ANCA-associated vasculitis

Abstract The ANCA-associated vasculitides (AAV) are a grouping of three syndromes of acute and chronic inflammation characterized by their clinical and histological phenotypes, which are associated with circulating antineutrophil cytoplasm autoantibodies (ANCA). They comprise: granulomatosis with polyangiitis (GPA, formerly Wegener’s granulomatosis); microscopic polyangiitis (MPA); and eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome). The defining histological lesion is a microscopic vasculitis affecting arterioles, capillaries, or venules associated with few or no deposits of immunoglobulin or complement. Granulomata, involving or close by blood vessels, are commonly present in GPA. These diseases involve multiple organ systems with considerable heterogeneity in extent and severity of organ involvement between patients, and overlapping clinical and histological features between syndromes.