S1694 IgG4-Related Sclerosing Cholangitis - An EUS Diagnosis

Abstract

Introduction: Sclerosing cholangitis is a heterogenous disease associated with choledocholithiasis, biliary tumor or infection. The participation of IgG4 subclass in the pathology of sclerosing cholangitis is typically associated with autoimmune pancreatitis (60%), sialadenitis (34%), tubulo-interstitial nephritis (23%) and peri-aortitis (20%). Isolated lower duct IgG4 related sclerosing cholangitis (IgG4-Sc) is extremely uncommon and we present one such rare case. Case Description/Methods: A 73-year-old former smoker presents with complaints of yellowish discoloration of the skin and decreased appetite for a month. He has lost 44 lbs and endorses diarrhea. His family history is remarkable for lung cancer and kidney disease. Laboratory data shows cholestatic jaundice- total bilirubin of 14.2 mg/dL, AST 61 U/L, ALT 60 U/L and Alkaline phosphatase 328 U/L. CT Abdomen and Pelvis shows intra and extra-hepatic biliary ductal dilatation with common bile duct distension up to 1.4 cm. Subsequent MRCP notable for focal wall thickening involving the mid and lower portion of the common bile duct causing severe stenosis, concerning for CBD malignancy. ERCP shows proximal dilatation of the CBD with stricture of the distal end of bile duct. Biopsies obtained from the stricture were negative and tumor markers showed CEA 2.4 and CA 19-9 212. ANA screen was positive with high DsDNA antibody and elevated IgG4 at 761 mg/dL. Serum lipase was normal, anti-smooth muscle antibody and anti-mitochondrial antibody were negative. He subsequently underwent EUS/ERCP, and the CBD stricture and peri-portal lymph nodes were biopsied. Pathology from CBD stricture showed fibrosis and chronic inflammation with increased IgG4 positive plasma cells by immunohistochemistry. Hence, the patient was diagnosed with IgG4-related sclerosing cholangitis and initiated on 40 mg of Prednisone. Discussion: IgG4 related disease is a multiorgan fibro-inflammatory disease that involves infiltration of IgG4 positive plasma cells into multiple organs. IgG4-Sc is observed in elderly men who present with obstructive jaundice. HISORt criteria is used to make the diagnosis and was initially designed for diagnosis of autoimmune pancreatitis. Radiographically, Type 1 IgG4-Sc involves stenosis of only the lower bile duct and may resemble cholangiocarcinoma. Additionally, IgG4 levels may be normal further confounding the diagnostic picture. A high degree of clinical suspicion and biopsy (via EUS guidance or cholangioscopy) is imperative in making a diagnosis.Figure 1.: Endoscopic ultrasound revealing pancreatic body pseudocyst measuring 11x10 cm in diameter.