[Symptomatic or secondary allergic vasculitis. Pathogenesis of cutaneous vasculitis].

The histopathologic alterations of the allergic cutaneous vasculitis (fibrinoid necrosis of the walls of the small blood vessels with infiltration of neuthrophils in Karyorrexis) is seen in several entities. It is possible to divide such entities in two groups: a) Primitive allergic vasculitis in which the vascular lesion is dominant and. b) Secondary allergic vasculitis in which the vascular alterations, not constant, are integrants of variable histopathologic conditions. Many classifications have deen done on clinical and pathological bases. Such classifications are not satisfactory. A classification in base of physiopathologic and immunologic mechanisms could permit adequate therapeutic planning. In this paper we consider the secondary vasculitis only. The secondary angitis are seen in: 1) Difuse colagen diseases. 3) Conditions related to infections or inflamatory processes. 3) Angitis produced by drugs. 4) Conditions produced by insects or parasites bites. 5) Heterogeneous group that include diferent tipes of not necrotizing sistemic angitis in uhich, some times, trombosant and necrotizing processes are associated.