Tissue Acquisition for Histologic Diagnosis
IgG4-SC is a characteristic type of sclerosing cholangitis with increased serum IgG4 levels and dense infiltration of IgG4-positive plasma cells with extensive fibrosis in the bile duct wall. Histopathologic examination is always necessary for the definite diagnosis of IgG4-SC if there are no other organ involvements such as type 1 AIP, IgG4-related sialadenits or retroperitoneal fibrosis. Endobiliary biopsy by ERC is a standard technique for tissue acquisition of bile duct. However, it is not easy to obtain sufficient bile duct tissue to study the characteristic histology of IgG4-SC biopsy specimens because fibroinflammatory involvement is observed mainly in the submucosa of the bile duct wall, whereas the epithelium of the bile duct is sometimes intact. Liver biopsy can be useful and diagnostic if IgG4-SC involve intrahepatic small bile duct and be considered as a last tissue acquisition method if endobiliary biopsy is nondiagnostic.