Gastric adenocarcinoma of fundic gland type (chief cell predominant type) with unique endoscopic appearance curatively treated by endoscopic submucosal resection

Gastric adenocarcinoma of fundic gland type [chief cell predominant type; (GA-FD-CCP)] is a rare gastric cancer variant arising from non-atrophic mucosa without Helicobacter pylori infection in the upper third portion of the stomach. GA-FD-CCP originates deep in the mucosal layer; hence, endoscopic lesion detection is often difficult at an early stage because of a minimal change in the mucosal surface. Here we present a 66-year-old man with an early stage of GA-FD-CCP showing characteristic endoscopic features. Esophagogastroduodenoscopy demonstrated a flat, slightly reddish area with black pigment dispersion and irregular micro-surface structure at the gastric fornix. The tumor was resected by endoscopic submucosal dissection and was pathologically diagnosed as GA-FD-CCP. Prussian blue staining revealed that the black pigment was a hemosiderin deposition. We reported a rare case of successfully treated GA-FD-CCP with black pigmentation that aided in early lesion detection.