Endoscopic intraperitoneal subcyrrosal dissection. Better view, safer operation. The authors declare no conflicts of interest. Gastric submucosal tumor originated from deep layers of the gastric wall can be resected by EFTR or STER. However, the lesions with predominantly extraluminal growth pattern are usually in a tangent position, and the endoscopic view from gastric lumen is inherently poor for the reason that only very small part of the tumor can be seen from inside. In addition, the highly movable tumor with limited endoscopic exposure increases the difficulty in the in-block resection as well as safe hemostasis. Herein, we try to develop a modified method called endoscopic intraperitoneal subcyrrosal dissection for the removal of gastric SMT with predominantly extraluminal growth pattern. The first case was a 37-year-old gentleman. EUS and CT scan showed that the tumor originated from the deep muscularis papillae with predominantly extraluminal growth. EGD showed an SMT in the greater curvature of the gastric body. EISD was performed. First, a 1.5-centimeter gastric mucosal incision was created about 4 centimeters proximal to the lesion after submucosal injection. Subsequently, a short submucosal tunnel was created between the submucosa and the muscularis papillae. The gastric muscularis papillae was then intentionally perforated about 3 centimeters away from the lesion. The 3-centimeter distance provided critical working space and better visualization of the lesion. After locating the lesion on the serosa of the gastric wall from the abdominal cavity, After locating the lesion on the serosa of the gastric wall from the abdominal cavity, the tumor was carefully dissected from the serosa and the underlying muscularis papillae without interruption of the tumor capsule. Subserosal injection was performed when necessary to create working space or to identify the layer. Caution should be taken to avoid damage of the integrity of the mucosa during this dissection. When the lesion was fully resected, it was removed from the gastric cavity. Finally, after careful hemostasis, the mucosal entrance was closed with endoclips. The operation took 70 minutes. The pathology result was stromal tumor. The endoscopy and CT follow-up three months later showed several clips remaining, and follow-up at six months later showed complete healing. The second case was a 2.5 cm SMT in the anterior of the greater curvature of the gastric body, also with extra-luminal growth, which originated from the muscularis propria. Again, EISD was performed with the following steps as described in the previous case. Mucosal incision, Semicosal tunneling, Intentional perforation, Perforation, Locating the lesion, Intraperitoneal subacerosal dissection, tumor removal, hemostasis, and closure of the mucosal incision. The operating time was 65 minutes. The pathology result was also stromal tumor. Follow-up CT after two months showed satisfactory healing with no residual tumor. There are several advantages of this new technique. First, the maintaining of mucosa intact at the lesion site and the short tunnel at the mucosal incision site could reduce the infection and other complications due to perforation. Second, the tunnel makes closure of the wound much easier than the otherwise unsmooth full thickness defect. More importantly, for most SMTs with a predominantly extraluminal growth pattern, we only have a tangent view from the gastric cavity and the highly movable tumors challenge the angle of the scope and increases the risk of pulmonary residual and capsule damage. On the contrary, when dissecting from the serosal site in the abdominal cavity, the distance between the perforation and the lesion enables the operator to have a direct and full exposure and helps to sterilize the tumor. In conclusion, EISD is a feasible and safe attempt for the removal of gastric SMT with predominantly extraluminal growth pattern. Large-scale prospective studies are needed to evaluate its safety and efficacy.

endoscopic intraperitoneal subserosal dissection

gastric submucosal tumors

extraluminal growth patterns

EISD

mucosa integrity