This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Bowel Disease, Subject name: Pathology
Backwash ileitis is seen in: 
Select and explain. 
A. Crohn's disease, B. Ulcerative colitis, C. Colonic carcinoma, D. Ileal polyp
B: Ulcerative colitis
Answer: B: Ulcerative colitis 
Explanation: BACKWASH ILEITIS: - Extends contiguously backward from cecum without skip regions. - It is seen in ulcerative colitis where eventhough small intestine is normal, mild mucosal inflammation of distal ileum is seen.