Serum negative immunoglobulin G4-associated cholangiopathy mimicking hilar cholangiocarcinoma: A case report and review

Abstract

Introduction: Immunoglobulin G4-associated cholangiopathy (IAC) is a systemic manifestation of IgG4-related diseases manifesting with an increased serum level of IgG4. Immunoglobulin G4-associated cholangiopathy often has a robust clinical response to steroid therapy, however making a diagnosis can be difficult as the cholangiographic features may resemble that of cholangiocarcinoma with varying immunological profiles. In the absence of features suggestive of malignancy, a high index of suspicion for the disease should be maintained, even in the presence of normal serum levels of IgG4. Case Report: In this case report, the diagnosis of IAC was made following cholangiographic imaging, along with the presence of retroperitoneal fibrosis and thickened urothelia, although serum IgG4 levels were within normal limits. The resolution of biliary strictures following a trial of steroid therapy further confirmed the diagnosis. Conclusion: Immunoglobulin G4-associated cholangiopathy requires a combination of clinical, serological, histopathological, and radiological features in order to make a clear diagnosis. A trial of steroid therapy in the event of an unclear clinical presentation further helps in differentiating IAC from hilar cholangiocarcinoma.