Last Updated on January 8, 2021
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 |
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:
References:
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Dr. Amar Udare, MD, DNB
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.
