Carcinoid-related angiomatous polyposis simulating Crohn disease

Polyposis associated with ileal carcinoid tumors is a rarely described pathologic mucosal transformation that may simulate inflammatory or neoplastic polyps. We describe a case with innumerable sessile polyps and groups of large filiform-like polyps of the terminal ileum associated with submucosal carcinoid tumors and a large mesenteric carcinoid tumor mass. The clinical, radiographic, and endoscopic presentation of the polyposis, together with the presence of multiple small bowel stenotic lesions, simulated Crohn disease. We propose the descriptive terminology angiomatous polyposis to describe the striking microscopic vascular proliferation that characterizes these polyps. The distribution of these lesions, with the most profuse polyposis in the immediate proximity of the carcinoid nests, and the immunohistochemical demonstration of growth factor substances, such as transforming growth factor alpha within neoplastic cells and adjacent polyps, suggest a tumor factor-mediated stromal proliferation.