Gastric submucosal cysts, carcinomas, and atypical hyperplasia have been observed in the superficial mucosa of 12 stomachs. It is thought that gastritis may give rise to these heterotopic glands, that the development of heterotopic cysts in the submucosa may make the surface mucosa prone to erosion, and that repeated erosion and regeneration may cause carcinoma or atypical hyperplasia.