Atrophic gastritis UMLS:C0017154 Atrophy of the gastric mucosa is the endpoint of chronic processes, such as chronic gastritis associated with Helicobacter pylori (H. pylori) infection, other unidentified environmental factors, and autoimmunity directed against gastric glandular cells. Chronic atrophic gastritis HP:0002582 SNOMEDCT_US:84568007 Atrophic gastritis (AG) is a histopathological entity that is characterized by chronic inflammation of the gastric mucosa with loss of gastric glandular cells and replacement by intestinal-type epithelium, pyloric-type glands, and fibrous tissue. Gastritis