Autoimmune hepatitis and its variant syndromes

The characteristic features of the variant syndromes of AIH are summarised in table 1. The presence of AMA, histological features of cholangitis, abnormal cholangiogram, disproportionate elevation of the serum alkaline phosphatase level, laboratory features of cholestasis, and/or concurrent true viral infection in individuals who otherwise have classical features of AIH constitute the variant forms. The variant syndromes are in part the result of improved diagnostic criteria that exclude patients with cholestatic and viral features from the diagnosis of AIH. Their frequency emphasises the variability of the classical syndromes of autoimmune liver disease, and it suggests that the classical disorders share genetic predispositions and/or pathogenic mechanisms that can result in hybrid syndromes, concurrent diseases, or transition states. The variant syndromes should be classified separately until their nature is fully defined. In this fashion, the natural history of the established disorders can be preserved, and the pathogenic pathways of the newly recognised entities examined. Treatments are empiric until diagnostic criteria can be codified and multicentre clinical trials instituted. The variant syndromes may reflect the "larval stage" of a classical syndrome, a collage of different autoimmune manifestations in a susceptible host, a unique expression of coincidental factors that are unrelated, or an independent complex disorder with a heterogeneous phenotype. Each syndrome should stand alone until its true identity is revealed.