Difference from Bile Duct Cancer and Relationship between Bile Duct Wall Thickness And Serum IgG/IgG4 Levels in IgG4-Related Sclerosing Cholangitis

Background/Aims: IgG4-related sclerosing cholangitis (IgG4-SC) is a newly established entity. The purpose of this study was to investigate the differences in intraductal ultrasonography (IDUS) findings between IgG4-SC and bile duct (BD) cancer (BDC) as well as the relationship among BD wall thickness, serological and pathological findings in IgG4-SC. Methodology: Based on the diagnostic criteria of IgG4-SC, we reviewed patients in our hospital between April 2005 and June 2013, and analyzed the data obtained from 32 patients with IgG4-SC and 40 patients with BDC. Results: Regarding IDUS findings, significantly more cases in BDC indicated rigid/papillary inner margin than in IgG4-SC, while biopsy was more efficient. There were no significant correlations between BD wall thickness and serum IgG/IgG4 levels or the number of IgG4-positive cells of the BD specimens. All the IgG4-SC patients without steroid treatment revealed discordant results in the shifts of IgG, IgG4 and BD wall thickness between the 1st and 2nd examinations, while all patients with steroid had completely concordant results of the shifts. Conclusions: IDUS findings alone are insufficient for differentiation between IgG4-SC and BDC. BD wall thickness, serum IgG and IgG4 proportionally shift and reflect the effect of steroid on IgG4-SC after steroid treatment, not before it.