Measurement of IgG4 in bile: A new approach to diagnose IgG4-associated cholangiopathy

Introduction: Immunoglobulin G4 associated cholangitis (IAC) is difficult to diagnose, as the associated biliary tract strictures can not be differentiated from cholangiocarcinoma (CC) or primary sclerosing cholangitis (PSC) by cholangiography. Serum IgG4 levels show a low sensitivity and specificity and are unreliable in particular in patients with related diseases, e.g. PSC. As IAC takes place at the biliary epithelium, we hypothesized that IgG4 measurement in bile may have higher sensitivity in comparison to serum. Methods: Bile and serum samples were collected during cholangiography in 67 patients including…