[Idiopathic vasculitides.]

Idiopathic vasculitides are systemic inflammatory diseases of vessels, chiefly arteries, of all sizes. The etiology of most vasculitides is unknown. Some are infectious, others involve the deposition of circulating immune complexes in vessel walls. Diagnosis is a composite of clinical symptoms and signs, serologies, histopathology, clinical course and response to therapy. Seven main groups of idiopathic vasculitides have been identified: Overlap syndromes are not uncommon, however, as classification is artificial inasmuch it is based more on consensus than on actual biological features. Giant cell (temporal) arteritis is a systemic inflammatory disease of the aorta and its major branches, especially extracranial arteries. Its etiology and pathogenesis are largely unknown. Elderly persons of Nordic descent, chiefly women, are primarily affected.