The Pathology of Autoimmune Hepatitis

Abstract

Autoimmune hepatitis (AIH) is characterized by prominent portal, periportal and lobular plasma cells with interface hepatitis. Scoring systems have been developed to objectively categorize histologic features as compatible with or atypical for autoimmune hepatitis depending on the presence of prominent plasma cells, interface hepatitis, emperipolesis, and hepatocyte rosette formation, although newer studies have called into question the specificity of some of these findings. In the acute setting, the liver biopsy may demonstrate striking portal, periportal, and lobular lymphoplasmacytic inflammation, with interface activity or apoptotic hepatocytes at the limiting plate (historically termed ‘piecemeal necrosis’). Chronic AIH may show features of more advanced liver fibrosis and less dense inflammatory infiltrate. Immune-mediated drug injury may be difficult to distinguish from de novo autoimmune hepatitis but clinical and histologic correlation can usually, at a minimum, lead to a favored diagnosis.