Delta viral hepatitis. Histopathology and course.

Delta viral hepatitis is important to recognize on hepatic tissue as its presence may explain severe or fulminant acute viral hepatitis, "relapse" of acute viral hepatitis, fulminant acute viral hepatitis in a chronic hepatitis B carrier, exacerbation of previously silent chronic active hepatitis, and the change in course of persistent viral hepatitis to progressive chronic active hepatitis. Histologic clues to support delta infection are primarily the severity of hepatocellular necrosis and inflammatory response. Specific immunologic procedures are required for diagnosis and include serum testing (antigen, antibody for IgG and IgM types) and antigen detection in tissue by immunofluorescence or immunoperoxidase staining. This agent is currently important as a cause of hepatitis in IV drug users, male homosexual patients, and recipients of blood products. Further studies are needed with careful accurate classification of hepatitis B patients in order to recognize the pattern of spread, severity, and outcome of delta hepatitis in other populations.