Copyright ©The Author(s) 2024.
World J Gastroenterol. Feb 28, 2024; 30(8): 817-832
Published online Feb 28, 2024. doi: 10.3748/wjg.v30.i8.817
Table 1 Differential characteristics between type 1 and type 2 autoimmune pancreatitis

Gender (M:F)3:11:1
Mean age at disease onset60-70 yr40-60 yr
EpidemiologyAsia > Western CountriesWestern Countries > Asia
Main clinical manifestationsPainless jaundice (75%); Abdominal symptoms (40%)Abdominal pain and acute pancreatitis (50%)
Weight loss
Diabetes and exocrine pancreatic insufficiency
Extrapancreatic manifestationsIgG4-related disease extrapancreatic manifestations (50%)IBD (49%-67%)
Hepatobiliary disease
Retroperitoneal fibrosis and/or aortitis
Head and neck involvement
Mikulicz syndrome
Serum IgG4 levelsElevated (circulating IgG4 to IgG levels typically > 10%) (50%)Normal (p-ANCA and c-ANCA autoantibodies often positive)
Histologic featuresLymphoplasmacytic infiltrates rich in IgG4+ plasma cellsGranulocytic epithelial lesions
Storiform fibrosis
Obliterative phlebitis
Steroid therapyResponsiveResponsive
RelapseHigh rate (39%)Rare
Table 2 Main radiological features of autoimmune pancreatitis
CT scanDiffuse or focal sausage-like swelling
Cut-tail sign
Homogeneous reduced enhancement with dotted contrast enhancements of normal parenchyma
Hypo-enhanced capsule-like rim with delayed enhancement
Thickened hyperdense MPD walls
MRIDiffuse or focal lower intensity signal on T1-weighted MRI images, with an even more hypointense capsule-rim
Moderately higher intensity signal on T2-weighted images, still with a low-intensity fibrotic rim
DWI homogeneously hyperintensity
MRCPMultiple and long MPD skip narrowings
No upstream dilatation
Side PD branches (icicle sign)
Duct-penetrating sign, in case of mass-forming AIP
18F-FDG PET-CTDiffused or focal increased uptake
EUSDiffuse pancreatic enlargement, with echopoor echotexture, loss of interface with the splenic vein, concomitant intraparenchymal hyperechoic foci and strands
Hyperechoic MPD walls
Solitary, irregular, hypoechoic mass, in case of mass-forming AIP, generally in the head of the pancreas, without upstream dilatation of the MPD
ElastographyMagnified parenchymal stiffness