Review of the diagnosis, classification and management of autoimmune pancreatitis

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.