Vasculitis affecting the skin. A review.

Although cutaneous purpura and nodules are important clinical manifestations of vasculitis, many other cutaneous expressions of injury also can be caused by vasculitis. Once cutaneous vasculitis is recognized, patient evaluation should center on identifying causative agents, pathogenic mechanisms and extracutaneous organ system involvement, and diagnostic categorization of the disease. Once identified, some causative agents, such as an infectious pathogen, drug, or neoplasm, can be eliminated leading to resolution of the vasculitis. Recognition of the pathogenic category, such as immune complex-mediated vasculitis or ANCA-associated vasculitis, will narrow the differential diagnosis and suggest the likelihood and pattern of extracutaneous disease. Accurate diagnostic categorization, which will direct prognostication and treatment, usually requires integration of clinical, pathologic, and serologic data.