[Laparoscopic Resection of an Ectopic Endometriosis-Associated Carcinoma Arising in the Rectum-A Case Report].

A woman in her seventies presented with mucous hematochezia. Colonoscopy revealed a poorly differentiated adenocarcinoma in the upper rectum. Immunohistochemical staining showed CK7 positivity and CK20/CDX2 negativity, findings atypical for primary colorectal carcinoma. Contrast-enhanced CT and pelvic MRI demonstrated circumferential thickening of the rectal wall with an adjacent multilocular cystic lesion, raising suspicion of an endometriosis-associated intestinal tumor (EAIT). Laparoscopic low anterior resection with D3 lymphadenectomy was performed along with total hysterectomy and bilateral salpingo-oophorectomy. Histopathological examination revealed submucosal adenocarcinoma with CD10-positive endometrial stromal cells surrounding the tumor, consistent with EAIT. The patient received 6 courses of adjuvant chemotherapy with docetaxel and carboplatin. No recurrence has been detected during 3 years and 9 months of postoperative follow-up. This case may provide valuable insight into the diagnosis and multidisciplinary management of this uncommon disease.