Autoimmune pancreatitis, also called AIP, is a chronic inflammation that is thought to be caused by the body's immune system attacking the pancreas and that responds to steroid therapy. Two subtypes of AIP are now recognized, type 1 and type 2.
Type 1 AIP is also called IgG4-related pancreatitis and is part of a disease called IgG4-related disease (IgG4-RD) that often affects multiple organs including the pancreas, bile ducts in the liver, salivary glands, kidneys and lymph nodes.
Type 2 AIP, also called idiopathic duct-centric pancreatitis, seems to affect only the pancreas, although about one-third of people with type 2 AIP have associated inflammatory bowel disease.