Paper II
Question
Compare and contrast four important microscopic features of Crohn’s disease and Ulcerative Colitis
Answer
Four important microscopic features distinguishing Crohn’s disease from Ulcerative Colitis:
| Feature | Crohn’s Disease | Ulcerative Colitis |
|---|---|---|
| Depth of inflammation | Transmural (full-thickness) | Limited to mucosa and submucosa |
| Granulomas | Non-caseating granulomas present (in ~40–60% of cases) | Absent |
| Crypt architecture | Focal/patchy crypt distortion, may be relatively preserved in less involved areas | Diffuse crypt architectural distortion with crypt abscesses throughout involved mucosa |
| Distribution/ulceration pattern | Discontinuous (“skip lesions”); linear/serpiginous fissuring ulcers producing a “cobblestone” mucosal appearance | Continuous, diffuse mucosal involvement; broad-based superficial ulcers |
(Additional distinguishing features: Crohn’s shows transmural lymphoid aggregates and submucosal fibrosis/thickening (“creeping fat” grossly); UC is limited to the colon/rectum with continuous proximal extension from the rectum.)