*Section of Hepatobiliary and Pancreatic Surgery, Division of Surgical Oncology, University of Virginia, Charlottesville, VA, USA
†Division of Gastroenterology and Hepatology, University of Virginia, Charlottesville, VA, USA
‡Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA
§Department of Pathology, University of Virginia, Charlottesville, VA, USA
IgG4-associated cholangitis can mimic hilar cholangiocarcinoma. Previously reported patients with IgG4-associated cholangitis mimicking cholangiocarcinoma had elevated serum IgG4 levels and long-segment biliary strictures. However, in the absence of other diagnostic criteria for malignancy, IgG4-associated cholangitis should remain a consideration among patients with normal serum IgG4 and a hilar mass suspicious for cholangiocarcinoma. The presence of a hilar mass and a malignant-appearing biliary stricture in two patients with normal serum IgG4 prompted further evaluation and subsequent concomitant liver and bile duct resection and reconstruction. The diagnosis of IgG4-associated cholangitis was established during the pathologic evaluation of the resected specimens. IgG4-associated cholangitis is a known imitator of hilar cholangiocarcinoma and should be considered in the differential diagnosis even among serologically IgG4-negative patients with a hilar mass prior to operative resection.