Autoimmune pancreatitis associated with IgG4-related cholangitis: A radiologic-serologic correlation.

Autoimmune pancreatitis (AIP) is a rare fibro-inflammatory disease that may closely mimic pancreatic malignancy, making accurate diagnosis challenging. We report the case of a 42-year-old man presenting with acute epigastric pain, elevated serum lipase levels, and imaging initially suggestive of acute interstitial pancreatitis. Magnetic resonance imaging revealed diffuse pancreatic enlargement with diffusion restriction, a peripheral capsule-like rim, and a tapered stenosis of the main pancreatic duct, associated with circumferential thickening of the bile duct walls and upstream intrahepatic bile duct dilatation. These imaging findings raised the suspicion of type 1 AIP associated with IgG4-related cholangitis. The diagnosis was confirmed by elevated serum IgG4 levels. This case highlights the importance of correlating characteristic pancreatic and biliary imaging features with serological findings to avoid misdiagnosis and unnecessary surgical management.