Small bile duct involvement in IgG4-related sclerosing cholangitis: liver biopsy and cholangiography correlation.

Background: IgG4-related sclerosing cholangitis (IgG4-SC) needs to be differentiated from primary sclerosing cholangitis (PSC). In this study, we performed a retrospective study to reveal cases in which liver needle biopsy was useful for differential diagnosis.

Methods: Nineteen patients with IgG4-SC and 22 patients with PSC were studied. All patients underwent endoscopic retrograde cholangiography and liver needle biopsy. We defined small bile duct involvement of IgG4-SC histologically as damage to the small bile duct associated with infiltration of ≥10 IgG4+ plasma cells per high power field (HPF). Clinicopathological characteristics were compared between IgG4-SC patients with and without small bile duct involvement.

Results: Small bile duct involvement was observed in 5 (26%) of the patients with IgG4-SC. Patients with small bile duct involvement showed a higher incidence of intrahepatic biliary strictures on cholangiography (80 vs. 21%, p = 0.038). Conversely, 4 of 7 (57%) patients with intrahepatic biliary strictures on cholangiography had histologically evident small duct involvement. The number of IgG4+ plasma cells was significantly correlated with the site of the most proximal stricture on cholangiograms (p = 0.021). The number of IgG4+ plasma cells per HPF was significantly higher in IgG4-SC patients with intrahepatic biliary strictures than in those with PSC (13.4 vs. 0.4 cells/HPF, p < 0.001).

Conclusions: Involvement of small bile ducts is more frequent in patients with intrahepatic biliary strictures on cholangiography, and liver needle biopsy is especially useful for these patients.