Stoma-free precision sphincter-preserving surgery with J-pouch for metastatic low rectal neuroendocrine tumor.

R0 resection and maximal preservation of anal function without a permanent stoma remains challenging in patients with a rectal neuroendocrine neoplasm (R-NEN) within 5 cm of the anal verge and lymph node metastasis in the iliac vascular region. A 22-year-old man presented with a 1-year history of paroxysmal palpitations and cold sweats. Colonoscopy revealed a 2-cm mass with well-defined margins located 5 cm from the anal verge. Biopsy revealed a neuroendocrine tumor. Endoscopic submucosal dissection and pathology revealed a G2 R-NEN with negative margins but vascular invasion. Enhanced MRI and whole-body PET/CT identified metastases in the left iliac and right common iliac vascular regions with presacral lymph node involvement. The patient underwent precision functional sphincter-preserving surgery combined with colonic J-pouch anal anastomosis without a stoma. The patient started oral short-peptide enteral nutrition on postoperative day (POD)3 and advanced to a liquid diet on POD8 and a semi-liquid diet on POD10. He was discharged on POD12, with no anastomotic leakage observed within 30 days. Histopathology confirmed stage T1bN1M0 disease. At the 7-month follow-up, the patient reported satisfactory anal, urinary, and sexual function and had maximal global health and quality of life scores. The favorable outcomes in this young case of G2 R-NEN suggests that precision functional sphincter-preserving surgery integrated with a colonic J-pouch may be a clinical reference for achieving oncological radicality while optimizing physiological outcomes. This strategy offers an alternative to traditional radical surgery for young patients and those with high functional demands. However, its safety, functional durability, and oncological efficacy require confirmation in larger, prospective multicenter studies with longer follow‑up.