IgG4-associated sclerosing cholangitis masquerading as hilar cholangiocarcinoma.

IgG4-sclerosing cholangitis (IgG4-SC) commonly presents with type 1 autoimmune pancreatitis. Isolated IgG4-SC is rare. Differentiating IgG4-SC from cholangiocarcinoma preoperatively is challenging due to overlapping radio-clinical manifestations and difficult preoperative histology. We present three cases preoperatively diagnosed and surgically treated as hilar cholangiocarcinoma. First and second cases presented with cholangiocarcinoma with portal vein involvement and third with a malignant-appearing hilar stricture. On histopathology, IgG4-SC was diagnosed in the first two cases. Third patient had raised serum IgG4, and histopathology was inconclusive for IgG4-SC and negative for malignancy. However, she responded to steroid therapy.