Histology USMLE Step 1 Practice Question
A 32-year-old man with a 6-year history of ulcerative colitis presents with bloody diarrhea, tenesmus, and left lower quadrant abdominal pain. Vital signs: HR 94/min, BP 119/75 mmHg, temperature 37.1°C. Laboratory studies show hemoglobin 10.2 g/dL and elevated inflammatory markers. Colonoscopy demonstrates continuous ulceration and loss of normal mucosal pattern limited to the colon. Sigmoid colon biopsy reveals dense infiltration by lymphocytes and plasma cells with crypt distortion and intact muscularis propria. Which histologic finding best explains the endoscopic appearance of mucosal ulceration and loss of normal architecture?
Answer choices
- AAcute transmural inflammation extending through the muscularis propria
- BAcute inflammation limited to the epithelial layer with surface erosions
- CChronic inflammation of the lamina propria with loss of mucosal integrityCorrect answer
- DFibrosis and stricture formation involving the submucosa
- EThinning of the muscularis mucosae with herniation of mucosa
- FSerular involvement with perforation risk
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