Organ System Pathology USMLE Step 1 Practice Question
A full-term male newborn presents with abdominal distention, bilious emesis, and failure to pass meconium by 48 hours of life. Vital signs show HR 145/min, RR 42/min, BP 65/40 mmHg, and temperature 37.2°C. Abdominal X-ray reveals a transition zone with proximal bowel dilation. Rectal examination causes explosive stool release. Notably, there is no intestinal perforation. Rectal suction biopsy is most likely to show which of the following histologic finding?
Answer choices
- AAbsence of ganglion cells in the submucosal and myenteric plexusesCorrect answer
- BEctopic pancreatic tissue in an ileal diverticulum
- CHypertrophy of the circular muscle layer of the pylorus
- DTransmural granulomatous inflammation
- EMucosal pseudopolyps limited to the rectum
- FIncreased acetylcholinesterase staining in nerve fibers of the lamina propria and muscularis mucosae
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