IBD IBD Pathophysiology 1 — Questions and Answers
Question 1: Which cytokine is predominantly elevated in Crohn's disease and drives the Th1 immune response?
- TNF-α and IFN-γ (Correct answer)
- IL-4 and IL-13
- IL-5 and IL-9
- TGF-β and IL-10
Correct answer: TNF-α and IFN-γ
Crohn's disease is characterized by a Th1-driven immune response with elevated TNF-α and IFN-γ promoting granulomatous inflammation.
Question 2: In ulcerative colitis, inflammation characteristically begins at which anatomical location?
- Terminal ileum
- Ascending colon
- Rectum (Correct answer)
- Sigmoid colon
Correct answer: Rectum
Ulcerative colitis almost always begins at the rectum and extends proximally in a continuous, uninterrupted pattern.
Question 3: Which layer of the intestinal wall is primarily involved in ulcerative colitis inflammation?
- Serosa and adventitia
- Muscularis propria only
- Mucosa and submucosa (Correct answer)
- All layers (transmural)
Correct answer: Mucosa and submucosa
UC inflammation is limited to the mucosa and submucosa, whereas Crohn's disease causes transmural (full-thickness) inflammation.
Question 4: Non-caseating granulomas on biopsy are pathognomonic of which IBD condition?
- Ulcerative colitis
- Indeterminate colitis
- Crohn's disease (Correct answer)
- Microscopic colitis
Correct answer: Crohn's disease
Non-caseating granulomas are a hallmark histological finding specific to Crohn's disease and are absent in ulcerative colitis.
Question 5: Which genetic mutation is most strongly associated with Crohn's disease susceptibility?
- NOD2/CARD15 (Correct answer)
- HLA-B27
- MEFV
- CFTR
Correct answer: NOD2/CARD15
Mutations in the NOD2/CARD15 gene, which encodes an intracellular pattern recognition receptor, are the most replicated genetic risk factor for Crohn's disease.
Question 6: The 'skip lesion' pattern of bowel involvement is a hallmark feature of which IBD type?
- Ulcerative colitis
- Crohn's disease (Correct answer)
- Ischemic colitis
- Infectious colitis
Correct answer: Crohn's disease
Skip lesions — areas of diseased bowel separated by segments of normal mucosa — are characteristic of Crohn's disease, unlike the continuous pattern of UC.
IBD IBD Pathophysiology 1
Which cytokine is predominantly elevated in Crohn's disease and drives the Th1 immune response?