Abstract
Autoimmune pancreatitis is currently diagnosed in accordance with the Japan Pancreas Society diagnostic criteria for the condition. The diagnostic criteria require confirmation of irregular narrowing of the main pancreatic duct and enlargement of the pancreas. Assessment of pancreatic duct narrowing is therefore the most important part of diagnosing the condition. Pancreatic duct narrowing is usually diagnosed from images of the pancreatic duct on endoscopic retrograde cholangiopancreatography. It is generally agreed that the pancreatic duct is narrowed if "the diameter of the main pancreatic duct is smaller (narrower) than the normal portion of the duct, the walls are irregular, and such abnormalities are seen along a certain length of the duct (at least one-third of the extreme length of the pancreas according to the current diagnostic criteria). It is important to differentiate between pancreatic duct narrowing and pancreatic duct stenosis. Specifying that there must be narrowing of at least one-third of the length of the pancreatic duct prevents confusion with pancreatic cancer. There are still problems with the diagnosis of autoimmune pancreatitis with regard to the relationship with mass-forming pancreatitis and dealing with patients who test negative for autoantibodies and patients in whom only the pancreatic duct findings do not meet the diagnostic criteria. It should be recognized that the current diagnostic criteria deal with autoimmune pancreatitis with pancreatic duct narrowing (duct-narrowing autoimmune pancreatitis) rather than autoimmune pancreatitis in the broader sense of the term.
