Multiple adenocarcinomas and premalignant changes in "backwash" ileitis.

In a patient with long-staning ulcerative colitis and "backwash" ileitis, multiple carcinomas developed in the colon and ileum. In both locations premalignant mucosal changes of the basal cell proliferation type were seen adjacent to and remote from sites of carcinoma. Although the frequency of such premalignant and malignant changes in "backwash" ileitis is unknown, their concurrence in this case suggests that ulcerative colitis involving the terminal ileum increases the risk of small bowel carcinoma.