[Autoimmune pancreatitis today: clinical features and diagnostic strategies]

Autoimmune pancreatitis (AIP) is a particular form of chronic pancreatitis recognized as clinical entity only in recent decades. Peculiar clinical, serological, histological and radiological features make it different from other types of pancreatitis. The diagnosis of AIP represents a challenge for the clinicians. Particularly in its focal form, it shows several features in common with pancreatic adenocarcinoma. Both of these conditions, in fact, are often associated with obstructive jaundice, cause increase of the volume of the pancreas and can share the radiologic appearance of a focal mass. The autoimmune pancreatitis instead of pancreatic cancer regresses promptly after treatment with oral corticosteroids. Because of the different management of the two diseases a correct differential diagnosis is imperative. From 5% to 21% of AIP cases are diagnosed in patients after pancreatic resection performed for suspected malignancy. Still not identified a specific serological marker of AIP which can allow a definitive diagnosis of the disease. Both the diagnosis of pancreatic cancer as AIP is paid on the basis of different clinical tests: the diagnosis of pancreatic cancer requires imaging studies, laboratory tests and biopsy of the pancreas, while the diagnosis of AIP requires confirmation of the diagnostic histological, serological and radiological criteria, the involvement of other organs and a positive response to treatment with corticosteroids. Recently, three different diagnostic strategies for AIP have been proposed.