A Case of Unusual Polypoid Mixed Hemangioma of the Sigmoid Colon: Possibly an Angioadenomatous Polyp

Herein, we report on an unusual case of polypoid mixed hemangioma of the sigmoid colon. An 85-year-old woman who underwent colonoscopic examination was found to have a smooth, red polypoid tumor, 6mm in diameter, in the sigmoid colon. The polyp was resected endoscopically. Microscopically, the polyp contained two pathologic components: (i) adenomatous proliferative glands as the epithelial component; and (ii) mixed hemangioma as the mesenchymal component. On the basis of these findings, a pathological diagnosis of angioadenomatous polyp was made. Although seven previous cases of polypoid hemangioma located in the submucosa have been reported in the literature, the present case is the first in which the hemangioma is localized only in the mucosa. The mixed hemangioma may be the pathogen stimulating the adenomatous proliferation of the glands.