What is the initial treatment for IgG4 (Immunoglobulin G4) pancreatitis?

From the Guidelines

The initial treatment for IgG4 pancreatitis is oral glucocorticoids, typically prednisone at a dose of 40 mg daily or 0.6-0.8 mg/kg daily for the first 4 weeks. This recommendation is based on the most recent and highest quality study available, which suggests that starting doses of 40 mg daily or 0.6-0.8 mg/kg daily for the first 4 weeks have been widely recommended in Japanese, American and European Guidelines 1.

Key Considerations

• The treatment should be continued for 2-4 weeks before gradually tapering the dose over 3-6 months.
• Most patients show rapid clinical improvement within 2-3 weeks, with resolution of symptoms, normalization of liver enzymes and pancreatic function, and reduction in pancreatic and biliary duct strictures.
• Glucocorticoids work by suppressing the underlying autoimmune inflammation characteristic of IgG4-related disease, reducing the infiltration of IgG4-positive plasma cells and lymphocytes in affected tissues.
• Before initiating treatment, it's essential to obtain baseline laboratory tests including liver function, pancreatic enzymes, and serum IgG4 levels.
• Patients should be monitored regularly during treatment to assess response and manage potential side effects of steroid therapy.

Alternative Treatment Options

• For patients who relapse after steroid tapering or who cannot tolerate steroids, immunomodulatory agents such as rituximab, azathioprine, or mycophenolate mofetil may be considered as steroid-sparing alternatives 1.
• UDCA may also be considered for its anticholestatic and anti-inflammatory effects, although its corticosteroid-sparing effects in IRC remain to be studied 1.

Important Notes

• The treatment of IgG4 pancreatitis should be individualized, taking into account the patient's overall health, disease severity, and potential contraindications for corticosteroid treatment.
• Patients with complex IgG4-SC and those with suspected malignancy should be referred to a specialist MDM for review 1.

From the Research

Initial Treatment for IgG4 Pancreatitis

• The initial treatment for IgG4 pancreatitis, also known as type 1 autoimmune pancreatitis (AIP), typically involves the use of systemic glucocorticoids 2.
• The recommended dose of oral prednisolone for induction of remission is 0.6 mg/kg/day, administered for 2-4 weeks, and then gradually tapered to a maintenance dose of 2.5-5 mg/day over a period of 2-3 months 2.
• Glucocorticoids are the cornerstone of treatment, and the indications for treatment are symptoms such as obstructive jaundice, abdominal pain, and involvement of extra-pancreatic digestive organs 3.
• The European Guideline on IgG4-related digestive disease recommends a weight-based treatment with glucocorticoids, initiated at a dose of 0.6-0.8 mg/kg body weight/day orally, for 1 month to induce remission, and then tapered within two additional months 3.

Response to Treatment and Maintenance

• The response to initial treatment should be assessed at week 2-4 with clinical, biochemical, and morphological markers 3.
• Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse 3.
• If the disease relapses during the 3 months of treatment, immunosuppressive drugs should be added 3.
• Rituximab, an anti-CD20 antibody, is effective in treating IgG4-related pancreato-biliary disease, especially in patients who have relapsed or are intolerant to glucocorticoids 4.

Diagnosis and Differential Diagnosis

• The diagnosis of IgG4 pancreatitis is based on a combination of typical radiological findings, elevation of serum IgG4 levels, histopathological findings, and response to steroids 2, 5.
• A comprehensive work-up with imaging, laboratory, and histological studies is required to achieve a diagnosis and rule out malignancies 6, 3.
• The differential diagnosis between type 1 and type 2 autoimmune pancreatitis is important, as they have different clinical features and treatment approaches 6.