The Primary Vasculitides

Primary vasculitis is the inflammation and necrosis of vessel walls not associated with infections, drugs, and autoimmune and lymphoproliferative disorders. It is important to make the correct diagnosis of different types of vasculitis, as their prognosis may be significantly different. Classification of vasculitis based on the size of the vessel is helpful, but there is often an overlap. Whereas the criteria proposed by the American College of Rheumatology are primarily clinical, the definitions set forth by the Chapel Hill Consensus Conference are based only on histologic observations. Correct diagnosis requires appropriate incorporation of the clinical history, laboratory parameters, and the histologic data. Incorporation of antineutrophil cytoplasmic antibodies in defining the pathogenesis of vasculitis has been particularly useful in diagnosing those small vessel vasculitides that are life threatening and need immediate intervention.