Saline-tunneling endoscopic submucosal dissection for residual rectal lesion at anastomotic staple line

Endoscopic submucosal dissection (ESD) in surgically altered colorectal anatomy is challenging because of postsurgical fibrosis and the presence of staples. We report a case of a combined saline immersion and tunneling ESD ("saline-tunneling" ESD) for a lesion at a stapled rectal anastomosis.

A 67-year-old man with T3N1M0 rectal cancer underwent neoadjuvant chemoradiotherapy in 2019 followed by proctosigmoidectomy in 2020. A postoperative colonoscopy detected a residual lesion, but the patient was lost to follow-up until 2023. At that time, ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography scan showed a non-fluorodeoxyglucose-avid soft-tissue mass just above the anastomosis without nodal or distant metastases. Colonoscopy revealed a 3.5-cm granular, mixed-nodular laterally spreading tumor spanning the anastomotic staple line. Near-focus magnifying endoscopy narrow-band imaging with indigo carmine showed Kudo V_i and Japan Narrow-Band Imaging Expert Team 2B features consistent with advanced neoplasia. We performed saline-tunneling ESD under continuous saline immersion to enhance visualization, stability, and margin acquisition.

En bloc resection of the lesion was achieved. Histopathology confirmed a tubulovillous adenoma with high-grade dysplasia and negative margins.

This case demonstrates the successful integration of submucosal tunneling and saline immersion techniques at a stapled rectal anastomosis. The novel saline-tunneling ESD approach may offer a safe, effective alternative to repeat surgery for fibrotic, anatomically constrained colorectal lesions.