IgG4-related sclerosing cholangitis (IgG4-SC) is often associated with autoimmune pancreatitis. However, the diffuse cholangiographic abnormalities observed in IgG4-SC may resemble those observed in primary sclerosing cholangitis (PSC), and the presence of segmental stenosis suggests cholangiocarcinoma (CC). IgG4-SC responds well to steroid therapy, whereas PSC is only effectively treated with liver transplantation and CC requires surgical intervention. Since IgG4-SC was first described, it has become a third distinct clinical entity of sclerosing cholangitis. The aim of this review was to introduce the diagnostic methods for IgG4-SC. IgG4-SC should be carefully diagnosed based on a combination of characteristic clinical, serological, morphological, and histopathological features after cholangiographic classification and targeting of a disease for differential diagnosis. When intrapancreatic stenosis is detected, pancreatic cancer or CC should be ruled out. If multiple intrahepatic stenoses are evident, PSC should be distinguished on the basis of cholangiographic findings and liver biopsy with IgG4 immunostaining. Associated inflammatory bowel disease is suggestive of PSC. If stenosis is demonstrated in the hepatic hilar region, CC should be discriminated by ultrasonography, intraductal ultrasonography, bile duct biopsy, and a higher cutoff serum IgG4 level of 182 mg/dL.
Keywords: IgG4; IgG4-related sclerosing cholangitis; Primary sclerosing cholangitis; Sclerosing cholangitis.