A case of adult autoimmune hepatitis with histological features of giant cell hepatitis.

Giant cell hepatitis is rare in adult patients. This form of hepatitis shows fast progression to cirrhosis. A 65-year-old woman was admitted to our hospital with jaundice. She was negative for hepatitis virus markers and positive for antinuclear antibodies. We diagnosed her as autoimmune hepatitis. Liver biopsy findings revealed typical features of interface hepatitis and giant cell hepatitis. Giant cells were positive for keratin 8/18, but not for keratin 19, keratin 7 or Ki-67. These results suggest that giant cell formation is associated with the fusion of matured hepatocytes rather than the active proliferation of immature cells.