Endometrioid adenocarcinoma of the rectovaginal septum with invasion of the rectum: a case report and review of literature

Background Malignant transformation of endometriosis in the rectovaginal septum is rare and usually misdiagnosed as a colorectal or gynecological tumor. We report a rare case of primary endometrioid adenocarcinoma of the rectovaginal septum with invasion of the rectum. Case presentation A 57-year-old overweight woman presented with vaginal bleeding and self-reported left lower abdominal pain during the previous 2 weeks. Preoperative imaging showed a large pelvic mass with invasion of the rectum, suggestive of a gynecologic malignancy. Multiple endoscopic biopsies and immunohistochemical analyses of specimens was performed. The patient received joint gynecological-surgical laparotomy, and there were no intra- or postoperative complications. The histopathological diagnosis was rectovaginal endometrioid adenocarcinoma with rectum infiltration. The patient received adjuvant chemotherapy and achieved good treatment response, with no early complications. At 12 months after surgery, there was no evidence of recurrence. Conclusions A high index of clinical suspicion is required for the diagnosis of endometrioid adenocarcinoma in the rectovaginal septum. Surgery combined with additional chemotherapy or radiotherapy seems to be a standard treatment, and hormonal therapy is optional. The efficacies of other therapies, including targeted medication and immunotherapy, are unknown.