A hidden challenge: 2 novel endoscopic techniques to resect gastric exophytic subepithelial lesions.

Background and Aims: Subepithelial gastric tumors originating from the muscularis propria, such as GI stromal tumors (GISTs), are challenging to remove endoscopically because of their deep location. Full-thickness resection (FTR) requires advanced endoscopic techniques to achieve complete and safe tumor removal. Methods: Two novel natural orifice translumenal endoscopic surgery (NOTES) techniques were applied for endoscopic resection of GISTs. In the first, a bidirectional FTR was performed using both luminal and peritoneal sides for resection. In the second, dissection was done from the peritoneal side while preserving mucosal integrity. Results: A 2-cm GIST was resected en bloc using bidirectional FTR. A second incidental 1.5-cm lesion discovered intraoperatively upon peritoneal exploration was resected using a serosal approach with mucosal preservation, requiring no closure. Full-thickness closure of the first resection site was achieved endoscopically with suturing systems. Conclusions: These 2 NOTES-based techniques allowed complete resection of exophytic GISTs without the need for surgical access. Bidirectional FTR permitted controlled dissection from both peritoneal and luminal sides, whereas the serosal approach preserved the mucosa and eliminated the need for closure. Together, these methods expand the endoscopic options for managing deep gastric subepithelial tumors.