Classification of vasculitis.

Usually classifications of vasculitic syndromes are based on clinical and histopathologic findings because pathogenetic mechanisms are poorly understood. A subcommittee of the Diagnostic and Therapeutic Criteria Committee of the American College of Rheumatology recently developed classification criteria for seven major vasculitic disorders through the analysis of prospectively collected patient data from 48 centers. Using two classification methods, the subcommittee derived criteria for polyareritis nodosa, Churg-Strauss syndrome, Wegner's granulomatosis, hypersensitivity vasculitis, Henoch-Schönlein purpura, giant cell (temporal) arteritis, and Takayasu's arteritis. Although such criteria may identify typical patients with a distinct form of vasculitis, they are not intended to establish a diagnosis in an individual patient; rather, they should aid comparability of different patient groups in various research endeavors.