What is microscopic angiitis?

• It is a necrotizing vasculitis that generally affects capillaries, as well as small arterioles and venules. • It is also called hypersensitivity vasculitis or leukocytoclastic vasculitis. • Unlike polyarteritis nodosa, all lesions of microscopic polyangiitis tend to be of the same age in any given patient and are distributed more widely. • The skin, mucous membranes, lungs, brain, heart, gastrointestinal tract, kidneys, and muscle can all be involved; necrotizing glomerulonephritis (90% of patients) and pulmonary capillaritis are particularly common.