Asian Diagnostic Criteria for AIP 2008
In 2008, a group of Japanese and Korean investigators came up with consensus criteria for diagnosing AIP.
Criterion I: Imaging
Both of the following criteria are required:
Imaging of the pancreatic parenchyma: diffuse/segmental/focal enlargement of the gland, occasionally with a mass and/or hypoattenuation rim
Imaging of the pancreaticobiliary ducts: diffuse/segmental/focal pancreatic duct narrowing often with stenosis of the bile duct
Criterion II: Serology
One of the following criteria are required:
High levels of serum IgG or IgG4
Detection of autoantibodies
Criterion III: Histopathology of Pancreatic Biopsy Lesion
Lymphoplasmacytic infiltration with fibrosis and abundant IgG4-positive cell infiltration
Autoimmune pancreatitis could be diagnosed in the presences of criterion I in addition to one of the criterion II or by criterion III alone. The authors of these criteria also proposed an optional criterion (response to steroids). In the presence of criteria I alone, a diagnostic trial of steroid therapy could be conducted carefully by pancreatologist after a negative work-up for cancer.
The major points of agreement between the two criteria are that the radiological appearance of a diffusely enlarged pancreas with a low-density rim and delayed enhancement is highly suggestive of AIP. The criteria also agree that the histological appearance of a LPSP is diagnostic of AIP; however, in the Asian criteria this finding can be used to diagnose AIP only in resection specimens and in both resection and core biopsies in HISORt criteria. There is also consensus that, in specific instances, a trial of steroids can be tried after a negative work-up for cancer, and this can be diagnostic in it own regard. In fact, Kim et al. reported that a trial of corticosteroids was useful in differentiating seronegative AIP from pancreatic cancer based on the improvement in duct narrowing 2 weeks after initiation of corticosteroid therapy.
While the Asian and HISORt criteria agree on a number issues, there are also disagreements on some critical issues. Consensus meetings have significantly narrowed, but not eliminated, differences. The major points of contention are that the Asian criteria mandate the use of an ERCP in all case of AIP, whereas the HISORt does not. This reflects practice patterns in North America, where diagnostic ERPs are rarely performed. In addition, the lack of dilatation of pancreatic duct, a key feature of AIP to distinguish from cancer, can often be inferred from high resolution CT or MRI.
The Asian serologic criteria are met if there are elevated titers of either serum IgG, IgG4 or autoantibodies (e.g., antinuclear antibody, rheumatoid factor, antilactoferrin, anticarbonic anhydrase 2). Owing to the nonspecificity of this combined panel, the HISORt serologic criteria use only the single best marker of AIP, specifically, serum IgG4. Of note, autoantibodies are not part of the HISORt criteria. They also have differing points of view on incorporating other organ involvement in the AIP work-up.
Expert Rev Gastroenterol Hepatol. 2009;3(2):197-204. © 2009 Expert Reviews, Ltd.
Cite this: Autoimmune Pancreatitis: An Update - Medscape - Apr 01, 2009.