Liver biopsy interpretation in the differential diagnosis of autoimmune liver disease in children

Abstract

Autoimmune liver disease (AILD) represents a group of complex inflammatory liver diseases, all characterized by an aberrant autoreactivity against hepatocytes and/or biliary structures. AILD may be subclassified into four major diseases: autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and autoimmune cholangitis (AIC). Recently a new entity frequently associated with autoimmune pancreatitis and defined IgG4-related cholangitis (IgG4-RC), has been added to the spectrum of AILD. The most frequent autoimmune liver diseases of the AILD spectrum occurring in children and in young adults are AIH and PSC, overlap syndrome between AIH and PSC, also defined as autoimmune sclerosing cholangitis (ASC), representing a frequent finding in pediatric patients. Here, the morphological findings that may help liver pathologists in the differential diagnosis of AILD in pediatric patients are reviewed, underlying the frequency in liver biopsy interpretation of complex cases in which a precise diagnosis may remain controversial, due to overlap of hepatocytic and bile duct cell lesions. Among the multiple morphological changes typical of AILD, the detection of an high number of plasma cell clusters in the portal and periportal regions is generally considered one of the main clue for the diagnosis of AIH. The recent report in a 13-year old boy of IgG4-associated cholangitis, induces pathologists when detecting a huge number of plasmacells, to consider the differential diagnosis between AIH and IgG4-RC. Proceedings of the 9 th International Workshop on Neonatology · Cagliari (Italy) · October 23 rd -26 th , 2013 · Learned lessons, changing practice and cutting-edge research