Journey to diagnosis: An unfinished exploration of IgG4-related sclerosing cholangitis.

IgG4-related sclerosing cholangitis (IgG4-SC) is an inflammatory disease that leads to bile duct stricture, characterized by the infiltration of IgG4-positive plasma cells into the bile duct wall, thickening of the bile duct wall, and narrowing of the lumen. The differential diagnosis of IgG4-SC mainly includes primary sclerosing cholangitis, cholangiocarcinoma, and pancreatic cancer. IgG4-SC is often associated with autoimmune pancreatitis and can be accurately diagnosed based on clinical diagnostic criteria. However, isolated IgG4-SC is difficult to distinguish from biliary tumors. Given the significant differences in biological behavior, treatment, and prognosis between these diseases, accurately identifying isolated IgG4-SC has very important clinical significance.