S3300 Cardiac Tamponade: An Atypical Presentation of Type 1 Autoimmune Pancreatitis

Introduction: Autoimmune pancreatitis (AIP) is a rare condition. Type 1 AIP is often associated with extra-pancreatic organ involvement, commonly the liver, bile ducts, salivary glands, and kidneys. Herein, we present a unique case of Type 1 AIP, with an initial presentation of cardiac tamponade. Case Description/Methods: A 46-year-old Haitian man presented to the hospital with 1 week of cough, chest pain, and intermittent syncope. On admission, he was febrile and tachycardic, but otherwise, physical exam was unremarkable. His electrocardiogram demonstrated inferior ST segment elevations, and subsequent echocardiogram displayed a large pericardial effusion with tamponade physiology, requiring emergent pericardiocentesis. Ischemic cardiac evaluation was negative. Pericardial fluid studies revealed an exudative effusion, prompting a broad infectious workup. While there was concern for Mycobacterium tuberculosis (TB) infection, given that he was from an endemic area, TB pericardial fluid polymerase chain reaction testing was negative. A computed tomography abdomen and pelvis was obtained and revealed a hypo-enhancing pancreatic body lesion encasing the main portal vein and celiac trifurcation. Follow-up magnetic resonance imaging was notable for decreased pancreatic body and tail T1 signal and a large area of decreased enhancement in the body with focal loss of normal acinar parenchyma. There was also evidence of peripancreatic and intrapancreatic edematous changes, as well as poorly organized peripancreatic fluid with normal-caliber ducts. Further serologic testing revealed elevated serum IgG4 of 353.4 mg/dL. Endoscopic ultrasound with Fine needle biopsy (FNB) was performed, demonstrating diffuse echogenicity, hyperechoic strands, hyperechoic foci, and shadowing foci. FNB pathology displayed fibrotic pancreatic tissue with up to 7 IgG4/CD183+ plasma cells and no evidence of malignancy. Given the high likelihood of AIP, he was referred to our pancreatic specialist to consider steroid therapy. Discussion: AIP can be challenging to diagnose; traditionally, patients present with clinical features of abdominal pain, unexplained weight loss, elevated liver tests, or evidence of biliary obstruction. However, confirmatory diagnosis requires supporting evidence on imaging, serological testing, histology, and secondary organ involvement. While pericardial manifestations have been reported with IgG4-related disease, this case highlights a unique, atypical presentation in that the etiology of the cardiac tamponade was only elucidated after imaging, serology, and biopsy of the pancreas supported AIP.