Pathologists are likely to encounter IgG4-related disease in several organ systems. This article focuses on helping pathologists diagnose IgG4-related disease in the hepatobiliary system. Missing the diagnosis can result in unnecessary organ damage and/or unnecessary surgical and cancer therapy. In the liver, tumefactive lesion(s) involving the bile ducts with storiform fibrosis and an IgG4-enriched lymphoplasmacytic infiltrate are highly concerning for IgG4-related disease. The recent identification of oligoclonal populations of T cells and B cells in IgG4-related disease may lead to molecular tests, new therapeutics, and a greater mechanistic understanding of the disease.
Keywords: Autoimmune pancreatitis; IgG4; IgG4-related disease; IgG4-related sclerosing cholangitis; Primary sclerosing cholangitis.
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