Vasculitis is the term used to describe a large group of clinically heterogeneous disorders associated with inflammation of the blood vessels. The exact cause of vasculitis is unknown, although pathogenesis in most cases is assumed to be largely autoimmune; inflammation of the blood vessels can also result from infection, drug-exposure or other diseases. Vasculitis—encompassing large, medium and small-vessel vasculitides—affects people of all ages and races, and both sexes, although most types differ in whom they affect and the organs that are involved. Patients with vasculitis are traditionally treated with steroids, but several new drugs are in development, or have recently become available, that show promise. Vasculitis can be life-threatening but, owing to advances in treatment approaches, patients usually respond well to treatment and can make a full recovery.

The progress in the field of vasculitis over the past 25 years, as outlined in this Focus issue, shows what can be achieved when researchers work together across the world. The five specially commissioned Reviews and one Perspectives article outline the latest research in this field, covering vasculature development, the pathogenesis of vasculitis highlighting the role of anti-neutrophil cytoplasmic autoantibodies (ANCA) and eosinophils, current and emerging techniques for ANCA detection, clinical approaches to treat patients with ANCA-associated vasculitis, and issues relating to the design of clinical trials in this heterogeneous group of uncommon disorders.

The Reviews in this Focus on vasculitis have been made freely available online for 6 months thanks to support from Genentech, a member of the Roche group.