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An unusual cause of rectal hemorrhage in a patient with well-controlled ulcerative colitis.

Question: A 27-year-old man with a 3-year history of ulcerative pancolitis presented to the emergency department with 1 large liquid bloody bowel movement and abdominal pain. His ulcerative colitis (UC) had been well-controlled on 6-mercaptopurine and balsalazide. Before his presentation, he had been having 1 formed bowel movement per day and no abdominal pain. He also denied fever and malaise, both of which he had experienced during previous UC flares. He was evaluated with a colonoscopy, showing maroon blood in the proximal colon, numerous small polypoid lesions throughout the colon (Figure A), and a large pedunculated mass with an adherent clot in the cecum (Figure B). Removal of the clot revealed a small area of ulceration on the mass (Figure C). The mass was biopsied and the area of ulceration was injected with 5 mL of 1:10,000 epinephrine. No further bleeding was noted. What is the diagnosis? See the GASTROENTEROLOGY web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.