Review of the diagnosis, classification and management of autoimmune pancreatitis

Table 1 The Mayo clinic HISORt criteria for the diagnosis of autoimmune pancreatitis

Category	Criteria
Histology	One of the following:
	Periductal lymphoplasmacytic infiltrate with obliterative phlebitis and storiform fibrosis (LPSP)
	Lymphoplasmacytic infiltrate with storiform fibrosis showing abundant IgG4 positive cells (> 10 cells/HPF)
Imaging (CT)/(MRI)	Typical; diffusely enlarged gland with diffuse rim enhancement, diffusely irregular attenuated pancreatic duct
	Other; focal pancreatic mass or enlargement; focal pancreatic duct stricture; pancreatic duct stricture, pancreatic atrophy; pancreatic calcification or pancreatitis
Serology	Elevated serum IgG4 level
Other organ involvement	Hilar/intrahepatic biliary strictures, persistent distal biliary strictures, parotid or lacrimal gland involvement, mediastinal lymphadenopathy or retroperitoneal fibrosis
Response to steroid therapy	Resolution/Marked improvement of pancreatic or extrapancreatic manifestion with steroid therapy

LPSP: Lymphoplasmacytic sclerosing pancreatitis; CT: Computed tomography; MRI: Magnetic resonance imaging; IgG4: Immunoglobulin G4; HPF: High powered field.

Table 2 International consensus diagnostic criteria for type 1 autoimmune pancreatitis

	Diagnosis of type 1 AIP
Diagnosis	Cardinal feature	Imaging evidence	Collateral evidence
Definitive type 1	Histology	Typical/inderminate	Confirmed LPSP
	Imaging	Typical Inderminate	Any level 1/2 ≥ 2 level 1
	Steroid response	Indeterminate	Level 1 S/OOI and Rt OR Level 1 D and level 2 S/OOI/H and Rt
Probable type 1		Indeterminate	Level 2 S/OOI/H and Rt

LPSP: Lymphoplasmacytic sclerosing pancreatitis; AIP: Autoimmune pancreatitis; S: Serology; OOI: Other organ involvement; Rt: Response to steroid therapy; H: Histology

Table 3 International consensus diagnostic criteria for type 2 autoimmune pancreatitis

	Diagnosis of type 2 AIP
Diagnosis	Imaging evidence	Collateral evidence
Definitive type 2	Typical/indeterminate	Histologically confirmed or clinical inflammatory bowel disease and level 2H and Rt
Probable type 2	Typical/indeterminate	Level 2 H/clinical inflammatory bowel disease and Rt

AIP: Autoimmune pancreatitis; Rt: Response to steroid therapy; H: Histology.

Table 4 International consensus diagnostic criteria level 1 and 2 criteria for type 1 and 2 autoimmune pancreatitis

	Type 1 AIP
Criterion	Level 1	Level 2
Parenchymal imaging	Typical: Diffuse enlargement with delayed enhancement	Indeterminate: Focal enlargement with delayed enhancement
Ductal imaging (ERP)	Long or multiple strictures (> 1/3 duct length) without upstream dilatation	Focal narrowing without upstream dilatation (< 5 mm)
Serology	IgG4 > 2x upper limit	IgG4 1-2x upper limit
Other organ involvement	Extrapancreatic organ histology. Any 3 of : 1 Lymphoplasmacytic infiltration with fibrosis and without granulocytic infiltration 2 Storiform fibrosis 3 Obliterative phlebitis 4 > 10 cells/HPF IgG4-positive cells Typical radiology. Any one of: 1 Segmental/multiple proximal or distal biliary stricture 2 Retroperitoneal fibrosis	Extrapancreatic organ histology including bile duct biopsies. Both of: 1 Marked lymphoplasmacytic infiltration without granulocytic infiltration 2 10 cells/HPF IgG4-positive cells Physical or radiological evidence of at least one of: 1 Enlarged salivary/lachrymal glands 2 Renal involvement
Histology of pancreas	LPSP and 3 of: 1 Periductal lymphoplasmacytic infiltrate without granulocytic infiltration 2 Obliterative phlebitis 3 Storiform fibrosis 4 > 10 cells/HPF IgG4-positive cells	LPSP and 2 of: 1 Periductal lymphoplasmacytic infiltrate without granulocytic infil tration 2 Obliterative phlebitis 3 Storiform fibrosis 4 > 10 cells/HPF IgG4-positive cells
Response to steroid (Rt)	Rapid (< 2 wk) radiological demonstration of marked improvement in pancreatic/extrapancreatic manifestations
Type 2 AIP
Parenchymal imaging	Typical: Diffuse enlargement with delayed enhancement	Indeterminate: Focal enlargement with delayed enhancement
Ductal Imaging (ERCP)	Long (> 1/3 duct length) or multiple strictures without upstream dilatation	Focal narrowing without marked upstream dilatation (< 5 mm)
Other organ involvement	Clinically diagnosed inflammatory bowel disease
Histology of pancreas	IDCP. Both of: 1 Granulocytic infiltration of duct wall with or without acinar inflammation 2 0-10 cells/HPF IgG4-positive cells	Both of : 1 Granulocytic and lymphoplasmacytic acinar infiltrate 2 0-10 cells/HPF IgG4-positive cells
Response to steroid (Rt)	Rapid (< 2 wk) radiological demonstration of marked improvement in manifestations

LPSP: Lymphoplasmacytic sclerosing pancreatitis; IDCP: Idiopathic duct-centric pancreatitis; AIP: Autoimmune pancreatitis; IgG4: immunoglobulin G4; ERP: Endoscopic retrograde pancreatography; Rt: Response to steroid therapy; HPF: High powered field.