Imaging in Autoimmune Pancreatitis and Immunoglobulin G4-Related Disease of the Abdomen.

Autoimmune pancreatitis (AIP) is steroid-responsive fibroinflammatory disorder of the pancreas. There are 2 distinct subtypes of AIP, types 1 and 2. Type 1 is associated with systemic immunoglobulin (Ig)G4 disease and may affect multiple organs in the body. Type 2 is confined to the pancreas and shows an association with ulcerative colitis. This article describes the imaging findings of AIP and IgG4 disease in the liver, bile ducts, kidneys, and the retroperitoneal regions. The imaging differentiation of AIP from pancreas cancer is discussed.