulent drainage from the right nostril for a week. He is afebrile and has had no associated symptoms, such as cough. Which of the following is the most likely diagnosis?

222) You are called to examine a male newborn because his first feeding caused him to choke, cough and regurgitate. He was born at term via normal vaginal delivery. On examination, he has excessive salivation, fine, frothy bubbles in the mouth, abdominal distention and rattling breath sounds. Radiographs of the chest and abdomen reveal bilateral atelectasis and gastric distension. Which of the following can best explain the above findings?

223) A 9-year-old boy is brought to the office by his parents due to headaches, vomiting and visual disturbances. One week ago, he began to experience headaches that were most prominent in the morning. He also became lethargic, and had a decreased appetite and decline in school performance. The pertinent physical findings include an unbalanced gait, trunk dystaxia, horizontal nystagmus, and papilledema. If this child had a medulloblastoma, which structure would most likely be affected?

224) A 7 -year-old girl is brought to the clinic by her mother due to a persistent postnasal drip and repeated episodes of a runny nose. In the winter, she experiences several episodes of upper respiratory tract infections, which last for two to three weeks at a time. She snores, and is unable to smell her favorite food. Her immunizations are up-to-date. On examination, she is mildly underweight for her age. She has a runny nose, and her nasal drainage is colorless and stringy. Nasal inspection reveals bilateral nasal polyps, and auscultation of the chest reveals coarse rales. What is the one condition that you would like to rule out in this child?

225) A 2-year-old boy is brought by his mother to the emergency department because of a high-grade fever which "does not go away" with acetaminophen. For the last four days, the child has been very irritable and is crying a lot. He is also pulling his ear and not eating well. He has been generally well, other than the occasional sore throat this season. His temperature is 38.8° C (102.2° F), blood pressure is 90/60 mm Hg, pulse is 119/min, and respirations are 24/min. He appears well nourished, but is irritable. Physical examination reveals enlarged cervical lymph nodes and splenomegaly. The tympanic membranes are inflamed. CBC shows: WBC 81,100mm3, Hemoglobin 8.0 g/dL, Hematocrit 25%, Platelets 16,000 mm3, Blast forms 80%, Prolymphocytes 10%, Lymphocytes 10%. The blast cells have condensed nuclear chromatin, small nucleoli and scant agranular cytoplasm. Subsequent histochemical staining reveals strongly positive periodic acid Schiff (PAS) reaction. No Auer rods were seen. Which of the following is the most likely diagnosis?

226) A young infant is noted to have developed constipation over the past week, and then facial diplegia and difficulty sucking and swallowing. The child has been colicky, and the maternal grandmother has been treating the child with a mixture of weak tea, rice water, and honey. Which of the following disorders is the most likely culprit in this child?

227) About 12 days after a mild upper respiratory infection, a 12-year-old boy complains of weakness in his lower extremities. Over several days, the weakness progresses to include his trunk. On physical examination, he has the weakness described and no lower extremity deep tendon reflexes, muscle atrophy, or pain. Spinal fluid studies are notable for elevated protein only. Which of the following is the most likely diagnosis in this patient?

228) A premature neonate develops respiratory distress syndrome several hours after birth. The infant is placed on a respirator and given other appropriate care. However, when the infant reaches a corrected gestational age of 36 weeks, he does not tolerate weaning from the ventilator. A chest x-ray film demonstrates alternating areas of hyperaeration and pulmonary scarring, resulting in parenchymal streaks and hyperexpanded areas. Which of the following is the most likely diagnosis?

229) A neonate has Down syndrome. Maternal hydrammos had been noted prenatally. After the first feeding, the infant has projectile vomiting with bile-stained vomitus. An x-ray film demonstrates a "double-bubble sign" in the abdomen. Which of the following is the most likely diagnosis?

230) A 10-year-old boy is brought to the office by his parents because he is developing dark facial hair, deepening of the voice and a rapid height increase. He also complains of persistent headaches which are resistant to over-the-counter analgesics for the past 2 weeks. He denies nausea, vomiting or visual disturbances. His medical history is unremarkable. Physical examination reveals coarse pubic and axillary hair. Other pertinent findings include lid retraction, paralysis of upward and downward gaze, and poor pupillary reaction to light. His deep tendon reflexes are normal, Babinski sign is negative, and there are no focal neurologic signs. What tumor is most likely responsible for this child's symptoms?

231) A 17-year-old girl comes to the clinic with several weeks of joint pain and rash. The joint pain is most prominent in the hands. She states that the pain is most severe in the morning and tends to improve over the day. She has noted some swelling of her fingers. She has also had a rash on her face that becomes more prominent when she is outdoors. She states that sunlight tends to bother her eyes. On further questioning, she states that she has not felt well for several months. She has had intermittent fever, has been more tired than usual, and has lost weight although she has not been restricting her diet. On physical examination, she looks tired. She has lost 5 lbs since her last visit 1 year ago. She has an erythematous rash on her cheeks. She has several shallow ulcers in her mouth. She has fusiform swelling of her fingers and pain with movement of her fingers. Which of the following is the most likely diagnosis?

232) A full-term newborn develops cyanosis a few hours after birth. Oxygen administration does not improve color or oxygen saturations. Which of the following is the most likely diagnosis?

233) A 6-year-old male presents to the physician with eyelid swelling. His mother noted an insect bite on his left cheek yesterday, and states that this morning his left eyelid was completely swollen shut and painful. He has not had a fever, fatigue, headache, or rhinorrhea. On examination, he is afebrile. The left eyelid is erythematous, tender to palpation, and swollen shut. When trying to clinically distinguish between preseptal and orbital cellulitis, which of the following findings is most likely to be seen with preseptal cellulitis?

234) A 4-year-old Caucasian boy is brought to his physician's office for a health maintenance exam. He will be starting preschool soon, and his parents want to make sure that he is in optimal health. The child has no complaints, and is generally happy. His medical history is significant for pneumonia as a newborn, and three episodes of otitis media since birth. He does not take any medications on a regular basis. His newborn screening test results are normal. His developmental milestones are at par with his age. He lives with his parents in a middle-class, suburban house built in 1981. Which of the following is the most appropriate next step for this child's primary care?

235) Initial examination of a full-term infant weighing less than 2500 g (5 lb, 8 oz) shows edema over the dorsum of her hands and feet. Which of the following findings would support a diagnosis of Turner syndrome?

236) While bathing her newly-received 2-year-old son, a foster mother feels a mass in his abdomen. A thorough medical evaluation of the child reveals aniridia, hypospadias, horseshoe kidney, and hemihypertrophy. Which of the following is the most likely diagnosis for this child?

237) A 7-day-old boy is admitted to a hospital for evaluation of vomiting and dehydration. Physical examination is otherwise normal except for minimal hyperpigmentation of the nipples. Serum sodium and potassium concentrations are 120 mEq/L and 9 mEq/L (without hemolysis), respectively; serum glucose is 40 mg/dL. Which of the following is the most likely diagnosis?

238) A 12-week-old female infant is brought to the office by her mother due to a three-week history of weakness, poor appetite, and choking spells during feeding. Other accompanying symptoms include excessive sleeping, constipation and apathy. Her prenatal history is unremarkable. She was delivered vaginally at 38 weeks of gestation. Her weight and length at birth were within normal range. She is exclusively breastfed. Her mother's family history is unremarkable. The identity and family history of her father are unknown. The pertinent physical findings include apathy, weakness, hypotonia, large tongue, sluggish movement, abdominal bloating, and an umbilical hernia. Based on the given information, what is the most likely diagnosis?

239) While making rounds in the newborn nursery, the nurses ask you to examine a 2-day-old infant who is not feeding well. The nurse reports that the infant is irritable, is not sleeping well, and has had several episodes of vomiting and loose stools today. A review of the maternal history reveals that she had poor prenatal care and the pregnancy was complicated by intrauterine growth restriction. On examination, the infant is diaphoretic and has a high-pitched cry. The infant is also noted to have occasional sneezing and is mildly tachypneic. No dysmorphic features are noted and the remainder of the examination is unremarkable. This infant's symptoms are most likely caused by prenatal exposure to which of the following?

240) A 10-year-old boy is brought to the emergency department due to abdominal pain and bloody diarrhea. The mother says that he was "fine" a few days ago, and then suddenly became ill. Physical examination shows a pale and jaundiced child. There is diffuse abdominal tenderness and 2+ pedal edema. Laboratory studies show anemia, thrombocytopenia and renal insufficiency. What is the most likely cause of the patient's symptoms?

241) A 16-year-old girl is brought to the office due to abdominal pain and bloody diarrhea for the past two days. Her immunizations are up to date. Her past medical history is unremarkable. On examination, she appears lethargic and weak. Her skin turgor is poor, face and extremities are swollen, and skin appears yellow. Abdominal examination shows moderate non-localized, abdominal pain. Laboratory studies show: Hb 64 g/dl, Hct 26.9%, Platelets 45,000/mm3, Creatinine 2.3 mg/dl, Total bilirubin 5.0 mg/dl. What is the most common complication of the patient's condition?

243) A 4-year-old boy, whose past medical history is positive for three urinary tract infections, presents with a blood pressure of 135/90 mm Hg. He is likely to exhibit which of the following symptoms or signs?

245) A 6-year-old boy is brought to the ER with a two-day history of difficulty walking. He is dragging his right leg and seems to have weakness in his right arm. He also complains of headaches. The family just emigrated from Eastern Europe. According to his parents, the child suffers from delayed growth compared to his peers and does not like to engage in active play. His lips and fingers turn blue when he cries. His vital signs today are a blood pressure of 100/70 mmHg, pulse of 90/min, temperature of 38.3 0C (102.0 0F), and respiratory rate of 22/min. Which of the following is most likely responsible for his current complaints?

247) A 4-year-old, apparently healthy child is examined by a pediatrician. The pediatrician hears a loud systolic ejection murmur with a prominent systolic ejection click. He also hears a soft, early diastolic murmur. Both murmurs are heard best at the upper right sternal border. ECG shows left ventricular hypertrophy. Which of the following is the most likely diagnosis?

248) A 19-year-old primiparous woman develops toxemia in her last trimester of pregnancy and during the course of her labor is treated with magnesium sulfate. At 38 weeks’ gestation, she delivers a 2100-g (4-lb, 10-oz) infant with Apgar scores of 1 at 1 minute and 5 at 5 minutes. Laboratory studies at 18 hours of age reveal a hematocrit of 79%, platelet count of 100,000/μL, glucose 41 mg/dL, magnesium 2.5 mEq/L, and calcium 8.7 mg/dL. Soon after, the infant has a generalized convulsion. Which of the following is the most likely cause of the infant’s seizure?

249) A 4-year-old child presents with an enlarged submandibular node that is 4 cm in diameter, nontender, and not fluctuant. The node has been enlarged for about 4 weeks, and there is no history of fever or contact with any person who was ill. A CBC is normal, and a Mantoux test with 5 tuberculin units of PPD shows 6 mm of induration. Which of the following is the most likely diagnosis?

250) A 7-month-old patient presents with a history of 3 days of fever to 104°F, which resolved the same day that an exanthem erupted. The exanthem is prominent on the neck and trunk. It is macular, with discrete lesions 3–5 mm in diameter. Which of the following is the most likely diagnosis?

251) A 3-year-old boy’s parents complain that their child has difficulty walking. The child rolled, sat, and first stood at essentially normal ages and first walked at 13 months of age. Over the past several months, however, the family has noticed an increased inward curvature of the lower spine as he walks and that his gait has become more “waddling” in nature. On examination, you confirm these findings and also notice that he has enlargement of his calves. Which of the following is the most likely diagnosis?

252) Your 6-year-old son awakens at 1:00 AM screaming. You note that he is hyperventilating, is tachycardic, and has dilated pupils. He cannot be consoled, does not respond, and is unaware of his environment. After a few minutes, he returns to normal sleep. He recalls nothing the following morning. Which of the following is the most likely diagnosis?

253) A 5-year-old febrile child presents with swelling of the right eyelid. Proptosis and limitation of ocular movements is noted. Which of the following is the most likely diagnosis?

254) A 10-year-old boy is brought in with a chief complaint of multiple colds. On further questioning, you elicit a history of chronic, clear nasal discharge with no seasonal variation. Other symptoms include sneezing, itching of the nose and eyes, as well as tearing and occasional eye redness. Some relief is obtained with an over-the-counter cold medicine containing antihistamine and a decongestant. His history suggests which of the following?

256) A 4-day-old infant presents with yellow discoloration of the skin and sclera. The baby was born at term by a normal vaginal delivery. Pregnancy was uncomplicated; there were no risk factors for sepsis and no history of maternal alcohol or drug use. The baby is breast-fed and has been nursing every 2 hours, about 10 minutes at each breast. The bilirubin level is 15 mg/dL (all unconjugated), the hematocrit is 45%, and the Coombs test is negative. Which of the following is the most likely diagnosis?

257) A previously healthy, active, 18-month-old African American child presents with unilateral nasal obstruction and foul-smelling discharge. The child’s examination is otherwise unremarkable. Which of the following is the most likely diagnosis?

258) A 7-month-old baby presents with a history of constipation for 1 month. He has one hard stool every week. He has been well otherwise. His physical examination is normal. Which of the following is the most likely cause of his problem?

259) A specific pattern of abnormalities has been identified among infants born to mothers who consume moderate-to-large amounts of alcohol during their pregnancies. Which of the following abnormalities is characteristic of these infants?

261) The parents of a previously healthy 2-year-old child note her to be pale and bring her to your clinic for evaluation. She currently has no fever, nausea, emesis, bone pain, or other complaints. Her examination is significant for pallor, tachycardia, and a systolic ejection murmur, but she has no organomegaly. Her complete blood count (CBC) reveals a hemoglobin of 4 g/dL, normal indices for age, a WBC count of 6.5/μL, and a platelet count of 750,000/μL. Her reticulocyte count is 0%. Coombs test is negative. Her peripheral blood smear shows no blast forms and no fragments. Red blood cell (RBC) adenosine deaminase levels are normal. A bone marrow reveals markedly decreased erythroid precursors. Which of the following is this child’s likely diagnosis?

262) On a routine-screening CBC, a 1-year-old is noted to have a microcytic anemia. A follow-up hemoglobin electrophoresis demonstrates an increased concentration of hemoglobin A2. The child is most likely to have which of the following?

263) A 2-year-old child is brought to the office by his parents for the evaluation of failure to thrive and chronic diarrhea. His diarrhea is "almost continuous", and he also has recurrent episodes of fever. He was initially quite well and was on the 60th percentile for weight; however, for the past seven months, he didn't seem to grow and failed to gain weight. Over the past three months, he fell to the 3rd percentile for weight. His parents deny any use of drugs, but they drink occasionally. His mother mentions that her former boyfriend was a heroin addict. Physical examination reveals oral thrush, generalized lymphadenopathy and eczema. What is the most likely diagnosis in this patient?

264) After being delivered following a benign gestation, a newborn infant is noted to have a platelet count of 35,000/μL, decreased fibrinogen, and elevated fibrin spilt products. On examination you note a large cutaneous hemangioma on the abdomen that is purple and firm. Which of the following anomalies might also be expected in this infant?

265) A 6-year-old girl has a low-grade fever, headache, and nasal congestion. She has a flushed face and has developed a lacy reticular rash on the trunk and extensor surface of her arms and legs. Palms and soles are spared. Her mother has been ill with a low-grade fever and some joint stiffness and pain. Which of the following is the most likely diagnosis?

266) A 3-year-old boy has had fever for 4 days. On physical examination he has bilateral cervical lymphadenopathy, injected pharynx, and dry cracked lips. A throat swab is done and the rapid strep test is negative. The child is sent home and advised to follow-up if symptoms worsen. The child is brought back 2 days later with all previous findings including a maculopapular rash, swollen hands, and conjunctivitis. Which of the following is the most likely diagnosis?

267) An 8-year-old Caucasian boy is brought to the office for the evaluation of high-grade fever, flank pain and burning micturition for the last two days. He has had two previous episodes of acute pyelonephritis. Physical examination reveals costovertebral angle tenderness. Urinalysis shows pyuria, significant bacteriuria, WBC casts, positive nitrite and esterase. The voiding cystourethrogram (VCUG) reveals vesicoureteral reflux. What is the most likely complication of this condition, if left untreated?

268) A woman comes to an emergency department because she is in labor. She has had no prenatal care. Her baby is delivered and appears to be of about 32 weeks' gestation. The newborn is very pale and shows severe, generalized edema. Cord-blood hematocrit is 22%, and cord-blood bilirubin is 7 mg/dl. Ultrasound examination demonstrates pleural effusions, ascites, cardiomegaly, and hepatomegaly. Which of the following is the most likely diagnosis?

269) A neonate is examined following a protracted breech delivery. One of the infant's arms is partially paralyzed. The affected arm is adducted and internally rotated at the shoulder, and the forearm is pronated. Which of the following is the most likely diagnosis?

270) A 2-year-old boy presents with refusal to use his right arm for 1 day. He is otherwise well. His mother states she pulled upward on his arm the previous evening to keep him from tripping down the stairs. Which of the following is the most likely diagnosis?

271) A 1-day-old infant who received silver nitrate eye drops in the delivery room is suffering from bilateral purulent conjunctival discharge. Which of the following is the most likely cause of this child’s condition?

272) A 14-year-old girl has a history of red eyes with clear discharge that she suffers from in a seasonal pattern. Together with these symptoms, she reports itching, which is her most bothersome complaint. Physical examination shows conjunctival redness, tearing, and swelling, but there is no purulent discharge. This clinical picture is most compatible with a diagnosis of which of the following conditions?

273) 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°C (101°F), 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?

274) A 14-year-old boy presents with decreased exercise tolerance. He is noted to have a grade III/VI systolic ejection murmur best heard at the left upper sternal border and a grade II/VI mid-diastolic murmur at the lower left sternal border. The first heart sound is normal. The second heart sound is widely split and fixed. A right ventricular impulse is palpated. On a chest roentgenogram, the pulmonary artery segment is enlarged, and pulmonary vascular markings are increased. An ECG shows right axis deviation. Which of the following congenital heart diseases does this boy most likely have?

275) A 7-year-old boy presents with a rash. His mother states that he was well until 3 days ago when he developed fever and malaise. The next day, the rash started as papules on the trunk, which rapidly changed to vesicles. The lesions have spread all over the body. On physical examination, he has no fever and seems well. You note numerous vesicles all over the body, some of which have crusted over. Which of the following is the most likely diagnosis?

276) A 4-year-old boy presents to the emergency department with generalized tonic-clonic seizures. On physical examination, the child is noted to be lethargic. His temperature is 37.4 C (99.3 F), blood pressure is 100/60 mm Hg, pulse is 72/min, and respirations are 16/min. His oral mucosa is moist, and there is no peripheral edema. Laboratory tests show: Blood: Sodium 120 mEq/L, Potassium 4.2 mEq/L, Chloride 96 mEq/L, Bicarbonate 20 mEq/L, Blood urea nitrogen 9.6 mg/dL, Creatinine 0.4 mg/dL, Glucose 88 mg/dL, Urine: Sodium 55 mEq/L, Potassium 16 mEq/L, Osmolality 530 mOsmol/kg. Which of the following is the most likely diagnosis?

277) A 1-month-old, previously healthy infant develops forceful projectile vomiting. No bile is seen in the vomitus. After the infant feeds, gastric peristaltic waves are visible crossing the epigastrium from left to right. Several minutes later, the projectile vomiting occurs. Which of the following is the most likely diagnosis?

278) A 5-month-old girl is brought to the office by her mother, who states that the girl had an episode following feeding during which she began to breathe deeply, became blue, and then lost consciousness. The mother states that she picked her up and held her, and the infant regained her usual color and became alert. Physical examination reveals a harsh systolic murmur. Which of the following is the most likely diagnosis?

279) Physical examination of an infant delivered to a 42-year-old, gravida 3, para 2, woman, is remarkable for slight hypotonia and a poor Moro reflex. Further examination reveals upslanting palpebral fissures, epicanthal folds, excess nuchal skin, an enlarged tongue, clinodactyly of the fifth fingers, and a single transverse palmar crease. Which of the following is the most likely diagnosis?

281) A 10-month-old infant on long-term aspirin therapy for Kawasaki disease develops sudden onset of high fever, chills, diarrhea, and irritability. A rapid swab in your office identifies influenza A, adding her to the long list of influenza patients you have seen this December. Over the next few days, she slowly improves and becomes afebrile. However, 5 days after your last encounter you hear from the hospital that she has presented to the emergency center obtunded and posturing with evidence of liver dysfunction. Which of the following statements about her current condition is correct?

282) The parents of a 7-month-old boy arrive in your office with the child and a stack of medical records for a second opinion. The boy first started having problems after his circumcision in the nursery when he had prolonged bleeding. Studies were sent at the time for hemophilia, but factor VIII and IX activity were normal. At 2 months he developed bloody diarrhea, which his doctor assumed was a milk protein allergy and changed him to soy; his parents note he still has occasional bloody diarrhea. He has seen a dermatologist several times for eczema, and he has been admitted to the hospital twice for pneumococcal bacteremia. During both admissions, the parents were told that the infant’s platelet count was low, but they have yet to attend the hematology appointment arranged for them. The child’s WBC count and differential were normal. Which of the following is the most likely diagnosis in this child?

283) A one-day-old infant with Down syndrome has developed persistent vomiting. He was delivered vaginally at 34 weeks without any complications. On examination, he appears dehydrated and slightly tachypneic. His abdomen is soft and not distended. Abdominal x-ray reveals two large distinct air bubbles, but there are no dilated bowel loops or air fluid levels. What is the most likely diagnosis of this patient?

284) A 10-year-old boy from the Connecticut coast is seen because of discomfort in his right knee. He had a large, annular, erythematous lesion on his back that disappeared 4 weeks prior to the present visit. His mother recalls pulling a small tick off his back. Which of the following is a correct statement about this child’s likely illness?

285) Two weeks ago, a 5-year-old boy developed diarrhea, which has persisted to the present time despite dietary management. His stools have been watery, pale, and frothy. He has been afebrile. Microscopic examination of his stools is likely to show which of the following?

287) A 6-year-old boy is brought to the physician for evaluation of behavior problems. His parents report he is "hyperactive all the time." They cannot get him to sit still. When he does sit, he fidgets and tries to get out of his seat. He is easily distracted and frequently changes from one activity to another. He does not seem to listen when his parents talk to him, and often forgets to do his chores. He talks excessively and often interrupts other people. His parents state that he has been like this for a few years, but they had originally assumed his behavior was normal for his age. His physical examination is unremarkable. Which of the following will be of most help in establishing the diagnosis?

288) An 8-year-old boy is brought to the office due to headaches and impaired walking. These symptoms started seven days ago, and progressed gradually. He just recently recovered from otitis media that was superimposed on an acute respiratory infection. His past medical history is significant for three episodes of otitis media and one episode of pneumonia. His temperature is 36.7C (98F), blood pressure is 100/60 mm Hg, pulse is 110/min, and respirations are 20/min. Physical examination reveals mild right-sided hemiparesis and a slightly dilated left pupil. The funduscopic examination is normal. Which of the following is the most likely diagnosis?

289) A 1-day-old male infant has bilious vomiting after every feeding. He hasn't passed any stools yet. He had no prenatal care, and was delivered vaginally at term. He weighs 3kg (6.61b), and his APGAR scores were 6 and 7 at 1 min and 5 min, respectively. On examination, the neonate is hypotonic, he has a flat facial profile, short ears with downfolding ear lobes, a single palmar crease, and a depressed fontanel. There is abdominal distention which is most prominent in the upper abdomen. His abdominal x-rays show gastric and duodenal gas distension with no air distally. What other anomaly can also be expected in this infant?

290) A 14-year-old boy is brought to the emergency room because of persistent midepigastric pain for two days. The pain is getting no better, yet it is no worse, and radiates to his back. The boy also has had fever, as well as nausea and vomiting that is worse when his temperature rises in the afternoon. On examination, his temperature is 39.2C (102.5F) and there is marked upper abdominal tenderness with guarding. Mild abdominal distention is present with no audible bowel sounds. A complete blood count reveals an elevated leukocyte count and a normal serum amylase. Which of the following is the most likely diagnosis?

291) A baby is born at 34 weeks gestation. The amniotic fluid is brown and murky. The baby has low APGAR scores and appears to be septic, with lethargy, apnea, bradycardia, and temperature instability. The mother lives on a farm and gives a history of a flu-like illness one month before delivery. Gram's stain of a smear from the mother's cervix demonstrates abundant, pleomorphic, gram-variable coccobacillary forms. Which of the following is the most likely diagnosis?

292) A 14-year-old black male comes to the office for the evaluation of pain in his right hip that started several weeks ago. The pain has gradually progressed, and now it limits his daily activities. He has sickle cell disease and was hospitalized three months ago due to a painful crisis that was successfully treated with hydration, oxygen, and analgesics. His temperature is 37.2C (99F), blood pressure is 100/70 mmHg, pulse is 80/min, and respirations are 16/min. Physical examination reveals no local tenderness, but there is restriction of abduction and internal rotation of the hip What is the most likely diagnosis?

293) A 6-year-old Caucasian male is brought to your office with a two-week history of right shoulder pain. Physical examination reveals localized swelling below the shoulder joint, and x-ray shows a single lytic lesion in the right humeral head. Laboratory analyses show mild hypercalcemia but are otherwise within normal limits. Which of the following is the most likely diagnosis?

294) An infant is born prematurely and is small for gestational age. At birth, the infant is obviously ill with jaundice, fever, hepatosplenomegaly, myocarditis, and rashes. Neurologic involvement is prominent, with hydrocephalus, intracranial calcifications, and seizures. The mother has a cat and continued to clean the cat's litter box during the pregnancy. Which of the following is the most likely causative agent?

295) A beekeeper’s previously healthy 6-month-old son develops gradual onset of lethargy, poor feeding, constipation, and generalized weakness. On taking a history, you determine that the child has recently been placed on a homemade formula consisting of evaporated milk, water, and honey. Which of the following is the most likely explanation for this symptom complex?

296) A 12-year-old girl is taken to a pediatrician complaining of a sore mouth. On questioning, the child states that she has been feeling poorly, with fatigue and weakness. She began menstruating briefly and then stopped. Physical examination is notable for focal white crusting of the oral cavity; biopsy of one of these areas later shows candidiasis, Laboratory studies show the following: Sodium 127 mEq/L, Potassium 5.3 mEq/L, Bicarbonate 24 mEq/L, Calcium 7.5 mEq/dL, Phosphorus 5.5 mg/dL, Glucose 87 mg/dL. Which of the following is the most likely diagnosis?

297) A 15-year-old girl presents with a 2-day history of pain and swelling in her left knee. She plays soccer regularly on her school team. There is no history of trauma. On physical examination, there is marked swelling and tenderness over her anterior tibial tuberosity. A radiograph of her left knee reveals irregularities of the tubercle contour and haziness of the adjacent metaphyseal border. Which of the following is the most likely explanation for her symptoms?

299) A 2-day-old male infant presents with multiple episodes of bilious vomiting over the past 24 hours. He has a prominent tongue, flat occiput and slanting eyes. His hands are short, and there are wide gaps between his first and second digits. His abdomen is soft and without any distention, guarding or rigidity. On auscultation of the chest, there is a systolic ejection murmur along the left sternal border, with a wide and fixed splitting of S2. Abdominal x- rays show air trapped in the first portion of the duodenum and stomach. What is the most likely cause of the child's symptoms?

300) A 2-year-old girl presents to the office with a dry cough and a low-grade fever. Over the last two days, she has become very irritable and difficult to feed. She has also had a runny nose. On examination, there is significant wheezing and tachycardia. Evaluation of the nasal discharge confirms the diagnosis of respiratory syncytial virus infection. In the future, which of the following does this child have a slight risk of developing?

301) A 10-month-old boy develops an upper respiratory tract infection 2 days before presentation. On the day of presentation, he has a generalized tonic-clonic seizure lasting 30 seconds. His temperature is 40.0 C (104 F), blood pressure is 90/60 mm Hg, and respirations are 22/min. He is alert and smiling. He has rhinorrhea, and his neck is supple. He has bruises below his knees. Which of the following is the most likely diagnosis?

302) A 4-month-old child presents with a 2-day history of vomiting and intermittent irritability. On examination, “currant jelly” stool is noted in the diaper, and a sausage-shaped mass is palpated in the right upper quadrant of the abdomen. Which of the following conditions is most likely to cause this?

303) A 2-hour-old full-term newborn infant is noted by the nursing staff to be having episodes of cyanosis and apnea. Per nursery protocol they place an oxygen saturation monitor on him. When they attempted to feed him, his oxygen levels drop into the 60s. When he is stimulated and cries, his oxygen levels increase into the 90s. Which of the following is the most important next step to quickly establish the diagnosis?

304) The police bring a 14-year-old boy to the clinic after he was found setting fire to the neighbor's house. He has been previously arrested and warned by the cops twice. The first time was 15 months ago for stealing his neighbor's motorcycle. The second occasion was 6 months ago for a fight with his peers on the roadside. His parents arrive and tell you that he has been behaving this way for the past 3 years, and often argues at home. He steals money from them and tries to hurt the pets. Although they have not seen him using any drugs, they suspect that his behavior could be due to drugs. What is the most likely diagnosis?

305) A 14-year-old girl presents to the emergency room for severe lower mid-abdominal pain that has been increasing over the past 12 hours. She describes it as crampy and sharp. Her last menstrual period was about 2 weeks ago. It was regular with no pain and lasted 4 to 5 days. She has had menstrual periods for nearly 2 years, and over the past 6 months she has noticed some cramping pain the first day or two of her menses. She denies sexual activity and has not had any vaginal discharge. Her bowel movements have been normal and she reports no urinary frequency, urgency, or burning with urination. Which of the following is the most likely diagnosis?

306) A 9-month-old boy is taken to the emergency room because of high fever. Breath sounds are diminished in the lungs, and a chest x-ray film shows lobar pneumonia. Probable streptococcal pneumonia is demonstrated in Gram's stain of sputum and then later confirmed by culture. The child responds to antibiotic therapy. A detailed history is taken during the admission, which reveals that this is the third episode of pneumonia in this young child; the two previous episodes occurred at 6 and 7.5 months of age. One of the mother's brothers had died of infection at age 9. Immunoglobulin studies demonstrate the following: IgG 80 mg/dL [normal 723-1685 mg/dL], IgA 60 mg/dL [normal 81-463 mg/dL], IgM 20 mg/dL [normal 48-271 mg/dL]. Studies of the lymphocyte population demonstrate normal numbers of T cells and markedly decreased B cells. Which of the following is the most likely diagnosis?

307) A newborn baby is noted to have abnormal facies with low-set ears; a small receding jaw; and widely separated eyes. At 30 hours of age, the baby develops multiple muscle spasms. Serum studies are notable for calcium of 4.5 mg/dL. Which of the following is the most likely diagnosis?

308) A 5-year-old girl is being evaluated for generalized swelling. Her blood pressure is 98/60 mm Hg. Her laboratory results show: Creatinine 0.7 mg/dl, Albumin 1.6 g/dL, Cholesterol 360 mg/dL, Triglycerides 400 mg/dL, C3 complement 120 mg/dL (normal, >80 mg/dL), Antinuclear antibody Negative, Urinalysis 1 RBC/hpf, protein 400 mg/dL. Which of the following is the most likely diagnosis?

309) A 10-year-old girl is evaluated by a pediatrician. She is already 5'8" tall and is taller than other members of her family were at this age. Her arms are disproportionately long compared with her trunk, and her sternum is outwardly displaced. Her joints are hyperextensible, particularly at the knees. Ocular examination demonstrates dislocation of one lens. Which of the following is the most likely diagnosis?

310) An 8-year-old boy is brought to the clinic by his mother, who states that he has been complaining of pain in both knees. The mother also states that he had a rash on his leg 3 weeks ago. She said it was there for almost 2 weeks and then went away. She describes the rash as reddish and circular, with a small clear area in the center. She said the rash was not itchy or painful. The child has also complained of headaches and muscle aches over the past several weeks. On questioning, the mother states that they were vacationing in Wisconsin about 1 month ago and the boy was hiking in the woods when he was bitten by a tick. Which of the following is the most likely diagnosis?

311) A male child born to a 25-year-old Caucasian mother by normal vaginal delivery at 36 weeks of gestation is found to have a small face, a small jaw, and a prominence on the back of his head. There are no skin creases on the palmar aspect of his digits. There is overlapping of his fingers bilaterally, along with rocker bottom feet and limited hip abduction. Heart murmur is present. Which of the following cardiovascular abnormality is most likely seen in this patient?

313) A 15-year-old girl is admitted to the hospital with a 6-kg weight loss, bloody diarrhea, and fever that have occurred intermittently over the previous 6 months. She reports cramping abdominal pain with bowel movements. She also reports secondary amenorrhea during this time. Stool cultures in her physician’s office have shown only normal intestinal flora. A urine pregnancy test was negative, while an erythrocyte sedimentation rate (ESR) was elevated. Her examination is significant for the lack of oral mucosal ulcerations and a normal perianal examination. Anti-Saccharomyces cerevisiae antibodies (ASCA) are negative, while anti-neutrophil cytoplasm antibodies (p-ANCA) are positive. You confirm your presumptive diagnosis with a rectal biopsy. In counseling her about her disease, which of the following statements would be true?

314) A 6-year-old boy is brought to the physician by his mother with complaints of "inattentivity." His school teacher frequently complains about him, saying that he, "cannot sit still and just does not listen." He rarely completes his classroom assignments in time. When asked to run errands at home, he appears not to listen and continues to do whatever he is engaged in. He makes poor eye contact and has limited language skills compared to his peers. He usually prefers to play by himself. Which of these is the most likely diagnosis in this case?

316) A 15-month-old Asian girl is brought to the physician's office because of persistent non-productive cough and skin rash. Other accompanying symptoms are a runny nose, sneezing and intermittent nasal obstruction. She has had these symptoms for the past four days. Her parents report that she seems to have lost interest in her usual activities and is irritable all the time. Her pulse is 130/min, temperature is 38.8C (102F), and respirations are 24/min. Her eyes are red and have a watery discharge; there is congestion that is more marked over the canthi; the inner conjunctiva has bluish white lesions on an erythematous background. Throat examination reveals erythema of the posterior pharyngeal wall and tonsillar pillars, and yellowish exudates on the tonsils. The buccal mucous membranes are red with bluish-white lesions. The face has blanching, erythematous "brick-red" maculopapular rash. No rash is present over the extremities. Cervical lymphadenopathy is noted. The lab results are as follows: Hct 46%, WBC count 3,000/mm3, Platelet 160,000/mm3, Urine Dipstick ++ for proteins. What is the most likely diagnosis?

317) A 17-year-old teenage girl presents to your office after having problems during sex with her boyfriend. She also states that she has been developing facial hair, which she has constantly been removing. She started her menstruations at the age of 13 and her cycles have always been regular. On examination she is obese but appears a little masculine and has an enlarged clitoris. Initial lab values are as follows: Serum LH 20 IU/L, Serum FSH 10 IU/L, 17 -hydroxyprogesterone 600ng/ml (Normal is 15ng/ml), Serum testosterone Normal, Serum DHEA 4.0ng/ml (Normal is 4.2ng/ml). What is the most likely diagnosis?

318) A 2-week-old male infant is brought to the office by his 28-year-old primiparous mother for the evaluation of jaundice that was noted two days ago. The infant's stool has a lighter color. He is exclusively breastfed. The pregnancy was uncomplicated, and prenatal screening tests for TORCH organisms were all negative. The infant was delivered vaginally with no complications. His temperature is 37.2 C (99F), pulse is 140/min, respirations are 50/min, and capillary refill is < 2 sec. Examination reveals jaundiced skin and mucous membranes. Abdominal palpation reveals hepatomegaly. The initial investigations show the following: Hb 18.0 g/dl, Hct 52%, Bilirubin, Total 5 mg/dl, Bilirubin, Direct 4 mg/dl, Blood type 0 + (The mother's blood type is B-), Coombs' test Negative. What is the most likely diagnosis?

320) A premature infant develops respiratory distress several hours after birth. The infant is placed in an incubator with supplemental oxygen. The physician instructs the nurse to cover the infant's eyes to minimize the chance of damage by the high oxygen tension. Which of the following is characteristic of eye damage produced by exposure to high oxygen tensions in premature infants with respiratory distress?

321) A 7-year-old boy is brought to the clinic by his mother, who states that he has been complaining of abdominal pain for 2-3 days. He has been afebrile, with no vomiting or diarrhea. His mother states she brought him to the office today because she noticed a rash on his legs that is getting worse, and he is now complaining of knee pain. On examination, there are palpable purpuric lesions on both legs and buttocks. He has pain around his ankle and knee joints with minimal swelling, and no warmth or erythema. Which of the following is the most likely diagnosis?

322) A 7-year-old boy who has had pain in his right leg for 4 months is being evaluated. The pain is worse at night and is unrelenting, but it can usually be relieved with ibuprofen. On physical examination, there is localized tenderness over the anterior aspect of the right thigh. There is also mild atrophy of the affected limb. A radiograph of the femur reveals a radiolucent nidus with surrounding reactive sclerotic bone. Which of the following is the most likely diagnosis?

323) A 2-year-old boy is brought to the emergency department due to a cough and a "whistling" sound with breathing. Two days ago, he developed rhinorrhea, fever, a hoarse cry and a progressively worsening, harsh, "barky" cough. His immunizations are up-to-date. His 6-year-old brother also has cold symptoms. His temperature is 37.5C (99.5F), pulse is 140/min, and respirations are 36/min. On examination, he is alert, in mild respiratory distress, has a dry barking cough, hoarse cry, and some clear mucoid rhinorrhea. His pharynx is slightly injected, but without enlargement or asymmetry. The lungs are clear on auscultation. Lateral neck x-rays reveal a mildly narrowed subglottic region. What is the most likely diagnosis?

324) A 2-year-old child is brought to the physician for a routine visit. He is growing and developing appropriately. He eats a variety of foods including meat, vegetables, and fruits, and drinks 3-4 glasses of whole milk each day. He is starting to put words together into short sentences. His mother has no concerns. Physical examination is unremarkable. Routine laboratory studies show the following: Hemoglobin 9.5 g/dl, RDW 14%, MCV 65 fl, Reticulocyte count 3.0%, Platelet count 212,000/mm3, Leukocyte count 6,500/mm3, TIBC 300 mcg/dl (240-450 mcg/dl), Ferritin 100 ng/ml (7 -140 ng/ml). What is the most likely cause for this child's anemia?

325) A previously healthy 5-year-old girl is brought to the physician for evaluation of night awakenings. She has woken up screaming in each of the past three nights about one hour after going to sleep. When her parents go to her room, she is crying, sweating, and looks frightened. She does not respond to her parents and does not seem fully awake. When her parents hold her, she calms down and goes back to sleep. The next morning, she does not recall the incident. She started kindergarten this week and has just begun going all day without taking a nap. On examination, she is afebrile and her vital signs are within normal limits. A complete physical examination is unremarkable. What is the most likely diagnosis?

326) A 17-year-old boy comes to medical attention because of recurrent sinusitis and pneumonia, and persistent watery diarrhea due to Giardia lamblia. His parents and a sister are in excellent health. Physical examination reveals enlarged lymph nodes in cervical, axillary and inguinal regions. A lymph node biopsy shows hyperplastic follicles with an absence of plasma cells. Laboratory investigations show: Hematocrit44%, Leukocyte count9, 800/mm3, Neutrophils55%, Lymphocytes30%, Monocytes5%, CD4 T-cell count1000 cells/mm3, Proteins, serum6.2 g/dL, Albumin5.0 g/dL, Globulin1.2 g/dL. Additional studies demonstrate severely depressed levels of serum IgG, with slightly below-normal levels of IgM and IgA. Which of the following is the most likely diagnosis?

327) An 8-year-old boy presents with a 2-day history of rash. The rash started on the head and spread downward to his trunk and extremities. He also complains of a fever, cough, and a runny nose for the past 5 days. On physical examination, his temperature is 38.2 C (100.7 F), blood pressure is 88/56 mm Hg, pulse is 76/min, and respirations are 16/min. There is a small, irregular red spot with a central gray color on his buccal mucosa. The rash on his body is erythematous and maculopapular in quality. Which of the following is the most likely diagnosis?

328) A 3-year-old child presents in clinic with marked erythema of the cheeks, with no prior symptoms. The rash soon involves the arms and has a reticular erythematous maculopapular appearance. The patient has been previously healthy and is not on any medications. He has not been exposed to any other ill individual. Which of the following is the most likely diagnosis?

329) The mother of a 6-month-old infant is concerned that her baby may be teething. You explain to her that the first teeth to erupt in most children are which of the following?

330) A 6-month-old previously health child is brought to the doctor's office because of sudden onset of lethargy, constipation, generalized weakness and poor feeding. He has been meeting all development milestones and his immunization schedule is up to date. On further questioning, his parents mention that his diet was recently advanced to a homemade formula of evaporated milk and honey. On physical examination, he has stable vital signs, clear lungs, normal skin turgor and full fontanelles. Which of the following is the most likely explanation for the patient's presentation?

331) A 15-year-old girl presents to the emergency department with the sudden onset of watery diarrhea tinged with blood. The girl was previously healthy. Her only medications are topical benzoyl peroxide and oral clindamycin for acne vulgaris. Physical examination reveals a slightly distended abdomen that is diffusely tender. Her temperature is 38.1 C (100.5 F). She has not been exposed to any uncooked meat and has not eaten any unusual foods. Which of the following is the most likely diagnosis?

332) A 22-year-old woman has just delivered a male infant at 41 weeks of gestation. Her medical history is normal and her pregnancy was uncomplicated. She is an assistant in a veterinary clinic. Examination of the infant reveals jaundice, hepatosplenomegaly, and generalized lymphadenopathy. During the examination, he suddenly begins to have tonic-clonic seizures. The CT scan reveals active inflammatory lesions, hydrocephalus and intracranial calcifications. What is the most likely diagnosis of this patient?

333) A 5-year-old girl is brought to the physician's office for a follow-up visit after recovering from an episode of acute bacterial meningitis. Five weeks ago, she developed pneumococcal meningitis, and was admitted to the hospital, where she underwent lumbar puncture, CT scan of the head, and ceftriaxone therapy. She was discharged in a stable condition. According to the mother, the child has not been performing well in school since her illness. She also noticed that the child has forgotten how to copy figures such as triangles and squares, and is unable to identify colours accurately. What is the most likely cause for the regression of milestones in this patient?

335) A 5-year-old boy is brought to the physician because of a malodorous discharge coming from his right nostril. His parents report that the child developed frequent sneezing and mucus discharge for one week. They thought it was a common cold. The child is afebrile and in apparent good health. There is no history of allergic diseases or recurrent infections. Examination reveals obstruction of the right nasal fossa with associated purulent discharge from the right nostril. Which of the following is the most likely diagnosis?

336) A 4-year-old girl is brought to your office by her mother for recent onset of fever and rash. For the past 4 days, she has had headaches, fever, and sore throat. She was apparently normal 4 days ago, and upon presentation of the symptoms, her mother thought that she was having a simple viral fever which would go away with time; however, she then developed a pale pink maculo-papular rash, first on the face and neck, and then it rapidly spread onto the trunk and limbs. On examination, the child is afebrile and doesn't appear ill, but there are few palpable suboccipital and posterior auricular lymph nodes. What is the most likely cause of this patient's condition?

338) During a regular checkup of an 8-year-old child, you note a loud first heart sound with a fixed and widely split second heart sound at the upper left sternal border that does not change with respirations. The patient is otherwise active and healthy. Which of the following heart lesions most likely explains these findings?

339) A 2-year-old child with minimal cyanosis has an S3 and S4 (a quadruple rhythm), a systolic murmur in the pulmonic area, and a middiastolic murmur along the lower left sternal border. An ECG shows right atrial hypertrophy and a ventricular block pattern in the right chest leads. Which of the following is the most likely diagnosis?

340) 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?

341) A 2-hour-old male neonate has developed worsening cyanosis over the past few minutes. The infant was vaginally delivered (assisted with forceps) at full term and weighed 4.1 kg (9 lb). The Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. Oxygen is administered by mask but does not relieve the cyanosis. Further examination reveals tachypnea, subcostal retractions, a normal first heart sound, a single and loud second heart sound (S2), and no murmur. Which of the following is the most likely cause of the infant's cyanosis?

342) A 5-year-old girl presents to the emergency department with acute onset of muscle weakness. The mother carried the girl to the examination room and states that the muscle weakness started in her daughter's legs yesterday. The weakness became worse today and progressed to the trunk and both arms. She was also complaining difficulty of breathing earlier today. She has been otherwise healthy but had a common cold about 10 days ago. On examination, her respirations are 26/min and shallow. She has profound muscle weakness in her lower extremities, and moderate weakness in her upper extremities. Her deep tendon reflexes are absent. A lumbar puncture is performed, which shows increased protein concentration but no pleocytosis. Which of the following is the most likely diagnosis?

343) A 4-year-old previously healthy but unimmunized boy presents with sudden onset of high fever, inspiratory stridor, and refusal to drink. Of the following causes of inspiratory stridor, which best fits this clinical scenario?

344) A week-old infant presents blood in his stools. He was born at home, with the father assisting in the delivery; no physician or midwife was present. He has been breast-fed and has been nursing well. On examination, you also note some blood in his nose. He is not jaundiced; a rectal examination and guaic test of the stool confirms that blood is present. His examination is otherwise normal. He is on no medications. Which of the following is the most likely diagnosis?

345) A 12-year-old American boy comes to you with the complaints of abdominal pain and dark urine. On examination he has normal vitals, icteric sclerae, and abdominal tenderness with a mass palpable in right upper quadrant. His laboratory report shows bilirubin: 6.5 mg/di, negative viral serologies and mild elevations of amylase and lipase. Ultrasonography shows a cystic extra hepatic mass and a gall bladder separated from the mass. What is the most likely diagnosis in this patient?

346) A 10-year-old boy has been having “bellyaches” for about 2 years. They occur at night as well as during the day. Occasionally, he vomits after the onset of pain. Occult blood has been found in his stool. His father also gets frequent, nonspecific stomachaches. Which of the following is the most likely diagnosis?

347) During a well-child visit, the grandmother of an 18-month-old patient is concerned because the child’s feet turn inward. She first noticed this when her grandson began to walk. It does not seem to bother the child. On examining his gait, his knees point forward and his feet turn inward. Which of the following is the most likely cause of this condition?

350) A 1-month old boy is brought to the emergency department by his mother, who states that he has been having what she describes as "projectile vomiting" for the past several days. She states that he vomits every time she feeds him, and the situation seems to be getting worse, although he does not seem to be in pain. She describes the vomitus as non-bilious, and he has had normal stools with no blood in them. On examination, the infant appears to be mildly dehydrated, his abdomen is soft, and there is a palpable, olive-sized, firm moveable mass in the right upper quadrant. Which of the following is the most likely diagnosis?

351) A pediatrician examines a 2-month-old infant who had been born at term. The pediatrician hears a continuous murmur at the upper left sternal border. The peripheral pulses in all extremities are full and show widened pulse pressure. Which of the following is the most likely diagnosis?

352) A 3-week-old infant is being evaluated for hematochezia. His mother states that the infant passed stools j that contain both blood and mucus. There were no complications during her pregnancy, and the infant has been otherwise healthy. On physical examination, his temperature is 37.1 C (98.9 F), pulse is 110/min, and respirations are 18/min. He appears well, and his fontanelle is flat and level. Abdominal examination reveals normal active bowel sounds; his abdomen is nontender to palpation and there is no mass. His diaper contains stool that has bright red blood on it with mucus. Which of the following is the most likely explanation of his hematochezia?

353) A 7-year-old boy is brought to the physician because of a persistent mucopurulent nasal discharge for 2 weeks following a common cold. The mother also reports that the child has had frequent cough during the day and occasional temperatures up to 38.0 C (100.5 F). The child does not appear critically ill, but he complains of mild pain in the maxillary region and nasal obstruction. Rhinoscopic examination reveals a rivulet of purulent fluid coming from the inferior meatus. The rest of the physical examination is normal. Which of the following is the most likely diagnosis?

354) A 9-year-old boy presents with a several-day history of progressive arm and leg weakness. He has been well except for an upper respiratory infection 2 weeks ago. The patient is alert and oriented. On repeated examination, the heart rate varies between 60 and 140 beats/min, and the blood pressure (BP) varies between 90/60 and 140/90 mmHg. Respirations are shallow, with a rate of 50/min. There is symmetric weakness of the face and all four extremities. Deep tendon reflexes are absent. Sensation is intact. Which of the following is the most likely diagnosis?

355) A previously healthy 4-year-old child pictured below presents to the emergency room (ER) with a 2-day history of a brightly erythematous rash and temperature of 40°C (104°F). The exquisitely tender, generalized rash is worse in the flexural and perioral areas. The child is admitted and over the next day develops crusting and fissuring around the eyes, mouth, and nose. The desquamation of skin shown in the photograph occurs with gentle traction. Which of the following is the most likely diagnosis?

356) A 6-year-old boy is brought to the emergency department (ED) by the paramedics due to nausea, vomiting, diarrhea and abdominal pain over the past hour. His mother found an open multivitamin supplement bottle and some pills scattered on the kitchen floor. After his admission to the ED, he starts hyperventilating and experiences hematemesis. His blood pressure is 90/60 mmHg, pulse is 130/min, respirations are 50/min and temperature is 37.2 C (99F). Abdominal plain x-ray reveals several small opacities in the stomach and duodenum. Lab results are: Hb 13.5 g/dL, Ht 42%, WBC 10,000/mm3, Platelets 300,000/mm3, Blood Glucose 118 mg/dL, Serum Na 135 mEq/L, Serum K 34 mEq/L, Chloride 102 mEq/L, Bicarbonate 16 mEq/L, BUN 16 mg/dL, Serum Creatinine 1.0 mg/dL, pH 7.30, P02: 90 mm Hg, PC02: 29 mm Hg. What is the most likely diagnosis?

357) A 3-year-old boy is brought to the office by his mother because he has been having painless passage of black stools for the past few days. Otherwise, his bowel habits are normal. He has no other medical problems. He takes no medication. His vital signs are within normal limits. The physical examination is unremarkable. What is the most likely diagnosis of this patient?

358) A 2-week-old Caucasian male presents with constipation since birth. He was born full term via a normal vaginal delivery. He did not pass meconium till his 3rd day of life, after he was given a glycerin suppository. He has since stooled every 3–4 days, only with the help of a suppository. The stools are pellet like. He has had increasing abdominal distention. On rectal examination, tone appears normal and the ampulla contains no stool. Which of the following is the most likely cause?

359) A 44 year old woman delivers a 3120 g (6 lb 14 oz) newborn male. Her pregnancy was normal except that she noted decreased fetal movement compared to her previous pregnancies. She declined an amniocentesis offered by her obstetrician. Physical examination of the newborn reveals an infant with facial features suggestive of Down syndrome. The infant then has bilious vomiting. An x-ray film showing the kidneys, ureters, and bladder (KUB) is performed, which shows a "double bubble" sign. Which of the following is the most likely cause of the abdominal signs and symptoms?

360) A 9-year-old Caucasian male complains of fever, sore throat and difficulty swallowing. Small tender lymph nodes are palpated in the cervical region. The symptoms subside quickly on penicillin therapy. Ten days later, the patient presents again with fever, skin rash and fleeting joint pain in the lower extremities. Physical examination reveals scattered urticaria and palpable lymph nodes in the cervical, axillary and inguinal regions. Which of the following is the most likely cause of this patient's current complaints?

361) A 28-month-old female has been living with her mother in a shelter for homeless women and children. She is brought to the Emergency Department in status epilepticus, which is stopped with intravenous lorazepam. She is placed on a cardiac monitor and a wide complex tachycardia is noted. The ventricular tachycardia reverts to sinus tachycardia after defibrillation is performed. Her temperature is 38.5 C (101.3 F), blood pressure is 120/80 mm Hg, pulse is 195, and respirations are 26. Physical examination reveals a lethargic, pale toddler with dilated and reactive pupils, dry mucous membranes, shallow respirations, diaphoresis and brisk deep tendon reflexes. A urine toxicology screen is most likely to detect which of the following substances?

362) A 4-year-old girl is brought to the office due to seizures that occurred 2 hours ago. This is her first episode. Her parents are also concerned because she is not able to carry on activities that children of her age are expected to do. On examination, there is a red flat lesion covering the left eye area and adjacent facial skin, which does not blanch on pressure, and which the parents say has been present since birth. Other pertinent findings are hemianopia, hemiparesis, and hemisensory disturbances. An x-ray of the skull shows tramline intra-cranial calcifications. What is the most likely diagnosis?

363) A term neonate is small for date and has a small head. Further physical examination of the infant demonstrates small eyes with short palpebral fissures, a flattened nose, and abnormal palmar creases. With which of the following maternal conditions is this presentation most likely associated?

364) A 10-day-old infant is brought to the office by her mother for the evaluation of purulent discharge from both eyes. The discharge appeared three days ago, after which the child developed a cough. On examination, the infant's eyes appear normal, except for the presence of purulent discharge. Auscultation reveals diffuse rales without wheezing. Chest radiograph shows a hyperinflated thorax. What is the most likely diagnosis?

365) A 2-month-old girl presents to her pediatrician's office for well-child care. Her mother complains of excessive tearing of the baby's left eye for the past 4 weeks. Each morning, a yellow crusty discharge is noted along the lashes of the left eye. The conjunctiva appears uninflamed. The right eye is not affected. On physical examination, the infant is otherwise well and achieving adequate weight gain on an exclusive breast milk diet. She is developmentally appropriate, including visually tracking 180 degrees. Which of the following is the most likely diagnosis?

366) A 3-week-old female infant born at 38 weeks' gestation through an uncomplicated vaginal delivery, presents to the emergency department with 2-day history of fever. The infant had been healthy since birth. Her temperature in the emergency department is 40.0 C (104.0 F). She appears to be quite lethargic. A culture taken from the infant grows group B Streptococcus (GBS) in 24 hours. Which of the following infections is most consistent with this presentation?

367) A 10-year-old boy is brought to clinic because of increasing weakness and dyspnea over the past 6 months. He has been previously healthy and is on no medications. There is no significant family history of illness. On examination, he appears pale. His hematocrit is 20%, mean corpuscular volume (MCV) is 60/mm3, and iron level is normal. Smear reveals basophilic stippling. Hemoglobin electrophoresis is consistent with the absence of one beta-globin gene. Which of the following is the most likely diagnosis?

370) A mother wishes to breast-feed her newborn infant, but is worried about medical conditions that would prohibit her from doing so. You counsel her that of her listed conditions, which of the following is a contraindication to breast-feeding?

371) A mother brings her 6-year-old daughter for evaluation because she has never been able to toilet train her. The child states that she perceives the sensation of having to void, and empties her bladder normally at normal intervals, but is nonetheless wet with urine all the time. Which of the following is the most likely diagnosis?

372) A 6-day-old girl who was born at home is being evaluated for bruising and gastrointestinal bleeding. Laboratory findings include partial thromboplastin time and prothrombin time, greater than 2 minutes; serum bilirubin, 4.7 mg/dL; alanine aminotransferase, 18 mg/dL; platelet count, 330,000/mm3; and hemoglobin, 16.3 g/dL. Which of the following is the most likely cause of her bleeding?

373) A 1-year-old African American infant is in for well-child care. He is primarily breast-fed. His parents do not give him much solid food because he has no teeth. He receives no medications or supplements. His parents are concerned about his bowed legs. On examination, you note some other bony abnormalities including frontal bossing, enlargement of the costochondral junctions, a protuberant sternum (pigeon chest), and severe bowing of the legs. You obtain x-rays to confirm your clinical diagnosis and also note a healing fracture of the left femur. Which of the following is the most likely diagnosis?

375) A 14-year-old boy presents with sudden onset of pain and swelling of his right testicle. There was no history of trauma, he is not sexually active, and denies any history of penile discharge. On examination, the scrotum is swollen and tender. The cremasteric reflex is absent. A testicular flow scan shows a “cold spot” or absent flow to the affected side. Which of the following is the most likely cause?

378) A 28-year-old Caucasian female comes to the office due to fever for the past 3 days. She also complains of pain and swelling in her right breast for the past 4 days. She exclusively breastfeeds her 3-month-old baby. On examination, she is febrile. Her right breast is engorged, red and tender, without any area of fluctuation. She wants to know if she can continue to breastfeed. Which of the following is a contraindication to breastfeeding?

379) Among the conditions that cause edema of the eyelids is orbital cellulitis. This is a serious infection that must be recognized early and treated aggressively if complications are to be avoided. Which of the following features is useful in differentiating orbital cellulitis from periorbital (preseptal) cellulitis?

380) A 30-minute-old male newborn is noted to have central cyanosis. He was born to a 16-year-old white female at 28 weeks gestation. His respirations are rapid and shallow at 70/min. His other vital signs are stable. On examination, there is audible grunting, intercostal and subcostal retractions, nasal flaring, and duskiness. On auscultation, fine rales are heard over the lung bases. Nasal oxygenation does not improve his cyanosis. A chest roentgenogram shows fine reticular granularity, predominantly in the lower lobes. Arterial blood gas analysis shows evidence of hypoxemia and metabolic acidosis. What is the most likely diagnosis of this patient?

382) A healthy 1-year-old child comes to your office for a routine checkup and for immunizations. His parents have no complaints or concerns. The next day, the CBC you performed as customary screening for anemia returns with the percentage of eosinophils on the differential to be 30%. Which of the following is the most likely explanation?

383) Two weeks after a viral syndrome, a 2-year-old child develops bruising and generalized petechiae, more prominent over the legs. No hepatosplenomegaly or lymph node enlargement is noted. The examination is otherwise unremarkable. Laboratory testing shows the patient to have a normal hemoglobin, hematocrit, and white blood cell (WBC) count and differential. The plateletcount is 15,000/μL. Which of the following is the most likely diagnosis?

384) A 30-minute-old male newborn is noted to have central cyanosis. He was born to a 16-year-old white female at 28 weeks gestation. His respirations are rapid and shallow at 70/min. His other vital signs are stable. On examination, there is audible grunting, intercostal and subcostal retractions, nasal flaring, and duskiness. On auscultation, fine rales are heard over the lung bases. Nasal oxygenation does not improve his cyanosis. A chest roentgenogram shows fine reticular granularity, predominantly in the lower lobes. Arterial blood gas analysis shows evidence of hypoxemia and metabolic acidosis. What is the most likely diagnosis of this patient?

385) Friends are considering adopting a “special needs” child from another country. The family has few details, but the information they have received so far suggests the 4-year-old child has had surgery for an endocardial cushion defect, is short for his age, and had a history of what sounds like surgically repaired duodenal atresia at birth. You are suspicious this child may have which of the following syndromes?

386) An 8-year-old boy is brought to his physician by his mother, who is worried by the child's frequent episodes of daydreaming, which have apparently resulted in a decline in school performance. The child's psychomotor development appears normal. EEG recording reveals bilateral and symmetric 3 Hz spike-and-wave discharges, which begin and end abruptly on a normal background. Which of the following is the most likely diagnosis?

387) A 1400-g infant, born at 35 weeks' gestation, is 42 cm in length and a head circumference of 28 cm. One day after birth, she becomes very irritable, tremulous, and inconsolable. Her cry is high-pitched. Her pulse is 174/min. There are no dysmorphic facial features. To which of the following substances was this newborn most likely exposed in utero?

388) A 16-year-old female presents to the emergency room with severe right- sided abdominal pain. Her last menstrual period was 2 weeks ago and felt to be normal. She displays painful difficulty in positioning herself on the examination table. Her temperature is 38.5 C (101.3 F), blood pressure is 128/75 mm Hg, pulse is 80/min, and respirations are 22/min. Examination of the throat reveals mild pharyngitis. Her abdomen is diffusely tender, especially the lower abdomen. Rectal examination reveals tenderness anteriorly on the right side. Stool guaiac is negative. A pelvic examination is performed, and there is evidence of cervical tenderness and questionable fullness in the right adnexal area. Which of the following is the most likely diagnosis?

389) The mother of one of your regular patients calls your office. She reports that her daughter has a 3-day history of subjective fever, hoarseness, and a bad barking cough. You arrange for her to be seen in your office that morning. Upon seeing this child, you would expect to find which of the following?

390) A 2 and a half-year-old child is brought to the office for the evaluation of easy bruising, nosebleeds, and decreased activity over the past week. He had an upper respiratory infection that was treated with an antibiotic 2 weeks ago. On examination, he is well-developed, seems well-nourished, anicteric, and pale. Pertinent findings include some small palpable posterior cervical lymph nodes, sinus tachycardia, a grade I/VI systolic ejection murmur, ecchymoses on his left shoulder and both lower extremities, and petechiae over his extremities and groin. There is no hepatosplenomegaly. The laboratory findings are as follows: Hemoglobin 7.9 g/dl, Hematocrit 24%, Platelet count 12, 000/mm3, WBC 3,000/mm3, Reticulocyte count 0.5%. A bone marrow biopsy reveal a markedly hypocellular marrow with decreased megakaryocytes and precursors of the erythroid and myeloid cell lines. What is the most likely diagnosis?