Endometrioid adenocarcinoma arising from endometriosis of the rectum

Abstract

A 56-year-old female developed melena. On colonoscopy, a submucosal-like tumor was found in the rectum. The tumor appeared to have originated from the uterus or the ovary due to the presence of atypical clear cells in the biopsy specimen. However, the preoperative diagnosis was difficult to make since the patient had a hysterectomy and a bilateral oophorectomy previously. With a provisional diagnosis of a submucosal tumor of the rectum, a low anterior resection of the rectum, along with a regional lymph node dissection, was done. The tumor was located mainly in the submucosal layer, ; ulceration in the rectal mucosa was present. On histology, the tumor consisted of clear cell adenocarcinoma ; endometriosis was noted around the tumor located in the rectal wall. There fore, a diagnosis of endometrioid adenocarcinoma was made. This lesion was considered to have arisen from ectopic endometriosis located in the rectum. Eighteen months postoperatively the patient's condition remains good and there are no signs of tumor recurrence. We report a very rare case of endometrioid adenocarcinoma arising from ectopic endometriosis of the rectum.