Gastritis, defined by the inflammation or irritation of the stomach lining or gastric mucosa, manifests in several distinct forms: acute, chronic, reactive, and a specific subtype known as autoimmune metaplastic atrophic gastritis.

Acute gastritis presents as a sudden inflammation triggered by various stressors to the stomach lining, such as exposure to corrosive agents, local irritants like aspirin and other NSAIDs, alcohol consumption, radiation therapy, physical trauma, severe burns, sepsis, alkaline-bile reflux, or infections like enteroviruses. This condition often results from reduced gastric mucus secretion, disruption of the mucosal barrier, or decreased blood flow to the mucosa, leading to symptoms that can be managed by removing the irritant and supporting the stomach's healing.

In contrast, chronic gastritis develops gradually and may persist for several months to years if left untreated. It is commonly caused by infection with Helicobacter pylori, autoimmune disorders that target the stomach lining, age-related changes, or continuous exposure to bile reflux. Managing this form of gastritis involves addressing the underlying cause, such as eradicating H. pylori or managing autoimmune responses.

Reactive gastritis, or gastropathy, is characterized by histological mucosal lesions resulting from prolonged exposure to certain medications, alcohol, radiation therapy, or bile reflux, especially following gastric surgery. Though usually asymptomatic, it is detectable through endoscopic examination.

Another noteworthy form is autoimmune metaplastic atrophic gastritis, a condition stemming from an immune response against stomach parietal cells. This leads to low chloride levels, intrinsic factor deficiency, cobalamin malabsorption, and pernicious anemia, all of which significantly increase the risk of stomach cancer.

Understanding the distinct types of gastritis is essential for effective diagnosis and management, guiding tailored treatments that range from dietary adjustments and medications to more specific interventions aimed at eradicating infections or managing autoimmune conditions, thereby preventing complications such as ulcers, bleeding, and, in severe cases, cancer.