Practical approach to the pathologic diagnosis of gastritis.

CONTEXT Most types of gastritis can be diagnosed on hematoxylin-eosin stains. The most common type of chronic gastritis is Helicobacter pylori gastritis. Reactive or chemical gastropathy, which is often associated with nonsteroidal anti-inflammatory drug use or bile reflux, is common in most practices. The diagnosis of atrophic gastritis can be challenging if few biopsy samples are available and if the location of the biopsies in the stomach is not known, such as when random biopsies are sampled in one jar. If the biopsy site is not known, immunohistochemical stains, such as a combination of synaptophysin and gastrin, are useful in establishing the biopsy location. OBJECTIVE To demonstrate a practical approach to achieving a pathologic diagnosis of gastritis by evaluating a limited number of features in mucosal biopsies. DATA SOURCE In this article, we present several representative gastric biopsy cases from a gastrointestinal pathology practice to demonstrate the practical application of basic histopathologic methods for the diagnosis of gastritis. CONCLUSIONS Limited ancillary tests are usually required for a diagnosis of gastritis. In some cases, special stains, such as acid-fast stains, and immunohistochemical stains, such as for H pylori and viruses, can be useful. Helicobacter pylori immunohistochemical stains can particularly contribute (1) when moderate to severe, chronic gastritis or active gastritis is present but no Helicobacter organisms are identified upon hematoxylin-eosin stain; (2) when extensive intestinal metaplasia is present; and (3) in follow-up biopsies, after antibiotic treatment for H pylori.