Pseudovasculitis: mechanisms of vascular injury and clinical spectrum.

Pseudovasculitis, vasculitis-like syndromes, or mimics of vasculitis represent a heterogeneous collection of disorders that are capable of simulating a vasculitic disorder. Some conditions such as cardiac myxomas, cholesterol embolization, and fibromuscular dysplasia are more apt to cause confusion, but numerous other conditions can do so also. Inappropriate diagnosis leads to delay or absence of proper management and exposure to potentially deleterious treatment modalities such as corticosteroids and cytotoxic agents. The diagnosis of a pseudovasculitic disorder requires a high index of suspicion and should always be part of the differential diagnosis of vasculitis. The endothelium is thought to be pivotal in vascular injury; much has been learned using in vitro human umbilical vein endothelial cell cultures. Application of this knowledge to human disease and to vasculitic disorders and their imitators is still premature.