Background: IgG4-related sclerosing cholangitis (IgG4-SC) needs to be differentiated from pancreatic cancer (PCa), primary sclerosing cholangitis (PSC), and cholangiocarcinoma (CC). We attempted to establish diagnostic criteria for IgG4-SC based on cholangiographic classification by comparison with several diagnostic modalities.
Methods: We classified 62 IgG4-SC patients into three groups on the basis of cholangiographic findings to allow differentiation from PCa, PSC, and CC: Group A IgG4-SC showed features similar to PCa (Type 1, n = 32), Group B showed similarity to PSC (Type 2, n = 15), and Group C showed similarity to CC (Type 3, 4, n = 15). Thirty-five patients with PCa, 40 with PSC, and 32 CC were enrolled as controls. We retrospectively compared the clinical, imaging, serological, and histopathological features and involvement of other organs between Group A and PCa, Group B and PSC, and Group C and CC.
Results: Association with autoimmune pancreatitis (AIP) (P < 0.001) and involvements with other organs (specificity 100%) were common useful diagnostic parameters in all three IgG4-SC groups. A high serum IgG4 level was a useful parameter in Groups A and B (P < 0.001). Discriminant analysis of cholangiograms (P < 0.001), liver biopsy (specificity 100%), and exclusion of inflammatory bowel disease (specificity 100%) were useful parameters in Group B. Intraductal ultrasonography findings (P < 0.001) and exclusion of malignancy by bile duct biopsy (specificity 100%) were useful parameters in Group C. We established diagnostic criteria for IgG4-SC (sensitivity 100%, specificity 96.3%) by incorporating parameters that showed P < 0.001 or 100% specificity.
Conclusions: Diagnostic criteria for IgG4-SC based on cholangiographic classification are useful for distinguishing it from PCa, PSC, and CC.