A 35-year-old Indian woman presents with a 2-year history of bloody diarrhoea, mucus in stools, and lower abdominal cramps. Colonoscopy reveals continuous mucosal inflammation starting from the rectum and extending to the left colon. Histological examination of the colonic biopsy shows the feature marked **A** in the diagram. Which of the following best describes the pathological significance of this finding in the context of ulcerative colitis?
A. Granulomatous inflammation with epithelioid histiocytes, confirming the diagnosis of inflammatory bowel disease
B. Infiltration of lymphocytes and plasma cells in the lamina propria, representing chronic adaptive immune response
C. Collections of neutrophils within crypt lumina, indicating acute mucosal inflammation characteristic of ulcerative colitis
D. Transmural inflammation extending through all layers of the bowel wall, distinguishing ulcerative colitis from other forms of colitis
Explanation
Why "Collections of neutrophils within crypt lumina, indicating acute mucosal inflammation characteristic of ulcerative colitis" is right
The structure marked A is a crypt abscess — a hallmark histological feature of ulcerative colitis. Crypt abscesses are defined as collections of neutrophils within the lumen of colonic crypts, representing acute neutrophilic infiltration in response to mucosal injury. This finding is pathognomonic for UC and reflects the acute inflammatory phase of the disease. According to Robbins & Cotran, crypt abscesses are one of the six key histological hallmarks of UC, along with cryptitis, crypt distortion, basal lymphoplasmacytosis, goblet cell depletion, and pseudopolyps in chronic disease.
Why each distractor is wrong
Infiltration of lymphocytes and plasma cells in the lamina propria, representing chronic adaptive immune response: While basal lymphoplasmacytosis (structure C) is indeed present in UC, this describes a different histological feature (marked C in the diagram, not A). Lymphoplasmacytosis occurs between the crypt base and muscularis mucosae, whereas crypt abscesses are specifically neutrophil collections within crypts.
Transmural inflammation extending through all layers of the bowel wall, distinguishing ulcerative colitis from other forms of colitis: This describes Crohn disease, not ulcerative colitis. UC is characterised by mucosal and submucosal inflammation only, whereas Crohn disease shows transmural inflammation. The presence of transmural disease would argue against UC.
Granulomatous inflammation with epithelioid histiocytes, confirming the diagnosis of inflammatory bowel disease: Granulomas are explicitly ABSENT in ulcerative colitis. Their presence suggests Crohn disease instead. Granulomas are not a feature of UC histology.
High-YieldNEET PG
Crypt abscesses (neutrophils in crypt lumina) are the hallmark acute finding in UC; their absence or presence of granulomas should prompt consideration of Crohn disease.
Robbins & Cotran Pathologic Basis of Disease, 10th ed
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