Autoimmune Pancreatitis.

Autoimmune pancreatitis (AIP) is a rare, heterogeneous, fibroinflammatory disorder of the pancreas. It has gained increasing recognition due to a presentation that can mimic difficult to treat disorders such as pancreatic cancer, cholangiocarcinoma and primary sclerosing cholangitis. In contrast, autoimmune pancreatitis is a benign disease that is very responsive to therapy with corticosteroids. There are two types of AIP. Type 1 disease is the most common worldwide and is associated with extrapancreatic manifestations and elevated levels of IgG4-positive cells. Type 2 AIP is characterized by a paucity of IgG4-positive cells, and is more difficult to diagnose. This review provides an update on the diagnosis, pathophysiology and treatment of AIP, with special emphasis on the two subtypes.