Autoimmune hepatitis and overlap syndromes.

Autoimmune hepatitis (AIH) is an immune-mediated, autodestructive liver disease with hepatocytes as target cells, mostly affecting young women. Primary biliary cirrhosis (PBC) is also regarded as an autoimmune liver disease with bile duct epithelia as the target cells, resulting in a continuous loss of bile ducts. Both diseases may occur simultaneously in their full manifestations in about 10% to 20% of cases, thus constituting an overlap syndrome with PBC directing the course of the disease. AIH may also occur simultaneously with primary sclerosing cholangitis (PSC), with a frequency of between 2% and 8% of patients with PSC. In most cases, AIH precedes manifestation of PSC. In children, the overlap syndrome of AIH and PSC seems to make up an entity of its own: autoimmune sclerosing cholangitis.