REVIEW ARTICLE A novel clinical entity, IgG4-related disease (IgG4RD): general concept and details

Abstract IgG4-related disease (IgG4RD) is a novel clinical disease entity characterized by elevated serum IgG4 concen-tration and tumefaction or tissue infiltration by IgG4-positive plasma cells. IgG4RD may be present in a certain proportion of patients with a wide variety of diseases, including Miku-licz’s disease, autoimmune pancreatitis, hypophysitis, Riedel thyroiditis, interstitial pneumonitis, interstitial nephritis, prostatitis, lymphadenopathy, retroperitoneal fibrosis, inflammatory aortic aneurysm, and inflammatory pseudotu-mor. Although IgG4RD forms a distinct, clinically indepen-dent disease category and is attracting strong attention as a new clinical entity, many questions and problems still remain to be elucidated, including its pathogenesis, the establishment of diagnostic criteria, and the role of IgG4. Here we describe the concept of IgG4RD and up-to-date information on thi