ANCA-associated small-vessel vasculitis.

Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis is the most common primary systemic small-vessel vasculitis to occur in adults. Although the etiology is not always known, the incidence of vasculitis is increasing, and the diagnosis and management of patients may be challenging because of its relative infrequency, changing nomenclature, and variability of clinical expression. Advances in clinical management have been achieved during the past few years, and many ongoing studies are pending. Vasculitis may affect the large, medium, or small blood vessels. Small-vessel vasculitis may be further classified as ANCA-associated or non-ANCA-associated vasculitis. ANCA-associated small-vessel vasculitis includes microscopic polyangiitis, Wegener's granulomatosis, Churg-Strauss syndrome, and drug-induced vasculitis. Better definition criteria and advancement in the technologies make these diagnoses increasingly common. Features that may aid in defining the specific type of vasculitic disorder include the type of organ involvement, presence and type of ANCA (myeloperoxidase-ANCA or proteinase 3-ANCA), presence of serum cryoglobulins, and the presence of evidence for granulomatous inflammation. Family physicians should be familiar with this group of vasculitic disorders to reach a prompt diagnosis and initiate treatment to prevent end-organ damage. Treatment usually includes corticosteroid and immunosuppressive therapy.