[Classification of systemic vasculitides].

Several classifications of systemic vasculitides have been proposed: the Chapel Hill nomenclature, the classification criteria of the American College of Rheumatology and Lie's classification. All have their advantages and disadvantages. The role of ANCA (antineutrophil cytoplasmic antibodies) in classification of vasculitides is now accepted. The classification systems and the contribution of ANCA have led to better distinguishing vasculitis of medium calibre vessels from that involving small vessels, and in particular to distinguish between periarteritis nodosa and microscopic polyangiitis. Polyarteritis nodosa is characterised by involvement of medium calibre vessels (which can lead to vascular nephropathy or other ischemic organ involvement), whereas microscopic polyangiitis can be responsible, among other signs, for glomerulonephritis and pulmonary capillaritis.