Abdominal aortic aneurysm as an IgG4-related disease.

The objectives of this study were to evaluate patients with aortic abdominal aneurysm (AAA) with regard to immunoglobulin (Ig)G4-related disease (IgG4-RD). IgG4-RD represents a recently defined condition comprised of a collection of disorders characterized by IgG4 hypergammaglobulinemia, the presence of IgG4-positive plasma cells in organs affected with fibrotic or sclerotizing changes and typical histopathological features. It was identified as a possible cause of vasculitis in large vessels. Studies have been published on a possible association between inflammatory aortic or cardiovascular disease and IgG4-RD. We examined 114 patients with AAA requiring surgery in order to identify findings which are characteristic of IgG4-RD. Aneurysm samples from seven patients showed histopathological features consistent with IgG4-RD and the presence of IgG4+ plasma cells. Only two of these seven patients showed elevated IgG4 serum levels higher 1·35 g/l. In five of the patients, the concentration of serum IgG4 was lower than 1·20 g/l, with the number of IgG4+ plasma cells being higher than 50/high-power field. These findings were consistent with AAA being a heterogeneous group of inflammatory diseases with different pathogenesis.