Autoimmune
Pancreatitis
Epidemiology and Etiology:
- Middle age (range
10s to 70s)
- may be associated
with other autoimmune disorders:
- Sjogren syndrome
- PSC
- PBC
- IBD
- SLE
- DM
- Retroperitoneal fibrosis
Common sites:
Gross features:
- firm enlargement of
the pancreas
- diffuse,
localized, or multifocal
- may be centered in
the head
- irregular stenosis
of the pancreatic ductal system
Histologic features:
- chronic pancreatitis
- dense duct-centric
inflammation (main and medium-sized to large interlobular ducts)
- lymphocytic or lymphoplasmacytic
- with or
without lymphoid follicle formation
- T cell
predominance (CD4/CD8)
- not
monoclonal (as in lymphoma)
- May be unevenly
distributed
- May see
eosinophils, neutrophils, macrophages, dendritic cells
- expansion of
periductal fibrous tissue containing numerous inflammatory cells
- acini and islets
may be affected
- reactive or
degenerative ductal epithelial changes
- extensive fibrosis
in advanced cases
- periductal
- perilobular >
intralobular
- peripancreatic
soft tissues
- periphlebitis often
of small to medium sized veins
- may involve the
portal vein
- may see frank
vasculitis
- interstitial
fibroblastic proliferation with storiform architecture (“inflammatory
pseudotumour-like”)
- not normally seen
(in contrast to alcoholic):
- calcification
- fat necrosis
- protein plugging
- psuedocyst
formation
Immunophenotype:
Marker:
|
Sensitivity:
|
Specificity:
|
|
|
|
Molecular features:
- DRB1*0405-DQB1*0401
haplotype associated
Other features:
- Overlap with
nonalcoholic duct destructive chronic pancreatitis and lymphoplasmacytic
sclerosing pancreatitis
- radiology
- ERCP – may see
segmental or diffuse narrowing of the main pancreatic duct
- May see
Sclerosing changes of extrapancreatic bile ducts similar to PSC
- mimics carcinoma
with a capsule-like rim
- bloodwork:
- autoantibodies
(most)
- ANA
- Antilactoferrin
(ALF)
- Anticarbonic
anhydrase II (ACA-II)
- Rheumatoid
factor
- Anti-alpha-fodrin
- RARELY
antimitochondrial (M2) (elevated in PBC
- USUALLY
NOT Antineutrophil cytoplasmic autoantibodies (ANCAs)
- hypergammaglobulinemia
(IgG4)
- eosinophilia
- complications:
- diabetes mellitus
- obstructive jaundice
(rarely occurs in other types of pancreatitis
- considered
reversible with steroids (and DM is reversible as well)
- some patients
improve spontaneously with no treatment
References:
- Sternberg 2004
- Essentials
of AP 2006
- Odze 2004