Small vessel vasculitides

Following the 2012 Chapel Hill Consensus Conference, small vessel vasculitides have recently been recategorized into two major groups. The first comprises antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides, which are pauci-immune, with minimal immune deposits in vessel walls. ANCA-associated vasculitides are the most common cause of rapidly progressive glomerulonephritis. The second group comprises immune complex vasculitides, associated with immune complex deposition in the vasculature, including antiglomerular basement membrane disease, IgA vasculitis (Henoch-Schönlein purpura) and vasculitides secondary to systemic immune complex diseases such as systemic lupus erythematosus, dysproteinaemias, cryoglobulinaemias and chronic infections. This article describes recent advances in understanding of the pathogenesis of these conditions and reviews common presentations. Consideration is given to recent clinical trials in the management of ANCA-associated vasculitides.