Abstract
Clinical and pathological discriminations between primary sclerosing cholangitis (PSC) and IgG4-related sclerosing cholangitis (IgG4-SC) are important, because therapeutic strategies are different for these disease entities. PSC is pathologically characterized by lymphoplasmacytic infiltration, mucosal erosion, and frequent association with biliary intraepithelial neoplasia. In contrast, IgG4-SC shows diffuse lymphoplasmacytic infiltration containing abundant IgG4-positive plasma cells, diffuse thickening of bile duct wall, and obliterative phlebitis. These two disease entities are pathologically quite different, but discrimination only by non-invasive examination is sometimes difficult. We have to carefully diagnose sclerosing cholangitis based on clinical, radiological and pathological features. Different pathogenetic processes might be involved in PSC and IgG4-SC. Regulatory T cells are decreased around bile ducts in PSC, whereas these cells are increased in the affected bile ducts of IgG4-SC. Interestingly, expression of Th2 and regulatory cytokines, such as IL-4, IL-5, IL-13, IL-10, and TGF-beta1, was increased in IgG4-SC compared to PSC. Overexpression of IL-10 and TGF-beta1 might be involved in IgG4-production and fibroplasia, because IL-10 and TGF-beta1 induces IgG4 class-switch and activation of fibroblasts, respectively.
