The natural course of autoimmune pancreatitis

Since autoimmune pancreatitis (AIP) responds dramatically to steroid therapy, most AIP patients are promptly treated with steroids when the diagnosis of AIP is made. Therefore, the natural course of AIP is unclear. This study aimed to evaluate the clinical course of AIP patients without steroid therapy and assess the indications for steroid therapy in these patients.

Clinical features were retrospectively assessed in 12 patients who were followed for more than 6 months after the diagnosis of AIP without steroids.

Six patients were later treated with steroids due to exacerbation of AIP. Five of them developed obstructive jaundice due to bile duct stenosis. Segmental enlargement progressed to diffuse enlargement in 4 patients. Serum IgG and/or IgG4 levels increased with AIP progression. In 4 patients, swelling of the salivary glands preceded AIP. Radiological and clinical features responded well to steroid therapy. Spontaneous improvement occurred in 3 patients. Four asymptomatic patients with segmental pancreatic enlargement have demonstrated no changes without steroid therapy until now.

About half of the segmental AIP cases progressed and needed steroid therapy, which was effective. Asymptomatic segmental AIP cases without biliary lesions may be followed without steroid therapy with periodic laboratory and imaging studies.