Autoimmune pancreatitis

A form of pancreatitis caused by the body's immune system attacking the pancreas

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis characterized by an autoimmune inflammatory process that affects the pancreas. It is part of a spectrum of autoimmune diseases and is often associated with other systemic autoimmune conditions.

Classification

Autoimmune pancreatitis is classified into two types:

• Type 1 AIP: Also known as lymphoplasmacytic sclerosing pancreatitis, this type is associated with IgG4-related disease. It is characterized by elevated serum IgG4 levels and the presence of IgG4-positive plasma cells in the pancreas.

• Type 2 AIP: Also known as idiopathic duct-centric pancreatitis, this type is not associated with IgG4-related disease. It is characterized by granulocytic epithelial lesions and is often associated with inflammatory bowel disease, such as ulcerative colitis.

Signs and symptoms

Patients with autoimmune pancreatitis may present with a variety of symptoms, including:

• Jaundice due to bile duct obstruction
• Abdominal pain
• Weight loss
• Diabetes mellitus
• Pancreatic insufficiency leading to steatorrhea

Diagnosis

The diagnosis of autoimmune pancreatitis is based on a combination of clinical, serological, radiological, and histological findings. Key diagnostic criteria include:

• Elevated serum IgG4 levels (particularly in Type 1 AIP)
• Characteristic imaging findings on CT scan or MRI, such as diffuse or focal pancreatic enlargement and a "sausage-shaped" pancreas
• Histological examination showing lymphoplasmacytic infiltration and fibrosis
• Response to corticosteroid therapy

Treatment

The primary treatment for autoimmune pancreatitis is corticosteroid therapy, which typically leads to rapid improvement in symptoms and imaging findings. In some cases, additional immunosuppressive agents such as azathioprine or mycophenolate mofetil may be used to maintain remission.

Prognosis

With appropriate treatment, the prognosis for autoimmune pancreatitis is generally good. However, relapses can occur, and long-term follow-up is necessary to monitor for recurrence and manage any associated autoimmune conditions.

Related pages

• Pancreatitis
• Chronic pancreatitis
• IgG4-related disease
• Autoimmune disease