Overlap syndromes of autoimmune hepatitis: what is known so far.

The pattern of some autoimmune hepatitis can be difficult to classify, sometimes due to the overlap of these with primary biliary cirrhosis, primary sclerosing cholangitis and chronic viral hepatitis. The etiology of these variant forms remains unclear. The distinction among the overlap syndromes poses different problems both of prognosis and therapeutic approach. Presently, the utility of the scoring system devised and revised by the International Autoimmune Hepatitis Group regarding these cases is under discussion. Histological examination seems to be an important tool, but often the result does not help in defining a correct diagnosis. To date, the overlap syndromes can be classified at an intermediate level between cholestatic forms of autoimmune hepatitis or hepatic forms of cholestatic syndromes, but it cannot be excluded that the syndromes represent independent disorders.