Overview
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.
Autoimmune pancreatitis is a rare, newly recognized disease and can be mistakenly diagnosed as pancreatic cancer. The two conditions have similar signs and symptoms, but very different treatments, so it is very important to distinguish one from another.
Source: http://www.mayoclinic.com