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.