Submucosal tunneling endoscopic resection with bidirectional full-thickness resection of gastrointestinal stromal tumor. Gastrointestinal stromal tumor, or GIST, is the most common neoplastic subepithelial lesion of the GI tract. Surgical resection is the primary treatment approach for localized GIST. Endoscopic resection techniques to remove subepithelial lesions include submucosal tunneling endoscopic resection, full-thickness resection, and endoscopic submucosal dissection. Challenges of standard endoscopic resection techniques for subepithelial exophytic lesions include incomplete lesion removal, risk of injury to surrounding structures and vessels, and risk of hemorrhage. A 63-year-old male with a history of abdominal pain who had multiple unremarkable upper endoscopies most recently underwent abdominal pelvic CT with contrast. The CT scan showed a homogeneous 1.7 cm partially exophytic nodule along the distal greater curvature of the stomach. It was suspicious for GIST based on the imaging. The MRI also showed a smoothly marginated 1.7 cm oval submucosal nodule along the distal greater curvature of the stomach. The decision to proceed with endoscopic resection was driven by the patient's preference for intervention over surveillance. Due to subepithelial and exophytic nature of the lesion, submucosal tunneling endoscopic resection combined with full thickness resection was planned to be performed. A mucosal bleb was created by submucosal injection proximal to the lesion. A mucosal incision was made with an electrocuttery knife. The submucosal fibers were dissected. The submucosal tunnel was extended until the subepithelial lesion was fully exposed. The lesion was noted to be primarily exophytic. Initially to observe the exophytic part of the lesion, full thickness myotomy in the submucosal tunnel proximal to the lesion was performed, and the gastroscope was advanced into the peritoneum. Gastric wall vessels around the lesion were coagulated. Circumferential full thickness resection of the lesion was performed. The full thickness resection 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 the endoscopic suturing system. As shown in the video, the lesion was marked with soft coagulation to guide the submucosal tunneling. Following the submucosal injection, mucosal incision, and submucosal tunneling, the subepithelial lesion was revealed. Submucosal injection followed by submucosal dissection around the lesion was performed to fully expose the lesion. In order to identify the exophytic component, cuttery was applied to the muscle in the submucosal tunnel proximal to the lesion and a blunt passage was used to create entry into the peritoneum. A varice needle was placed in the right lower quadrant for management of normal peritoneum during the procedure. The peak inspiratory pressure was closely monitored throughout the procedure and maintained below 20 cmH2O. The exophytic component of the mass was identified and gastric wall vessels around the lesion were coagulated. After completion of prophylactic coagulation of gastric wall vessels at the lesion, the valve of the varus needle was closed to maintain nomoperitoneum and separation of the surrounding visceral organs from the gastric wall. Circumferential full thickness reduction of the lesion was performed. The access to the peritoneum not only added an extra dimension to visualization but also made the dissection less blind and facilitated the procedure, decreasing the risk of injury to the surrounding structures and blood vessels. Prior to completing the resection, the gastroscope was exchanged for a double-channel gastroscope which was advanced to the lesion within the tunnel. The lesion was completely removed while ensuring a secure hold on it. Subsequently, the lesion was retrieved. The mucosal incision site was entirely closed using an endoscopic suturing system and a total of two sutures. The valve on the varus needle was opened again for complete abdominal decompression. Patient was hospitalized overnight and kept NPO until upper GI series result. He received PPI as well as IV antibiotics while NPO followed by oral antibiotics. Post-procedure upper GI series showed no evidence of leak, and the histology report confirmed yeast. Bidirectional FDR in exophytic subepithelial lesions offers a safe and minimally invasive option and potentially reduces the risk of incomplete resection. It facilitates dissection from the peritoneal side and adds another dimension of visualization and reduces the risk of injury to surrounding structures and blood vessels. In conclusion, bidirectional FDR is feasible for subepithelial tumor resection, especially those with exophytic components. It appears to offer complete resection of subepithelial tumor without the associated risk of injury to the surrounding structures or hemorrhage.

submucosal tunneling endoscopic resection

gastrointestinal stromal tumors

full-thickness resection

endoscopic procedure

subepithelial tumor removal