Polymyalgia rheumatica/giant cell arteritis and other vasculitides.

The epidemiology of vasculitic syndromes encompasses a broad spectrum of diverse clinical syndromes. Almost all lack identified etiologic agents, and their clinical characteristics are determined predominantly by the size of the involved vessel and the end organs damaged. With the exception of giant cell arteritis/polymyalgia rheumatica in the elderly, and Henoch-Schönlein purpura and Kawasaki disease in the pediatric population, the vasculitic syndromes are infrequently observed diseases.