IgG4-related diseases and the liver

IgG4-related disease (IgG4-RD) is a systemic illness including autoimmune pancreatitis and IgG4-related sclerosing cholangitis (IgG4-SC). Although hepatic presentation of IgG4-RD has been reported, whether intrahepatic small bile ducts and hepatocytes are direct targets of IgG4-RD is uncertain. IgG4-RD is pathologically characterized by the numerous IgG4+ cells found in affected organs, but this IgG4 positivity is also frequently found in extrahepatic cholangiocarcinoma and is prominent, albeit rarely, in other hepatobiliary diseases including primary sclerosing cholangitis and autoimmune hepatitis. Moreover, cholangiocarcinoma arising from precedent IgG4-SC and IgG4-SC accompanying precursor lesions of cholangiocarcinoma (biliary intraepithelial neoplasia) are also reported. Diagnostic criteria for IgG-RD and IgG4-SC were recently proposed, but each individual case should be diagnosed clinicopathologically on the basis of its individual features. © Springer Japan 2016.[Book Chapter