Vasculitis simulators and vasculitis look-alikes.

A variety of common and uncommon nonvasculitic disorders may mimic vasculitis clinically, angiographically, or even histologically. These are the vasculitis simulators and vasculitis look-alikes. It is important to distinguish these vasculitis simulators from true vasculitis in order to avoid the unnecessary and harmful side effects of corticosteroids and cytotoxic agents, the mainstay of drug therapy for vasculitis.