Multiple microcarcinoids arising in chronic ulcerative colitis.

A 50-year-old man who had chronic ulcerative colitis with dysplasia and two synchronous carcinomas had a total colectomy. Microscopic examination of the resected specimen revealed multiple microcarcinoids that were all smaller than 2 mm in diameter and not visible with gross examination. Histologic examination revealed that they were similar to microcarcinoids of the stomach encountered in patients with pernicious anemia. In this patient, however, there was no associated endocrine cell hyperplasia in the overlying mucosa, and the carcinoids may have arisen from dysplastic stem cells in the colonic crypts.