Chronic gastritis is a chronic inflammation of the stomach, a type of gastritis. It may be caused by Helicobacter pylori infection (Helicobacter pylori gastritis), an autoimmune mechanism (autoimmune gastritis; AIG), chemical injury, other mechanisms, or it may be idiopathic.
The most common cause of chemical injury in the stomach is nonsteroidal antiinflammatory drugs, though bile reflux is another cause that is especially seen in patients who have had a partial gastrectomy. Similar changes are seen secondary to alcohol ingestion, which is another chemically injurious substance.
There are a number of other types of gastritis including granulomatous gastritis caused by Crohn's disease, sarcoidosis or tuberculosis. Menetrier's disease is a form of gastropathy with greatly enlarged mucosal folds.