Paper II
Question
Differentiate between ulcerative colitis and crohn’s disease
Answer
| Feature | Ulcerative Colitis | Crohn’s Disease |
|---|---|---|
| Location | Colon and rectum only, always involves rectum, extends proximally in continuity | Anywhere from mouth to anus, most often terminal ileum and colon |
| Distribution | Continuous, diffuse involvement | Skip lesions (discontinuous, “skip areas”) |
| Depth of inflammation | Mucosa and submucosa only | Transmural (full thickness) |
| Gross appearance | Broad-based ulcers, pseudopolyps, loss of haustra (“lead-pipe” colon) | Linear/serpiginous “bear-claw” ulcers, “cobblestone” mucosa, thickened wall, creeping fat |
| Microscopy | Crypt abscesses, crypt architectural distortion, no granulomas | Non-caseating granulomas (in ~40–60%), transmural lymphoid aggregates |
| Strictures/fistulae | Rare | Common (due to transmural inflammation and fibrosis) |
| Smoking | Protective/may improve | Worsens disease |
| Malignancy risk | Increased risk of colorectal carcinoma (related to extent/duration) | Increased risk of carcinoma, but somewhat lower than UC for a given extent |
| Extraintestinal manifestations | Both share primary sclerosing cholangitis, arthritis, uveitis, erythema nodosum (PSC more strongly linked to UC) | Same list; also more commonly associated with perianal disease |
| Surgery | Curative (total colectomy removes disease) | Not curative (disease can recur elsewhere) |