[A case of endometrioid carcinoma arising from endometriosis of the rectum].

A very rare case with rectal endometriosis heterotopic transformed into carcinoma is reported. A 44-year-old female patient underwent colostomy due to ileus. Postoperative examinations revealed submucosal tumors all around the rectum. Low anterior resection and the closure of the colostomy were performed. Thickening in the muscular layer and serosa were observed in the resected specimen, but the mucosal surface was maintained. Histopathological observation revealed glands of the endometrium and connective fibers with glandular adenocarcinoma in the periphery. Transformation of the benign endometrial tissues into carcinoma and squamous metaplasia were observed. A diagnosis of endometrial carcinoma in the rectum was made.