S3314 A Rare Primary Diagnosis of Immunoglobulin G4 Sclerosing Cholangitis

Introduction: We present an unusual case of jaundice leading to a diagnosis of immunoglobulin G4 sclerosing cholangitis (IgG4-SC). Case Description/Methods: A 67-year-old man with a history of moderate alcohol use presents with jaundice, pruritus, muscle aches, and weight loss. Initial labwork reveals elevated alanine transaminase (105 U/L), aspartate transaminase (79 U/L), alkaline phosphatase (982 U/L), and total bilirubin (10.7 mg/dL). Computed tomography shows mild, diffuse intrahepatic biliary ductal dilation with accompanying distal biliary duct stenosis, along with a hepatic hilar mass. Pancreatic tumor marker cancer antigen 19-9 is found to be elevated at 46.4 U/mL. Endoscopic retrograde cholangiopancreatography with stent placement is performed and yields negative tissue biopsies. Initial suspicion is for Klatskin tumor with potential cholangiocarcinoma. One month later, the patient re-presents for elective common and hepatic bile duct resection and reconstruction, along with Roux-en-Y hepaticojejunostomy. Pathology of hilar mass is found to be negative for malignancy at this time and instead reveals IgG4-SC. After loss to follow up, 10 months later, the patient presents with right upper quadrant pain and elevated liver function tests including high alkaline phosphate (2275 U/L) and elevated IgG3 and IgG4 of 196 mg/dL and 140 mg/dL, respectively. The patient is started on prednisone (60 mg daily). Repeat magnetic resonance imaging at this time demonstrates no changes from original imaging. The patient experiences recurrent hyperglycemia on prednisone and thus the dose is reduced. Liver function tests begin to worsen, and so mycophenolate is added (1000 mg twice daily) and a prednisone taper is initiated. Over the next 6 months, alkaline phosphatase progressively trends down to 325 U/L. Treatment results in downward trend of serum IgG3 and IgG4 to 48 mg/dL and 18 mg/dL, respectively, along with improvement of the patient’s symptoms. Discussion: IgG4-sclerosing cholangitis (IgG4-SC) is a rare autoimmune disease characterized by IgG4-positive lymphocyte-mediated stricture and destruction of the biliary duct. Because IgG4-SC shares significant diagnostic and symptomatic overlap with other gastrointestinal pathologies including cholangiocarcinoma, accurately diagnosing it can be a challenge for physicians, impeding initial treatment.