Clinical features of isolated proximal-type immunoglobulin G4-related sclerosing cholangitis.

Background And Aim: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) presents as isolated proximal-type sclerosing cholangitis (i-SC). The present study sought to clarify the imaging differences between i-SC and Klatskin tumor. Differences between i-SC and IgG4-SC associated with autoimmune pancreatitis (AIP-SC) were also studied.

Methods: Differentiating factors between i-SC and Klatskin tumor were studied. Serum IgG4 level, CA19-9 level, computed tomography (CT) findings, cholangiography findings (symmetrical smooth long stricture extending into the upper bile duct [SSLS]), endosonographic features (continuous symmetrical mucosal lesion to the hilar part [CSML]), endoscopic biopsy results, treatment, relapse, and survival were also compared between patients with i-SC and those with AIP-SC.

Results: For a differential diagnosis between i-SC (N = 9) and Klatskin tumor (N = 47), the cut-off value of serum IgG4 level was 150 mg/dL (sensitivity, 0.857, specificity, 0.966). Logistic regression analysis indicated that serum IgG4 level, presence of SSLS, presence of CSML, and presence of swollen ampulla are independent factor for identifying i-SC. Relapse rate was significantly higher in the IgG4-SC with AIP group than in the i-SC group (log rank, P = 0.046).

Conclusion: Isolated proximal-type sclerosing cholangitis presents as a nodular lesion with SSLS and/or CSML mimicking a Klatskin tumor. Those endoscopic features might provide a diagnostic clue for i-SC. i-SC is likely to have a more favorable prognosis than IgG4-SC with AIP.