Submucosal tunneling endoscopic resection with bidirectional full-thickness resection of gastrointestinal stromal tumor: a case report.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Whereas surgical resection remains the criterion standard for high-risk lesions, minimally invasive endoscopic techniques are emerging as viable alternatives. Exophytic subepithelial lesions pose unique challenges for standard endoscopic techniques, including incomplete resection and potential injury to adjacent structures. This case report presents a novel bidirectional full-thickness resection (FTR) technique for resecting an exophytic gastric GIST in a 63-year-old man. The procedure involved submucosal tunneling, peritoneal entry, and circumferential FTR from both the peritoneal and the tunnel sides, ensuring complete removal of the lesion. Mucosal incision closure was achieved by use of an endoscopic suturing system, with no postprocedural adverse events. The diagnosis of GIST was confirmed histopathologically. Twenty-one months after the procedure, no recurrence was observed on imaging. Bidirectional FTR potentially enhances visualization, improves resection completeness, and minimizes procedural risks, making it a promising technique for managing exophytic subepithelial lesions.