Endometrial adenocarcinoma arising from endometriosis of the rectosigmoid colon

Only 21.3% of cases of malignant transformation of endometriosis occur at extragonadal pelvic sites. Forty cases of endometriosis-associated intestinal tumors are reported in the literature. Of these, 17 cases are primary adenocarcinomas arising in the rectosigmoid colon. In 8 of the 17 case reports the patients were using unopposed estrogen replacement therapy.

The patient had previously undergone a total abdominal hysterectomy and bilateral salpingo-oophorectomy for deeply infiltrating rectovaginal endometriosis, and was using estrogen replacement therapy. She presented with rectal bleeding 12 years later, and a polyp was detected arising from the sigmoid colon. A biopsy detected malignant transformation of endometriosis to adenocarcinoma.

This is the ninth case of a patient with this condition reported in the literature.