A case of endometrioid carcinoma of the rectum arising from rectal endometriosis treated by laparoscopic surgery

症例報告 腹腔鏡で治療しえた直腸子宮内膜症から発生した類内膜癌の1例 キーワード: Endometrioid carcinoma, Endometriosis-associated intestinal tumor (EAIT), Laparoscopic surgery 2020 年 36 巻 2 号 p. 246-252 詳細 抄録 The frequency of malignant transformation in endometriosis is rare; it is estimated to be less than 1%. Malignant transformation mainly occurs in the ovary and rarely in the extragonadal sites. Endometriosis-associated intestinal tumors (EAITs) represent the malignant transformation of gastrointestinal endometriosis; the prevalence of EAITs is 0.77% in Japan. Here, we present a case of endometrioid carcinoma of the rectum arising from rectal endometriosis that was treated by laparoscopic surgery. A 68-year-old woman presented with no symptoms but had a pelvic mass and was referred to our hospital. She had no history of endometriosis and hormone replacement therapy. Tissue biopsy revealed a poorly-differentiated adenocarcinoma, and the immunohistochemical studies showed cytokeratin7+, cytokeratin20-, and estrogen receptor+. Therefore, the tumor was suspected to be of gynecological origin and not primary colon origin. She underwent laparoscopic total hysterectomy, bilateral salpingo-oophorectomy, and low anterior resection with D3 lymphadenectomy. There were no malignant findings in the uterus and ovaries. The tumor was located adjacent to the rectal wall; endometrial glands and stroma were present adjacent to the tumor. We diagnosed her with endometrioid carcinoma arising from endometriosis of the rectum. No metastatic lymph nodes were identified pathologically. The patient received adjuvant chemotherapy postoperatively and has been disease-free for 18 months since the surgery. The basic treatment for EAITs is surgery, and we could treat her through laparoscopy. Laparoscopy, a minimally invasive surgery, is another treatment option for EAITs. © 2020 日本産科婦人科内視鏡学会