This article has emphasized the extreme polymorphism of cutaneous manifestations in the course of systemic vasculitis. Skin involvement, which may represent the onset of the clinical picture in many cases, does not permit an immediate diagnosis but may orient the physician to further investigations. In our experience most patients who are referred to the dermatologist suffer from cutaneous features in apparent absence of visceral involvement. This group of patients forms a distinct subset of vasculitis characterized by the same polymorphic pattern of skin lesions observed in the systemic forms. The rare involvement of multiorgan systems suggests the existence of a continuum between cutaneous forms and systemic vasculitic syndromes as classified by the ARA. The causes of this protean clinical expression should be further investigated: different and, until now, unrecognized factors may act synergistically with common pathogenetic mechanisms. These factors could be represented by the existence of particular lymphocyte subsets with selective skin homing or by an anatomical background. The similarity of the therapeutic approach provides additional evidence for this unifying hypothesis.