Names and definitions of vasculitis adopted by the Chapel Hill Consensus Conference on the nomenclature of systemic vasculitis

1. Polyarteritis nodosa (PAN): Necrotizing inflammation of medium-sized or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries or venules.
2. Wegener´s granulomatosis (WG): Granulomatous inflammation involving the respiratory tract, and necrotizing vasculitis affecting small to medium-sized vessels, e. g. capillaries, venules, arterioles and arteries. Necrotizing glomerulonephritis is common.
3. Churg-Strauss syndrome (CSS): Eosinophil-rich and granulomatous inflammation involving the respiratory tract and necrotizing vasculitis affecting small to medium-sized vessels, and associated with asthma and blood eosinophilia.
4. Microscopic polyangiitis (MSA): Necrotizing vasculitis with few or no immune deposits affecting small vessels, i.e. capillaries, venules or arterioles. Necrotizing arteritis of small and medium-sized arteries may be present. Necrotizing glomerulonephritis is very common. Pulmonary capillaritis often occurs.