Transanal total mesorectal excision for primary rectovaginal carcinosarcoma: A case report and literature review.

We report a case of rectovaginal septum carcinosarcoma successfully treated with surgical excision via transanal total mesorectal excision following platinum-based neoadjuvant chemotherapy. A 48-year-old woman presented with a 3-week defecation pain preceding the visit. Pelvic imaging showed an 8-cm sized lesion in the lower rectovaginal septum. Transvaginal biopsy and immunohistochemical analysis were performed. After three courses of carboplatin-paclitaxel-bevacizumab therapy, the mass reduced by half. Subsequently, laparoscopic excision with transanal total mesorectal excision, and radical hysterectomy were performed. The anus was preserved, and dysuria improved within a month. The final histopathological diagnosis was carcinosarcoma of the rectovaginal septum from an uncertain origin, presumably endometriotic or mesonephric. Twelve months following surgery, solitary liver metastasis was confirmed; however, there was no evidence of local recurrence. Total mesorectal excision following platinum-based neoadjuvant chemotherapy may be an ideal treatment for gynecological malignancies in the rectovaginal septum, especially for large tumors localized deep into the pelvis.