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IgG4 Autoimmune Pancreatitis and associated anomalies

Last Updated on January 8, 2021

Sausage shaped pancreas with a hypo-attenuating halo suggestive of autoimmune pancreatitis.
Sausage shaped pancreas with a hypo-attenuating halo suggestive of autoimmune pancreatitis.

What is an IgG4 Autoimmune Pancreatitis ?

Auto-immune pancreatitis is a chronic immune-mediated fibroinflammatory disease primarily involving pancreas responding to steroid therapy.

What are the diagnostic criteria for autoimmune IgG4 pancreatitis?

The Mayo Clinic HISORt Criteria are used for confirming the diagnosis. Here are the details:

Mayo Clinic HISORt Criteria for IgG4 Autoimmune Pancreatitis

Histology:

(1) Periductal lymphoplasmacytic infiltrate with obliterative phlebitis and storiform fibrosis (LPSP) OR

(2) Lymphoplasmacytic infiltrate with storiform fibrosis showing abundant (210 cells/HPF) IgG4-positive cells

Imaging:

Typical: diffusely enlarged gland with delayed (rim) enhancement; diffusely irregular, attenuated main pancreatic duct

Others: Focal pancreatic mass/enlargement; focal pancreatic duct stricture; pancreatic atrophy; pancreatic calcification; or pancreatitis

Serology: Elevated serum IgG4 level (>135 mg/dL)

Other Organ Involvement.

Response to steroids.

What are the two subtypes of autoimmune pancreatitis?

Type 1 (lymphoplasmacytic sclerosing pancreatitis) and type 2 (idiopathic duct-centric chronic pancreatitis).

  • Type 1 autoimmune pancreatitis is the pancreatic manifestation of IgG4-related disease.
  • Type 2 has a distinctly different histologic and clinical profile, with no elevation of serum IgG4 concentrations or presence of autoantibodies.
AIP type 1 AIP type 2
Geographical distribution Asia > United States, Europe Europe > United States > Asia
Age at presentation 60-70 s 40-50 s
Gender Male >> Female Male = Female
Symptoms Jaundice, Abdominal pain Jaundice, Abdominal pain
Serology IgG4, IgG,
Autoantibodies
Usually negative
Pancreatic images Enlarged
(focal, diffuse)
Enlarged
(focal, diffuse)
Pancreatic histology Lymphoplasmacytic sclerosing Idiopathic duct-centritic pancreatitis with
granulocyte epithelial lesion.
Extrapancreatic
lesions
Sclerosing cholangitis,
sialoadenitis,
retroperitoneal fibrosis,
interstitional nephritis,
Inflammatory bowel
disease
Steroid response Excellent Excellent
RRelapse High Rare
Type 1 IgG4 vs type 2 Autoimmune Pancreatitis

What are the other anomalies associated with IgG4 Pancreatitis?

IgG4 disease is a multi-system disorder. Following disorders have been described (Common disorders are highlighted):

  • CNS:
    • Hypertrophic pachymeningitis
    • Autoimmune hypophysitis
    • Orbital pseudotumor
  • Salviay / lacrimal glands:
    • Mikulicz’s disease
    • Kuttner’s tumor
  • Thyroid
    • Riedel’s thyroiditis
    • Hashimoto’s thyroiditis
  • Lungs
    • Pulmonary pseudotumor
    • Interstitial pneumoniaLymphadenopathy
  • Hepatobiliary:
    • Autoimmune pancreatitis
    • Sclerosing cholangitis
    • Liver pseudotumor
  • Retroperitoneal fibrosis
  • Tubulointerstitial nephritis
  • Inflammatory aortic aneurysm
  • Prostatitis, testicular involvement
  • Cutaneous pseudolymphoma

What is the management for IgG4 Autoimmune Pancreatitis?

IgG4 pancreatitis responds well to corticosteroids.

Detailed discussion with video:

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References:

  1. Head to toe IgG4 Autoimmune Pancreatitis
  2. Grainger & Allison’s Diagnostic Radiology

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About the author

Dr. Amar Udare, MD, DNB

Dr Amar Udare Dr. Amar Udare is a board-certified radiologist. He is currently working as a fellow radiologist at McMaster University, Canada. He has a passion for teaching (#FOAMrad and #FOAMed) and has been a semi-finalist for the 2018 and 2020 Aunt-Minnie Most effective Radiology Educator Awards. He has authored multiple peer-reviewed publications which can be accessed on PubMed and Google Scholar.

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IgG4 Autoimmune Pancreatitis and associated anomalies

by Dr. Amar Udare, MD time to read: 2 min
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