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
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 |
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 |
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 |
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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