Unusual gastric polyp showing submucosal proliferation of glands: case report and literature review

We report an unusual pedunculated polyp in the stomach in a 41-year-old woman. She was hospitalized because of epigastric discomfort. Endoscopy revealed a polyp with a long stalk in the fundus of the stomach. The polypectomyzed polyp measured 23 x 18 x 9 mm and was characterized by submucosal proliferation of glands and cystic dilatation. The surface of the polyp was covered with gastric mucosa of fundic or pyloric gland type. The glandular structures consisted of various types of lining cells, including pyloric or mucous-neck cell type, surface mucous (foveolar) cell type, parietal-like cells, and somatostatin-positive cells. The submucosal glandular or cystic elements were connected with the overlying gastric mucosa through a defect of the muscularis mucosa, suggesting that this polyp may have been formed by the heterotopic inverted downgrowth of mucous glands into the submucosa. We discuss the histogenesis of this rare polyp and present a review of the literature.