The antineutrophil cytoplasmic antibody–associated vasculitides

Wegenerʹs granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome are small- to medium-vessel vasculitides linked by overlapping pathology and the presence of antineutrophil cytoplasmic antibodies (ANCA). Commonly referred to as the ANCA-associated vasculitides, these diseases are challenging to diagnose and to treat. Distinguishing the ANCA-associated vasculitides from other forms of vasculitis or nonvasculitic processes (such as infection) can be particularly difficult. This review describes the clinical and pathologic hallmarks of the ANCA-associated vasculitides, discusses the role of ANCA assays in diagnosis and treatment, and outlines an approach to the evaluation and management of these diseases.