Endoscopic Submucosal Dissection for Gastric-phenotype Adenoma on the Surface of Gastric Gastrointestinal Stromal Tumor.

We herein report a rare case of a gastric adenoma overlying a gastrointestinal stromal tumor (GIST) that was removed by endoscopic submucosal dissection (ESD). A 78-year-old woman was referred to our hospital. Esophagogastroduodenoscopy revealed an elevated lesion of 15 mm in diameter overlying a submucosal mass in the gastric cardia. ESD was performed for the epithelial neoplasm, and biopsy specimens were obtained directly from the exposed surface of the submucosal tumor. The epithelial tumor was a tubular adenoma with focal severe atypia and a gastric phenotype. Biopsy specimens revealed a GIST, which was resected by laparoscopic intragastric surgery afterward.