[Autoimmune hepatitis and autoimmune cholangitis]

Autoimmune liver diseases encompass autoimmune hepatitis, primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) as lesions of the biliary tract. The term autoimmune cholangitis has not been generally accepted, so it remains an entitiy waiting for precise definition. AIH is a chronic progressive necroinflammatory liver disease mostly occuring in female individuals and leading to ultimate autodestruction of the liver if not treated. Histopathology of the liver reflects the gerneral understanding of the underlying immune especially self reactive CD4 + T-helper cells mediated mechanisms in destruction of liver cells displaying a typical but by no means pathognomonic histopathological pattern. Since there are no specific and generally valid tests the diagnosis should be confirmed by a scoring system including histopathology. Variants of autoimmune hepatitis cover seronegative cases, acute onset autoimmune hepatitis and autoimmune hepatitis with centrilobular necrosis. Differential diagnosis of autoimmune hepatitis includes drug induced chronic hepatitis that may mimick autoimmune hepatitis by clinical course and serology. Histopathology may give helpful hints for the correct diagnosis. Autoimmune lesions of the biliary tract are PBC in the first line. The target antigen of the autoimmune response has been identified, natural history of the diseases is well known and histopathology is pathognomonic in about a third of the cases. In clinical practice liver biopsy is taken to exclude other etiologies when AMA is present in the serum, staging the disease at first diagnosis and to establish diagnosis in cases of AMA negativity. The autoimmune nature of PSC has been discussed in the literature ever since the first description and the answer in not settled yet. Histopathology is relevant for the diagnosis in excluding other etiologies and confirming the diagnosis of small duct PSC. The term autoimmune cholangitis has been used to designate AMA-negative PBC, however, based on research experience and the clinical data it should be reserved to the overlap syndrome of AIH and PSC in children that seem to make up a disease entitiy of its own.