Underwater endoscopic mucosal resection of an incompletely resected superficial non-ampullary duodenal epithelial neoplasm using the loop-and-let-go technique: A case report.

Rationale Endoscopic resection of superficial non-ampullary duodenal epithelial neoplasm (SNADEN) is a challenging procedure owing to the high recurrence rate and considerable incidence rate of adverse events. Patient concerns SNADEN accidentally found during a medical examination in a 56-year-old man. Diagnosis The patient was diagnosed as having a 20-mm-sized flat elevated SNADEN at the superior duodenal angle. Interventions First, we tried to perform conventional EMR (CEMR). However, the submucosal injection interrupted the endoscopic view and did not provide enough space for CEMR because of its angulated location. Therefore, we chose to perform endoscopic resection using the "loop-and-let-go" technique. Follow-up duodenoscopy after 2 days revealed post CEMR ulcer with suspicious remnant lesion. Underwater endoscopic mucosal resection (UEMR) was successfully performed 3 months after the first session of endoscopic resection. Outcomes Complete endoscopic en bloc resection and histological complete resection were achieved with UEMR. Follow-up duodenoscopy revealed no recurrence. Lessons Step-by-step endoscopic treatment with UEMR following loop-and-let-go technique may be a good strategy for SNADEN over 20-mm in diameter.