S1477 A Spy Took a Bite to Get the Dx Right - A Case of Idiopathic Pancreatitis

Abstract

INTRODUCTION: Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis that is infrequently recognized and is characterized clinically by frequent presentations with obstructive jaundice. Serum IgG4 testing as a means to “rule out” IgG4 related disease may not be as helpful as initially thought and may lead to inappropriate lack of diagnosis if suspicion is low. CASE DESCRIPTION/METHODS: A 40-year-old white male with GERD, chronic portal vein thrombosis, history of alcoholism, and chronic pancreatitis (since 2015) presents with nausea, vomiting, chills, and epigastric pain radiating to the back. He has had 8 episodes in the last year and required biliary stenting for multiple biliary strictures. He denied fever, dyspnea, chest pain, hematemesis, melena, alcohol use, scorpion sting, and trauma. Labs were significant for TRG 172, Ca 8.6, Lipase 239, AST 34, ALT 37. CT of the abdomen showed acute on chronic pancreatitis with a stable biliary stent. Previous workup for pancreatitis included normal TRG and calcium levels, lack of cholelithiasis, no inciting medications or infection, and serum IgG4 level of 7.3 (normal: 2-120). After admission, lipase increased to 1321 with worsening AST/ALT and bilirubin concerning for obstruction prompting Magnetic Resonance Cholangiopancreatography (MRCP). MRCP demonstrated extensive retroperitoneal inflammation and obstruction of the biliary stent. Endoscopic retrograde cholangiopancreatography (ERCP) with SpyGlass direct visualization revealed an occluded biliary stent, multiple strictures, and exophytic tissue in the lower common bile duct which was biopsied with SpyBite. The strictures were dilated, the stent was exchanged, and the biopsies were sent for pathology. Pathology returned negative for malignancy but stained positive for IgG4 and the patient was initiated on systemic steroid therapy. DISCUSSION: With recurrent pancreatitis, classic histological findings, biliary strictures, cholangitis, and improvement with steroids in the setting of normal serum IgG4 levels; this complex patient represents a challenging case of type 1 AIP. A 2016 meta-analysis found that serum IgG4 had 87% sensitivity 83% specificity for IgG4-RD (1). Other studies suggest that many (as much as 33%) patients with biopsy-proven IgG4-RD have normal serum IgG4 (2). With these findings, we believe it is imperative that others give further consideration to tissue sampling in similar patients with difficult to define pancreatitis.Figure 1.: MRI Abd w CBD stent mass and pneumobilia.Figure 2.: Mass in CBD.Figure 3.: IgG4 stain positive tissue from CBD mass.