Hepatobiliary pathology.

PURPOSE OF REVIEW: Recent studies pertaining to the histopathology of the liver and biliary tract are reviewed. RECENT FINDINGS: Several studies are reviewed which describe the histologic features and clinical behavior of 'plasma cell hepatitis' in the posttransplant setting. Cytokeratin 7, EMA, and CD68 were found to be useful immunohistochemical stains in fibrolamellar hepatocellular carcinoma and may aid in the distinction between this variant and classic hepatocellular carcinoma. Arginase-1, another immunohistochemical stain, was found to have improved sensitivity over HepPar-1 in the diagnosis of classic hepatocellular carcinoma. Metabolic syndrome is common in children with nonalcoholic fatty liver disease and may be an indicator of more severe disease activity and fibrosis. Histologic features were described that may aid in the distinction between the steroid-responsive IgG4-associated cholangitis and the steroid-nonresponsive primary sclerosing cholangitis. In addition, immunohistochemical stains for IgM and IgG may be helpful in distinguishing between autoimmune liver diseases, with primary biliary cirrhosis and its antimitochondrial-negative variant, autoimmune cholangitis, being the two autoimmune liver diseases with a predominance of IgM-positive plasma cells. SUMMARY: Several informative studies pertaining to hepatobiliary pathology were published this year, with topics including posttransplant plasma cell hepatitis, familial hemophagocytic lymphohistiocytosis, pediatric nonalcoholic fatty liver disease, and the use of immunohistochemical stains specific for various immunoglobulin subtypes.