Intestinal-type gastric adenocarcinoma without Helicobacter pylori infection successfully treated with endoscopic submucosal dissection

A 67-year-old woman was admitted to our hospital for further examination and for treatment of gastric neoplasia located on the posterior wall of the antrum of the stomach, as revealed by screening esophagogastroduodenoscopy. The patient had no history of Helicobacter pylori (H. pylori) eradication. Her serum H. pylori antibody and urea breath test results were negative, histopathological findings revealed no H. pylori bacteria, and endoscopic findings revealed no chronic gastritis. We performed endoscopic submucosal dissection (ESD). Histological examination of the resected tissues revealed the tumor to be composed of a well-differentiated tubular adenocarcinoma with a tubular-type adenoma confined to the mucosa. This adenocarcinoma exhibited immunohistochemical expression of CD10, MUC2, and Cdx2, but not MUC5AC or MUC6. This is an extremely rare case of H. pylori infection-negative, intestinal-type, differentiated gastric adenocarcinoma revealed by detailed immunohistochemical examination that was treated with ESD. The patient has had no recurrence of adenocarcinoma after ESD.