[IgG4-related disease is a rare differential diagnosis of malignant and autoimmune diseases]

Immunoglobulin G4-related disease (IgG4-RD) is an inflammatory and fibrotic disease with the potential to produce diffuse enlargement, massforming lesions or stenoses in a wide range of organs. Elevation of serum IgG4 concentration and high levels of IgG4-positive cells in the inflamed tissue are common denominators. Type 1 autoimmune pancreatitis is one of the main manifestations, and its recognition preceded the definition of IgG4-RD as a novel clinical entity. The aetiology, pathophysiology, epidemiology and clinical long-term outcome of IgG4-RD are not fully elucidated. Steroids are effective in most patients, sometimes combined with other antiinflammatory drugs.