Gastric duplication cyst removed by endoscopic submucosal dissection.

Duplication cysts are uncommon congenital malformations that may occur anywhere throughout the alimentary tract. The stomach is an extremely rare site of occurrence. Here, we report a case of gastric duplication cyst initially presenting with a gastric submucosal tumor. A 28-year-old man complained of dyspepsia lasting 1 year and upper endoscopy revealed an ellipsoid submucosal tumor at the greater curvature of the antrum. We intended to use the injection-and-cut technique: however, after saline injection, the lesion was dented and impossible to grasp with a snare. Therefore, we decided to perform endoscopic submucosal dissection and removed the tumor without complication. Histopathology revealed a 0.6×0.6 cm-sized duplication cyst, and there has been no recurrence in 2 years.