THU369 A Rare Case Of IgG4-related Autoimmune Pancreatitis And Diabetes Mellitus

Disclosure: M. Zahid: None. J. Shakil: None. Introduction: IgG4 related disease (IgG4-RD) is a rare multiorgan inflammatory condition characterized by dense lymphoplasmacytic infiltrates, presence of IgG4+ plasma cells and fibrosis. Here we present a case of young male with painless jaundice and hyperglycemia diagnosed with IgG4 related autoimmune pancreatitis and DM. Clinical Case: 46-year-old male with no significant history presented to outpatient clinic for pruritis and dark-colored urine of 2-week onset. He reported 17-pounds weight loss in the preceding month. While undergoing outpatient workup, patient developed epigastric pain prompting visit to the hospital. On examination, patient was afebrile, tachycardiac, icteric and had epigastric tenderness. Labs revealed normal electrolytes and renal function. LFTs were significant for total protein 7.6 g/dl (n=6.3-8.3 g/dl), AST 77 U/L (n = 10-50 U/L), ALT 127 U/L (n = 5-50 U/L), alkaline phosphatase 458 U/L (n = 40-129 U/L) and direct bilirubin >10.0 (n = 0-0.3 mg/dl). Lipase was 99 U/L (n - 13-60 U/L), blood glucose was 292 mg/dl and A1C was 6.5% (n = 4.0-5.6%). US abdomen revealed diffuse gallbladder wall thickening with moderate sludge and intrahepatic and extrahepatic distal biliary obstruction and dilatation. MRCP showed common bile duct and intrahepatic biliary ductal dilation. Pancreas was diffusely irregular with areas of hemorrhagic pancreatitis. ERCP showed dilatation of upper and middle third of main bile duct, left and right hepatic ducts and all intrahepatic branches with a stricture in distal bile duct. Biliary sphincterotomy and placement of temporary plastic biliary stent was performed and ampullary biopsies were taken. IgG4 level was checked due to suspicion for IgG4-RD and was 293 mg/dl (n: 1-123 mg/dl). Pathology revealed mucosa with epithelial reactive changes. CD138 stain showed several mature plasma cells within the inflammatory infiltrate. In addition, immunostain for IgG4 shows several IgG4 positive plasma cells forming small clusters confirming diagnosis of IgG4-RD. Post procedure, his abdominal pain and LFTs started improving. Patient was started on prednisone for IgG4-RD and insulin for persistent hyperglycemia. His prednisone dose was later tapered after starting methotrexate. Patient’s most recent LFTs have normalized except mildly elevated ALT and A1C improved to 6.2%. Conclusion: Autoimmune pancreatitis and cholangiopathy are the pancreatobiliary manifestation of IgG4-RD and most often present as painless jaundice mimicking pancreatic cancer. Endocrine insufficiency usually manifests as diabetes mellitus/pre-diabetes and may also lead to autoimmune hypophysitis and Reidel’s fibrosis. Other organ systems that may also get involved include lacrimal and salivary glands, lungs, kidneys, nervous system, and lymphatic/vascular system. Early recognition and ongoing surveillance are key to appropriate management of this condition. Presentation: Thursday, June 15, 2023