Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a particular form of immune-mediated inflammatory disease of the pancreas characterized by histological features of lymphoplasmacytic infiltrate and fibrosis and excellent response to corticosteroid therapy. AIP is considered a rare entity, and it is generally presented with obstructive jaundice associated with an inflammatory pancreatic mass or an inflammatory stricture of the bile duct. There are two types of AIP, which differ in their epidemiology, pathological features, and clinical manifestations. Type 1 AIP is part of the IgG4-related systemic disease, whereas type 2 AIP is a specific pancreatic disorder. AIP diagnosis is challenging, especially because its clinical and radiological manifestations can mimic pancreatic and biliary cancer, which often leads to unnecessary pancreatic surgery, but it can also contribute to delayed diagnosis of biliopancreatic malignancy. AIP diagnosis is based on a consensus of clinical, serological, imaging, and pathologic criteria as well as response to corticosteroids.