Successful Sphincter-Preserving Resection of a Giant Rectal Schwannoma Using Transanal Total Mesorectal Excision: A Case Report

INTRODUCTION: Rectal schwannomas are rare, accounting for less than 10% of all gastrointestinal schwannomas. When they are large and located in the lower rectum, achieving complete resection while preserving sphincter function can be technically challenging. Transanal total mesorectal excision (TaTME) provides an enhanced view of the deep pelvis and facilitates precise dissection around the anorectal junction. We report a case of a giant rectal schwannoma that was successfully resected with anal preservation using TaTME. CASE PRESENTATION: A 30-year-old woman was referred with an 11-cm rectal tumor in the pelvis identified during pregnancy. MRI revealed a well-circumscribed mass surrounding the lower rectum, in broad contact with the uterus, vagina, and anal sphincter. Endoscopic ultrasound-guided fine-needle aspiration demonstrated a benign schwannoma. Considering the patient's strong desire for sphincter preservation, laparoscopic intersphincteric resection assisted by TaTME was performed. The operative time was 317 minutes with minimal blood loss (35 mL). The tumor was completely resected with negative margins, and no diverting stoma was required. Pathology confirmed a plexiform schwannoma without malignancy. The postoperative course was uneventful, and the patient was discharged on POD 12. At 3 months postoperatively, anal function was satisfactory, with a Low Anterior Resection Syndrome score of 14 indicating only minor symptoms. CONCLUSIONS: TaTME is a useful surgical strategy for large rectal tumors in which conventional laparoscopic approaches provide limited visualization. This approach enabled complete resection with preservation of anal sphincter function in a patient with a giant rectal schwannoma.