Autoimmune pancreatitis (diagnostic criteria)

Last revised by Henry Knipe on 13 Jul 2022

There are several sets of diagnostic criteria for autoimmune pancreatitis (AIP), with some overlap and contradictions.

Several different sets of diagnostic criteria are in use 4.

  • both criteria I to be fulfilled
  • one criterion II
  • consistent histology

The criteria are 1:

  • criteria I: imaging
    • enlargement of the gland (may be diffuse/segmental/focal) +/- hypoattenuating rim (halo)
    • pancreatic duct narrowing (may be diffuse/segmental/focal) +/- stenosis of the common bile duct
  • criteria II: serology
    • elevated serum IgG or IgG4
    • detectable autoantibodies (ANA, RF)
  • criteria III: histopathology
    • lymphoplasmacytic infiltration (IgG4 positive) with fibrosis 

AIP should be suspected in patients with obstructive jaundice, pancreatic mass/enlargement, or pancreatitis, AND one or more of five cardinal features of AIP in 2

  • histology
  • imaging
  • serology
  • other organ involvement
  • response to steroid therapy 

Summarized by the mnemonic HISORt.

Typical histological features include lymphoplasmacytic infiltrate, storiform fibrosis (elevated IgG4), and obliterative phlebitis.

Classical imaging features of AIP.

Unlike the Asian criteria, the Mayo Clinic criteria take account of possible other organ involvement accompanying AIP in the setting of IgG4-related sclerosing disease, and also of the response to steroid therapy following which normalization of imaging and histological findings is expected.

In 2010, during the 14th Congress of the International Association of Pancreatology, criteria were proposed as a consensus of the working group 3,4. These are the same as the five Mayo Clinic 2 features as listed above with response to steroids being optional. Levels 1 and 2 have been introduced based on the diagnostic reliability of each feature. For example, if IgG4 elevation is more than 2, it is considered level 1 and if it is less than 2, it is considered level 2.

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 2: typical AIP histology
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  • Case 4
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