Autoimmune hepatitis (AIH) is a progressive inflammatory disorder of unknown etiology, characterized histologically by interface hepatitis, serologically by the presence of non-organ specific autoantibodies, biochemically by elevated aminotransferases and serum IgG, and clinically by response to immunosuppressive treatment in the absence of other known causes of liver disease .
The spectrum of chronic inflammatory diseases of the liver extends from acute hepatitis to chronic hepatitis and finally to cirrhosis. In 1950, Waldenstrom described a form of chronic hepatitis occurring predominantly in young women with arthralgias, myalgia, hepatosplenomegaly, amenorrhea, skin rashes, fluctuating course, and invariably fatal outcome . The term “lupoid” hepatitis was coined after the detection of anti-nuclear antibodies (ANAs), the then positive test for lupus erythematosus in some of these individuals. The identification of anti-smooth muscle antibody (ASMA) in 1966 led to the nomenclature of “autoimmune chronic active hepatitis” for the first time, in order to distinguish it from systemic lupus erythematosus . The discovery of hepatitis A and B viruses allowed hepatitis caused by these viruses to be excluded. Histologically, the term “chronic persistent hepatitis” was used when the mononuclear inflammation was limited to the portal tracts, while the term “chronic active hepatitis” was used to characterize infiltration of the adjacent hepatic parenchyma (piecemeal necrosis) . Widespread acceptance of the autoimmune basis of this condition was accepted only after controlled trials demonstrated response to immunosuppression and a link with human leukocyte antigens (HLA) HLA-B8 and HLA-DR3 was established. The discovery of hepatitis C virus in 1989 led a panel of international experts, the International Autoimmune Hepatitis Group (IAIHG), to formulate several recommendations regarding the diagnosis and classification of AIH. The IAIHG developed a scoring system to weigh each clinical, laboratory, and histological finding at presentation as well as the response to corticosteroid therapy .