Diagnostic Criteria of Autoimmune Pancreatitis


Diagnosis

Primary basis for diagnosis

Imaging evidence

Collateral evidence

Definitive type 1 AIP

Histology

Typical/indeterminate

Histologically confirmed LPSP

Imaging

Typical

Any non-D level 1/level 2

Indeterminate

Two or more from level 1 (+level 2 D*)

Response to steroid

Indeterminate

Level 1 S/OOI + Rt or level 1 D + level2 S/OOI/H + Rt

Probable type 1 AIP
 
Indeterminate

Level 2 S/OOI/H + Rt


*Level 2 D is counted as level 1 in this setting, Rt response to steroid, D pancreatic duct findings, S serum findings, OOI other organ involvement, LPSP lymphoplasmacytic sclerosing pancreatitis, AIP autoimmune pancreatitis, H histological findings




Table 7.2
Level 1 and level 2 criteria for type 1 AIP






























































































 
Criterion
Level 1
Level 2

P
Parenchymal imaging
Typical

Indeterminate (including atypical b)

Diffuse enlargement with delayed enhancement (sometimes associated with rim-like enhancement)
Segmental/focal enlargement with delayed enhancement

D
Ductal imaging (ERP)
Long (>1/3 length of the mpd) or multiple strictures without marked upstream dilatation
Segmental/focal narrowing without marked upstream dilatation (duct size <5 mm)

S
Serology
IgG4 >2 X upper limit of normal value
IgG4 1–2 X upper limit of normal value

OOI
Other organ involvement
(a) or (b)
(a) or (b)

(a) Histology of extrapancreatic organs

(a) Histology of extrapancreatic organs including endoscopic biopsies of bile duct c

Any three of the following:
Both of the following:

 (i) Marked lymphoplasmacytic
 (i) Marked lymphoplasmacytic infiltration without granulocytic infiltration

 (ii) Infiltration with fibrosis and without granulocytic infiltration
 (ii) Abundant (>10 cells/hpf) IgG4-positive cells

 (iii) Storiform fibrosis
  

 (iv) Obliterative phlebitis
  

 (v) Abundant (>10 cells/hpf) IgG4-positive cells
  

(b) Typical radiological evidence

(b) Physical or radiological evidence

At least one
At least one

 (i) Segmental/multiple proximal (hilar/intrahepatic) or proximal and distal bile duct stricture
 (i) Symmetrically enlarged salivary/lacrimal glands

 (ii) Retroperitoneal fibrosis
 (ii) Radiologic evidence of renal involvement described in association with AIP

H
Histology of the pancreas
LPSP (core biopsy/resection)
LPSP (core biopsy)

At least three of the following:
Any two of the following:

 (i) Periductal lymphoplasmacytic infiltrate without granulocytic infiltration
 (i) Periductal lymphoplasmacytic infiltrate without granulocytic infiltration

 (ii) Obliterative phlebitis
 (ii) Obliterative phlebitis

 (iii) Storiform fibrosis
 (iii) Storiform fibrosis

 (iv) Abundant (>10 cells/hpf) IgG4-positive cells
 (iv) Abundant (>10 cells/hpf) IgG4-positive cells

Diagnostic steroid trial

Response to steroid (Rt)a

Rapid (≤2 weeks) radiologically demonstrable resolution or marked improvement in pancreatic/extrapancreatic manifestations


aDiagnostic steroid trial should be conducted carefully by pancreatologists with caveats (see text) only after negative work-up for cancer including EUS-FNA

bAtypical: some AIP cases may show low-density mass, pancreatic ductal dilatation, or distal atrophy. Such atypical imaging findings in patients with obstructive jaundice and/or pancreatic mass are highly suggestive of pancreatic cancer. Such patients should be managed as pancreatic cancer unless there is strong collateral evidence for AIP and a thorough work-up for cancer is negative (see algorithm)

cEndoscopic biopsy of duodenal papilla is a useful adjunctive method because the ampulla is often involved pathologically in AIP




Type 2 AIP


The cardinal histological finding of type 2 AIP is GEL, which is necessary for the diagnosis of definitive type 2 AIP. If the examination of biopsy tissue specimens or pancreatic tissues provides confirmation of GEL, that is, if the major histological findings suggesting type 2 AIP indicate a level 1 finding, definitive type 2 AIP can be diagnosed. Cases that show typical pancreatic imaging findings of AIP with inflammatory bowel disease and responsiveness to steroid therapy can be diagnosed as probable type 2 AIP, even in the absence of the histological finding of GEL. However, it is essential to continue clarifying the pathogenesis of type 2 AIP because of its unknown etiology (Tables 7.3 and 7.4).


Table 7.3
Diagnosis of definitive and probable type 2 AIP using the International Consensus Diagnostic Criteria (ICDC)




















Diagnosis
Imaging evidence
Collateral evidence

Definitive type 2 AIP
Typical/indeterminate
Histologically confirmed IDCP or clinical IBD + level 2 H + Rt

Probable type 2 AIP
Typical/indeterminate
Level 2 H/clinical IBD + Rt


Rt response to steroid, IBD inflammatory bowel disease, IDCP idiopathic duct-centric chronic pancreatitis, AIP autoimmune pancreatitis, H histological findings



Table 7.4
Level 1 and level 2 criteria for type 2 AIP


















































 
Criterion
Level 1
Level 2

P
Parenchymal imaging
Typical

Indeterminate (including atypical b)

Diffuse enlargement with delayedenhancement (sometimes associatedwith rim-like enhancement)
Segmental/focal enlargement with delayedenhancement

D
Ductal imaging (ERP)
Long (>1/3 length of the mpd) ormultiple strictures without markedupstream dilatation
Segmental/focal narrowing without markedupstream dilatation (duct size <5 mm)

OOI
Other organ involvement
  
Clinically diagnosed inflammatorybowel disease

H
Histology of the pancreas(core biopsy/resection)
IDCP
  

Both of the following:
Both of the following:

 (i) Granulocytic infiltration of duct wall(GEL) with or without granulocyticacinar inflammation
 (i) Granulocytic and lymphoplasmacyticacinar infiltrate

 (ii) Absent or scant (0–10 cells/hpf)IgG4-positive cells
 (ii) Absent or scant (0–10 cells/hpf)IgG4-positive cells

Diagnostic steroid trial

Response to steroid (Rt)a

Rapid (<2 weeks) resolution or marked improvement in manifestations


aDiagnostic steroid trial should be conducted carefully by pancreatologists with caveats (see text) only after negative work-up for cancer including EUS-FNA

bAtypical: some AIP cases may show low-density mass, pancreatic ductal dilatation, or distal atrophy. Such atypical imaging findings in patients with obstructive jaundice and/or pancreatic mass are highly suggestive of pancreatic cancer. Such patients should be managed as pancreatic cancer unless there is strong collateral evidence for AIP and a thorough work-up for cancer is negative (see algorithm)


AIP-Not Otherwise Specified (NOS)


Cases that exhibit compatible pancreatic imaging findings, without other cardinal factors of type 1 or 2 AIP, and show responsiveness to steroid treatment can be diagnosed as AIP-not otherwise specified (NOS). These cases should be carefully followed up, while considering the possibility of other diseases (Table 7.5).


Table 7.5
Diagnosis of AIP-not otherwise specified using the International Consensus Diagnostic Criteria (ICDC)

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Related posts:

  1. Tissue Acquisition for Histologic Diagnosis
  2. Serology
  3. Development to Chronic Pancreatitis
  4. IgG4-Related Sclerosing Cholangitis

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Jun 3, 2017 | Posted by in GENERAL SURGERY | Comments Off on Diagnostic Criteria of Autoimmune Pancreatitis

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