SUBMUCOSAL TUNNELING ENDOSCOPIC RESECTION (STER) WITH BIDIRECTIONAL FULL-THICKNESS RESECTION (FTR) OF GASTROINTESTINAL STROMAL TUMOR (GIST)

Background: Gastrointestinal Stromal Tumor (GIST) is the most prevalent neoplastic subepithelial lesion in the GI tract. Surgical resection, the traditional treatment for localized GIST, is preferred in exophytic lesions due to challenges associated with standard endoscopic techniques, including incomplete lesion removal, risk of injury to surrounding structures, and potential hemorrhage. Case Presentation: A 63-year-old male who underwent multiple unremarkable upper endoscopies due to abdominal pain, most recently underwent abdominopelvic CT with contrast, which revealed a homogenous 1.7 x 1.2 cm partially exophytic nodule along the distal greater curvature of the stomach, suspicious for GIST. The decision to proceed with endoscopic resection was driven by the patient's preference for intervention over surveillance. Endoscopic Methods: The subepithelial lesion found in distal gastric body, along the greater curvature was first marked with soft coagulation to guide the submucosal dissection (Video 1). The mucosal incision was created along the greater curvature in the mid gastric body, proximal to the lesion. A submucosal injection, followed by mucosal incision was performed, and the submucosal fibers were dissected. The submucosal tunnel was further extended until the subepithelial lesion was fully exposed. The lesion was noted to be primarily exophytic, and the decision was made to proceed with full thickness resection (FTR). Proximal to the lesion in the submucosal tunnel, cautery was applied to the muscle, and a blunt passage was used to create entry into the peritoneum. The exophytic component of the mass was identified from the peritoneal side, and gastric wall vessels around the lesion were identified and coagulated. A second full thickness myotomy adjacent to the lesion was created, and circumferential FTR of the lesion was then performed. Before completing the resection, the gastroscope was exchanged for a double channel gastroscope. The lesion was securely grasped by forceps, and an endoscopic knife was passed through the second channel and FTR of the lesion was completed while maintaining firm grasp of the lesion. The lesion was then successfully retrieved. Complete closure of the mucosal incision site was achieved using an endoscopic suturing system. Conclusion: Bidirectional FTR offers a safe and minimally invasive approach for managing exophytic subepithelial lesions. This technique not only reduces the risk of incomplete resection but also enhances dissection, provides an additional dimension of visualization, and minimizes the risk of injury to surrounding structures and blood vessels.