Sexually transmitted infectious colitis vs inflammatory bowel disease: distinguishing features from a case-controlled study.

Objectives: Sexually transmitted infectious (STI) colitis often raises concern for inflammatory bowel disease (IBD). In this study, we compare histologic features of IBD with STI colitis caused by syphilis and lymphogranuloma venereum.

Methods: The STI colitis group included 10 unique colorectal biopsy specimens in patients with clinically confirmed syphilis and/or lymphogranuloma venereum. The STI biopsy specimens were compared with patients matched for age, sex, and site with Crohn disease (n = 10) or ulcerative colitis (n = 10). All IBD controls had an established history of IBD (up to 276 months of follow-up, mean follow-up = 102 months).

Results: Discriminating features (P < .05) of STI colitis included its exclusive identification in human immunodeficiency virus-positive men who have sex with men, anal pain, and anal discharge. STI colitis contained the triad of (1) minimal active chronic crypt centric damage, (2) a lack of mucosal eosinophilia, and (3) submucosal plasma cells, endothelial swelling, and perivascular plasma cells. Nondiscriminating features (P > .05) included rectal bleeding, endoscopic appearance, skip lesions, ulcerations, aphthoid lesions, granulomata, foreign body giant cells, neural hyperplasia, fibrosis, and lymphoid aggregates.

Conclusions: While STI colitis shares many overlapping features with IBD, histologic and clinical discriminating features may be helpful when confronted with that differential diagnosis.