Diagnosis of isolated hilar‐/extrahepatic‐type IgG‐4‐related sclerosing cholangitis can be increased by improved recognition of this condition—A Japanese multicenter analysis.

Background: Patients with isolated IgG4‐related sclerosing cholangitis (IgG4‐SC) often undergo unnecessary resection. The aim of this study was to validate the revised Japanese diagnostic criteria for isolated IgG‐4‐SC and to improve awareness about this condition in the population. Methods: This was a Japanese retrospective multicenter study. We focused on the data and diagnostic yield obtained using the Japanese diagnostic criteria published initially in 2012 and revised later in 2020 for the diagnosis of isolated IgG4‐SC. Results: Patients with isolated IgG4‐SC could be classified into two groups based on the primary location of the lesion: the hilar type (n = 40) and the extrahepatic type (n = 13). In total, 10 patients with the hilar type had undergone unnecessary resection. The revised 2020 criteria are useful for the diagnosis of extrahepatic lesions, which are not included in the 2012 criteria. The need for a steroid trial was reduced from 37.7% when the diagnosis was based on the 2012 criteria to 7.6% when the diagnosis was based on the revised 2020 criteria. The diagnostic specificity also improved from 58.5% for the 2012 criteria to 88.7% for the revised 2020 criteria. Conclusion: Our validation of the 2020 criteria for the diagnosis of IgG4‐SC could contribute to avoiding unnecessary resection in patients with isolated IgG4‐SC, which can be classified into the hilar and extrahepatic types. The 2020 criteria can enhance the diagnosis rate of isolated IgG4‐SC and uncover this tough‐to‐diagnose entity based on inclusion of the imaging findings and decrease the dependence on a steroid trial. [ABSTRACT FROM AUTHOR]