Bile Usefulness for Detecting IgG4-related Sclerosing Cholangitis

Immunoglobulin G4-related disease (IgG4-RD) is an uncommon inflammatory disorder that may affect multiple organ systems, including the biliary tree. IgG4-sclerosing cholangitis (IgG4-SC) can be difficult to distinguish from primary sclerosing cholangitis (PSC) or cholangiocarcinoma (CCA). The investigators aim to evaluate the sensitivity and specificity of bile for the diagnosis of IgG4-SC. Bile samples of patients with biliary strictures of various causes, including IgG4-SC, PSC, and CCA, will be collected during clinical cholangiography procedures. IgG4 will be measured in bile specimens and bile IgG4 concentrations compared between IgG4-SC, PSC, CCA, and other types of biliary strictures.