From the Guidelines
Autoimmune pancreatitis should be treated with corticosteroids as first-line therapy, usually starting with prednisone at 40mg daily for 2-4 weeks, followed by a gradual taper over 3-6 months, as this approach has been shown to be effective in managing the condition and improving patient outcomes. The diagnosis of autoimmune pancreatitis is based on a combination of imaging findings, elevated serum IgG4 levels, and histopathology showing lymphoplasmacytic infiltration with IgG4-positive cells 1.
Key Considerations
- Autoimmune pancreatitis is a rare chronic inflammatory disorder of the pancreas caused by an autoimmune process, and it can present with clinical and radiologic characteristics similar to those of pancreatic cancer, such as jaundice, weight loss, and an elevated CA 19-9 level 1.
- Increased serum immunoglobulin (Ig) G levels support a diagnosis of autoimmune pancreatitis, although an elevated serum IgG4 level is the most sensitive and specific laboratory indicator 1.
- The classic appearance of the pancreas on abdominal CT in patients with diffuse pancreatic involvement is a sausage-shaped enlargement of the organ surrounded by a capsule-like peripheral rim, although focal enlargement of the pancreas is observed in some cases 1.
Treatment Approach
- For maintenance therapy in patients with relapsing disease, immunomodulators like azathioprine (2mg/kg/day), 6-mercaptopurine (1-1.5mg/kg/day), or mycophenolate mofetil (1000-1500mg twice daily) may be used 1.
- Rituximab (375mg/m² weekly for 4 weeks) can be considered for steroid-resistant cases.
- Regular monitoring of pancreatic function is important as some patients may develop exocrine or endocrine insufficiency requiring enzyme replacement or diabetes management.
Diagnostic Criteria
- A diagnosis of autoimmune pancreatitis can be made based on a combination of imaging findings, elevated serum IgG4 levels, and histopathology showing lymphoplasmacytic infiltration with IgG4-positive cells 1.
- The European Association for the Study of the Liver (EASL) clinical practice guidelines recommend that the diagnosis of autoimmune pancreatitis be made in patients with cholangiographic findings typical of sclerosing cholangitis on the basis of histological features of autoimmune pancreatitis or classical imaging findings of autoimmune pancreatitis and elevated IgG4 1.
From the Research
Definition and Classification of Autoimmune Pancreatitis
- Autoimmune pancreatitis (AIP) is a rare disease that can be classified into two distinct types: type 1 (AIP-1) and type 2 (AIP-2) 2, 3, 4.
- AIP-1 is considered a pancreatic manifestation of multiorgan disease related to IgG4, while AIP-2 is considered a pancreas-specific disease not related to IgG4 2, 3.
Diagnosis of Autoimmune Pancreatitis
- The diagnosis of AIP should be made by a comprehensive evaluation of clinical, radiological, serological, and pathological findings 2.
- The steroid response can be confirmed on clinical images and is included as an optional diagnostic item of AIP 4.
Treatment of Autoimmune Pancreatitis
- The standard therapy for AIP is oral administration of corticosteroids, with an initial prednisolone dose of 0.6 mg/kg/day recommended 5.
- Maintenance treatment with low-dose steroid reduces but does not eliminate relapses, and immunomodulators or rituximab may be required to maintain remission in some patients, especially those with type 1 AIP 2, 3, 6, 5.
- Steroid treatment results in normalization of serological markers, including IgG4, but may induce adverse events such as chronic glycometabolism, obesity, and osteoporosis 4.