A 70-year-old Japanese man with a submucosal gastric mass that continued to increase in size underwent endoscopic submucosal dissection using the pocket creation method. Histologically, some epithelial cell nuclei were enlarged, but there was little atypia overall and no sign of malignancy, suggesting a diagnosis of submucosal heterotopic gastric gland (SHGG). SHGG that enlarges over time has been associated with gastric cancer, but a preoperative diagnosis is difficult. This case was very valuable, as it enabled us to follow the course of SHGG over a period of about nine years, from the onset to enlargement.
Keywords: endoscopic submucosal dissection; pocket creation method; submucosal heterotopic gastric gland; submucosal tumor.