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Free notes, MCQs, tables & flowcharts for USMLE Step 3 Pediatrics
A girl is evaluated at 30 months of age. Her head circumference has crossed from the 50th percentile at birth to below the 3rd percentile at 12 months and has remained there. Her weight and length are tracking along the 25th percentile. She was born at term without perinatal complications. She was noted to have normal social smiling and babbling at 6 months, but her mother reports a period of apparent developmental regression between 12 and 18 months during which she lost purposeful hand use and began repetitive hand-wringing movements. Which genetic mechanism most likely accounts for this clinical picture?
ATrinucleotide CAG repeat expansion on chromosome 4
BLoss-of-function mutation in the MECP2 gene on the X chromosome
CDeletion of the maternal 15q11-q13 region
DTrisomy of chromosome 21 due to nondisjunction
EDeletion of chromosome 22q11.2
A 4-year-old boy is brought to the physician by his parents because of fever and mild abdominal pain for 7 days. His parents report that he developed a rash 2 days ago. He has had no diarrhea or vomiting. Four weeks ago, he returned from a camping trip to Colorado with his family. His immunization records are unavailable. His temperature is 39.4°C (102.9°F), pulse is 111/min, respirations are 27/min, and blood pressure is 96/65 mm Hg. Examination shows bilateral conjunctival injections and fissures on his lower lips. The pharynx is erythematous. There is tender cervical lymphadenopathy. The hands and feet appear edematous. A macular morbilliform rash is present over the trunk. Bilateral knee joints are swollen and tender; range of motion is limited by pain. Which of the following is the most appropriate treatment for this patient's condition?
ASupportive treatment only
BIntravenous immunoglobulin
COral ibuprofen
DOral penicillin
EOral doxycycline
A 4-year-old boy is brought to a pediatrician by his parents with a history of fever for the last 5 days and irritability, decreased appetite, vomiting, and swelling of the hands and feet for the last 3 days. The patient’s mother mentions that he has been taking antibiotics and antipyretics prescribed by another physician for the last 3 days, but there has been no improvement His temperature is 39.4°C (103.0°F), pulse is 128/min, respiratory rate is 24/min, and blood pressure is 96/64 mm Hg. On physical examination, there is significant edema of the hands and feet bilaterally. There is a 2.5 cm diameter freely moveable, nontender cervical lymph node is palpable on the right side. A strawberry tongue and perianal erythema are noted. Conjunctival injection is present bilaterally. Laboratory findings reveal mild anemia and a leukocytosis with a left-shift. Erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) are increased. If not treated appropriately, this patient is at increased risk of developing which of the following complications?
ALower gastrointestinal hemorrhage
BCoronary artery ectasia
CAcute renal failure
DPulmonary embolism
EAcute disseminated encephalomyelitis (ADEM)
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