A Case of Clear Cell Adenocarcinoma Arising in the Endometriosis of the Rectum Treated by Laparoscopic Surgery

Yu Okazawa, Rina Takahashi, Kousuke Mizukoshi, Kazuhiro Takehara, Shun Ishiyama, Kiichi Sugimoto, Makoto Takahashi, Yutaka Kojima, Michitoshi Goto, Atsushi Okuzawa, Yuichi Tomiki, Kazuhiro Sakamoto

Juntendo University Fucalty of Medicine

We report a very rare case of clear cell adenocarcinoma arising from endometriosis of the rectum. An 83-year-old woman was admitted for the chief complaint of hematochezia in June 2012. There was no previous illness except for hypertension.

Colonoscopy revealed a tumor around about half of the rectal circumference, located 13 cm from the anal verge. Biopsy of the tumor revealed a well differentiated adenocarcinoma. However, it was histrologically atypical of a carcinoma of the colon and rectum. Barium enema showed a 45-mm-long polypoid lesion, accompanied with a trapezoidal change, located at the anterior wall of the rectum. Abdominal computed tomography and magnetic resonance imaging examination showed an enhanced wall thickness of the rectum, with no suspicion of surrounding invasion.

Preoperative serum tumor-marker, CEA, CA19-9, anti-p53 antibody, and CA125 level were within normal limits. On laparoscopy, no metastasis of the liver or peritoneum was seen; however, the rectal tumor partially adhered to the uterus. During surgery, no tumor was identified at the radial margin of the uterus. Laparoscopic low anterior resection and partial resection of the uterus were performed in July 2012.

Histopathological examination revealed an adenocarcinoma, similar to clear cell carcinoma of the ovary, invading the subserosa and no metastasis of lymph nodes. Immunohistochemical staining showed diffuse weakly positive membrane staining of tumor cells with CA125. There was also diffuse strong positivity for cytokeratin 7, but no staining for cytokeratin 20, which was in the stained adjacent normal colonic mucosa. Finally, a diagnosis of endometrioid adenocarcinoma was made.

Malignant transformation in endometriosis was first described by Sampson in 1925, who recommended that three criteria be met for a definitive diagnosis, namely: (1) there should be histological evidence of endometriosis in close proximity to the tumor; (2) no other primary site of malignancy should be identified; and (3) the histological appearance of the tumor should be compatible with an origin in endometriosis. In our case, all criteria were satisfied.

There is a report that the rate of malignant transformation in endometriosis is 0.7 – 1.0%, with 80% occurring in the ovary. Endometrioid adenocarcinoma arising from ectopic endometriosis is very rare, and was first described by Marx in 1949. Including our case, 7 cases have been reported in Japan. Surgery is the first choice of treatment, but there is also a report that hormonal treatment and systemic chemotherapy are available. Careful observation is required because the prognosis following malignant transformations in endometriosis is poor.

We report a very rare case of endometrioid adenocarcinoma arising from ectopic endometriosis of the rectum treated by laparoscopic surgery.

Session: Poster Presentation

Program Number: P060

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