[Cutaneous necrotizing angiitis].
The term necrotizing angiitis signifies a histological lesion combining an inflammatory infiltration rich in pycnotic polynuclear cells to fibrinoid deposits of the vessels wall and/or of the near by collagen. This type of lesions may affect vessels of small caliber or vessels with a muscular wall (arterioles). In the skin, with the term necrotizing angiitis, is implied a lesion affecting the small vessels of the dermis, capillaries and mostly post-capillary venules. The most frequent, by far, clinical manifestation is a palpable purpura; more seldom, it may be lesions of urticaria, livedo or necrotic lesions. these cutaneous necrotizing angiitis may represent alone the entire symptomatology; they may be associated with varied deep localizations of the same type and finally combine with or precede diseases perfectly defined in other respects, especially collagen diseases. Thus, the term necrotizing angiitis refer to a multitude of entities, syndromes which it is only possible to regroup with many clinical, immuno-pathological, etiological and biological data, each of these data alone being an insufficient reference to characterize them.