[Gastric Inverted Hyperplastic Polyp Removed Using Endoscopic Submucosal Dissection].

Gastric subepithelial tumors (SETs) are usually asymptomatic and are often detected incidentally during screening endoscopy. A gastric inverted hyperplastic polyp (IHP) is characterized by downward growth of hyperplastic mucosa into the submucosal layer. Owing to these characteristics, a gastric IHP is frequently misdiagnosed as a SET. Gastric IHPs are asymptomatic in most cases and are discovered incidentally. Notably, IHPs may be accompanied by an adenocarcinoma or anemia owing to chronic bleeding associated with this lesion; therefore, endoscopic submucosal dissection is recommended for complete excision of IHPs measuring > 2 cm. We report a case of gastric IHP that was diagnosed during screening endoscopy in an asymptomatic patient. We observed a whitish purulent exudate expressed from the SET, and endoscopic ultrasonography revealed a SET originating from the muscularis mucosa. Endoscopic submucosal dissection was performed to remove the SET, and final histopathological findings revealed a gastric IHP. This case report highlights that IHPs should be suspected in patients with a SET associated with whitish exudates.