Urticarial vasculitis and hypocomplementemic urticarial vasculitis syndrome.

Urticarial vasculitis is a clinicopathologic entity in which episodes of urticaria are accompanied by histopathologic features of cutaneous vasculitis. The histopathologic definition of vasculitis varies from report to report. In this article, vasculitis is defined as histopathologic features of blood vessel damage: There should be evidence of leukocytoclasis and vessel wall destruction, which may or may not be accompanied by fibrinoid deposits. Red blood cell extravasation and perivascular inflammatory cell infiltrate also may be present. The extent to which each of these elements must be present has been debated.