Chronic gastritis

Chronic gastritis is a histopathologic entity characterized by chronic inflammation of the stomach mucosa. Gastritides can be classified on the basis of the underlying cause (eg, Helicobacter pylori, bile reflux, nonsteroidal anti-inflammatory drugs [NSAIDs], autoimmunity, or allergic response) and the histopathologic pattern, which may suggest the cause and the likely clinical course (eg, H pylori –associated multifocal atrophic gastritis).

Other classifications are based on the endoscopic appearance of the gastric mucosa (eg, varioliform gastritis). Although some gastropathies, such as those associated with NSAID intake, exhibit minimal inflammation, these entities are discussed in this article because they are frequently included in the differential diagnosis of chronic gastritis.

Chemical or reactive gastritis is caused by injury to the gastric mucosa resulting from reflux of bile and pancreatic secretions into the stomach, but it can also be caused by exogenous substances, including NSAIDs, acetylsalicylic acid, chemotherapeutic agents, and alcohol. These chemicals cause epithelial damage, erosions, and ulcers that are followed by regenerative hyperplasia detectable as foveolar hyperplasia, and damage to capillaries, with mucosal edema, hemorrhage, and increased smooth muscle in the lamina propria.

Because inflammation is minimal or lacking in these chemical-caused lesions, gastropathy or chemical gastropathy is a more appropriate description than chemical or reactive gastritis, as proposed by the updated Sydney classification of gastritis. It is important to keep in mind that mixed forms of gastropathy and other types of gastritis, especially H pylori gastritis, may coexist.

No single classification provides an entirely satisfactory description of all types of gastritis. However, an etiologic classification at least provides a direct target toward which therapy can be directed, and for this reason, such a classification is used in this article. In many instances, chronic gastritis is a relatively minor manifestation of diseases that predominantly manifest in other organs or manifest systemically (eg, gastritis in individuals who are immunosuppressed).

H pylori gastritis is a primary infection of the stomach and is the most frequent cause of chronic gastritis. Cases of histologically documented chronic gastritis are diagnosed as chronic gastritis of undetermined etiology or gastritis of undetermined type when none of the findings reflect any of the described patterns of gastritis and a specific cause cannot be identified.