Walsh & Hoyt: Hypersensitivity Vasculitis

The term hypersensitivity vasculitis is used to describe a group of conditions that are characterized by damage to small blood vessels of the skin and occasionally of other organs. These conditions are also called ""leukocytoclastic vasculitides,"" because the pathologic process is infiltration of the small blood vessels by PMNs, destruction of the vessel walls, and fragmentation of the leukocytes. The pathogenesis of hypersensitivity vasculitis seems to be a reaction to one or more antigens, often drugs.