Paper II
Question
Differences between Crohn disease and Ulcerative colitis
Answer
| Feature | Crohn disease | Ulcerative colitis |
|---|---|---|
| Anatomical location | Any part of GI tract, mouth to anus (most commonly terminal ileum) | Limited to colon and rectum |
| Distribution | Skip lesions (segmental, discontinuous) | Continuous, starting from rectum and extending proximally |
| Depth of involvement | Transmural (full-thickness) | Limited to mucosa and submucosa |
| Gross appearance | Cobblestone mucosa, deep linear/serpiginous ulcers, creeping fat, strictures | Diffuse mucosal erythema/ulceration, pseudopolyps |
| Granulomas | Present (non-caseating, in ~35-50% of cases) | Absent |
| Fistulas/strictures | Common (due to transmural inflammation) | Rare |
| Rectal involvement | Often spared | Almost always involved |
| Malignancy risk | Increased (lower than UC) | Increased (higher, related to extent/duration of colitis) |
| Extraintestinal manifestations | Similar spectrum (arthritis, uveitis, erythema nodosum, primary sclerosing cholangitis) — seen in both | Similar spectrum, including a stronger association with primary sclerosing cholangitis |
| Smoking | Risk factor (worsens disease) | Protective (paradoxically, though not a treatment) |