Liver Biopsy as a Useful Tool in the Management of Autoimmune Liver Diseases in Childhood

Abstract

Autoimmune diseases of the liver and biliary tract are inflammatory diseases of unknown origin that progress spontaneously, in most cases, to severe fibrosis and cirrhosis (Maggiore et al, 2009). They are characterized by an inflammatory infiltrate in the liver tissue involving the lobule and the portal tract and, most frequently, by the presence of non-organ and liverspecific autoantibody reactivity (Mieli Vergani & Vergani, 2009). There are at least three principal disorders in humans, in which the liver damage is thought to be caused by an autoimmune mechanism: autoimmune hepatitis (AIH), where the target of the autoimmune attack is the hepatocyte, and two other conditions, autoimmune cholangitis (AIC) and primary biliary cirrhosis (PBC), where the target is the cholangiocyte. Between these three disorders exists a range of overlap of liver damage both at diagnosis and/or during the follow-up, recognized as “overlap syndrome” (Alvarez, 2006). Any autoimmune disorder may overlap with the other two. Autoimmune cholangitis may be limited, at diagnosis and during the follow-up, to the smallest intrahepatic (forth order) bile ducts in case of the socalled “small duct sclerosing cholangitis” (Chapman, 2002), or may be diffuse affecting also larger bile duct and giving the typical radiological or MRI imaging of “sclerosing cholangitis”). In children, primary biliary cirrhosis is exceptionally described, particularly before adolescence. Moreover, a rare and peculiar form of autoimmune hepatitis, typical of infancy exists, and is characterized by the unique association of Coombs positive autoimmune hemolytic anemia with the peculiar histopathological finding of diffuse giant cell transformation of the hepatocytes at a very unusual age even for infants (Maggiore et al, 2011). Immunosuppressive treatment is usually efficacious in most cases of AIH, but it is less effective in autoimmune cholangitis, particularly in case of delayed diagnosis at the stage of diffuse sclerosing cholangitis (Maggiore et al, 2009). Immunosuppressive treatment is also the only life-saving treatment recognized in “infantile giant cell hepatitis associated with autoimmune hemolytic anemia” (Maggiore et al, 2011). Liver biopsy is of paramount importance in the diagnostic work-up of autoimmune diseases of the liver and biliary tract as recognized by the major guidelines. Histological examination