IgG4-Related Autoimmune Pancreatitis Mimic Pancreatic Tumor with Aortitis — A Case Report

IgG4-related diseases (IgG4-RD) are a spectrum of diseases involving many organs. Type 1 autoimmune pancreatitis is the most common disease of IgG4-RD. It often presents with obstructive jaundice and swelling of the pancreas. We report a case of a 56-year-old male with initial presentation of epigastric pain. Endoscopic abdominal sonogram, CT scan and MRI revealed a tumor over pancreatic tail. Pancreatectomy was done and the pathological report revealed IgG4-related autoimmune pancreatitis. In addition, wall thickening of the infra-renal abdominal aorta was also noted, and aortitis was diagnosed. The case emphasizes autoimmune pancreatitis be present with a pseudotumor and complete studies like IgG subclasses, including IgG4, should be included. (J Intern Med Taiwan 2015; 26: 169-173)