The fact that three patients with elevated sIgG4 had abnormal pancreatic imaging suggests that some patients could have had undiagnosed IAC. However, none of the resected bile ducts Roscovitine clinical trial showed evidence of IAC despite staining for IgG4, which would

argue against this hypothesis. Finally, we found no association of elevated sIgG4 levels with stricture distribution (intra- or extrahepatic) and no correlation between sIgG4 and CA19-9 level in CCA patients. We also found no evidence of association of an overlap syndrome of autoimmune hepatitis in conjunction with PSC with elevated sIgG4 levels in CCA patients. In summary, we have demonstrated the following findings relating to sIgG4 in cholangiocarcinoma: (1) sIgG4 is elevated in a subset of patients with CCA; (2) CCA patients with concomitant PSC (CCA+PSC) are more likely to exhibit higher sIgG4 levels than those without PSC (CCA-PSC); (3) in order to more

reliably distinguish IAC from CCA based on sIgG4 alone, an IgG4 cutpoint of at least twice the upper limit of normal is required. However, at approximately four times the upper limit of normal, sIgG4 is 99%-100% specific for distinguishing IAC from CCA. In view of the similar clinical and radiologic features of CCA and IAC, CCA should be carefully ruled out in patients with suspected IAC whose sIgG4 is only mildly elevated, particularly when they do not fully meet the HISORt criteria required to diagnose IAC. This distinction FG-4592 molecular weight is important in view of the use of steroids to manage IAC, which may result in delays in administering appropriate treatment of CCA. Secretarial

assistance: Victoria L. Campion and Erin Fairchild. Author contributions: Abdul M Oseini: Study concept and design; acquisition of data; analysis and interpretation of data; drafting of the article; statistical analysis. Roongruedee Chaiteerakij: Study concept and design; acquisition of data; analysis and interpretation of data; drafting of the article; statistical analysis. Abdirashid M. Shire: Acquisition of data; critical revision of the article for important intellectual content. Amaar Ghazale: Study concept and design; acquisition of data; critical selleckchem revision of the article for important intellectual content. Kaiya Joseph: Acquisition of data; critical revision of the article for important intellectual content. Catherine D Moser: Acquisition of data; critical revision of the article for important intellectual content. Ileana Aderca: Acquisition of data; critical revision of the article for important intellectual content. Teresa A Mettler: Acquisition of data; critical revision of the article for important intellectual content. Terry M Therneau: Statistical analysis and interpretation of data; critical revision of the article for important intellectual content. Lizhi Zhang: Tissue staining and pathological analysis; critical revision of the article for important intellectual content.