1273 IgG4 Related Cholangiopathy Masquerading as Cholangiocarcinoma

Abstract

INTRODUCTION: IgG4 related diseases can involve multiple organs, best described in cases of autoimmune pancreatitis (AIP). IgG4-related cholangiopathy is difficult to distinguish from other forms of biliary ductal disorders including primary biliary cholangitis, primary sclerosing cholangitis (PSC), and cholangiocarcinoma (ChCA). Specifically, IgG4 cholangiopathy and ChCA share many clinical and imaging findings which make it difficult to distinguish these entities. We report a rare case of IgG4 cholangiopathy mimicking a ChCA. CASE DESCRIPTION/METHODS: A 69-year-old male presented with nausea/vomiting, weight loss, painless jaundice, and CT suggestion of a malignant hilar mass. ERCP with cytology and EUS with FNA from the hilar mass were negative for malignancy. Two further ERCPs with Spyscope hepatic duct bifurcation biopsies showed severe stenosis of the right hepatic ducts and diffuse biliary stricturing suggestive of PSC. Brushings for cytology and fluorescence in situ hybridization (FISH) were obtained, balloon dilation and stenting performed. MRCP noted multifocal intrahepatic biliary strictures, suggestive of PSC; a hilar mass, as seen on CT, was not seen. The MR suggested a solid pancreatic uncinate process mass. A repeat EUS showed changes of chronic pancreatitis but no mass. A comprehensive review of the combination of intrahepatic strictures, pancreatic atrophy and uncinate mass suggested a diagnosis of IgG4 disease; an ANA was positive at 1:160 and IgG4 was elevated at 1,250 mg/dL (normal < 123). The patient was started on prednisone and had complete resolution of abnormal liver tests, clinical symptoms, MR biliary ductal dilatation, and MR pancreatic mass within 3 weeks. DISCUSSION: While described in AIP, IgG-4 related diseases can affect multiple organs, including kidneys, liver, salivary gland, orbit, breast, pericardium, aorta, skin, lungs, prostate, meninges, and the pituitary gland. IgG4-related cholangiopathy is a distinct yet rare etiology, characterized by elevated serum IgG4 levels and IgG4-positive plasma cell infiltration with storiform fibrosis/obliterative phlebitis of the bile duct wall. It has been identified in patients with concomitant AIP and is steroid responsive. Early diagnosis of IgG4 cholangiopathy avoids prolonged hospitalizations, unnecessary repeated procedures, and morbidity/mortality due to treatment delay We describe a rare case of IgG4 autoimmune cholangiopathy with delayed diagnosis due to concern for ChCA.