Vasculitis can be very serious. In an extreme situation, when a segment of a blood vessel becomes weakened, it may then stretch and bulge (called an aneurysm). The wall of the blood vessel can become so weak that it ruptures and bleeds, possibly causing death. Fortunately, this is a very rare event.
If a blood vessel becomes inflamed and narrowed, the blood supply to the area of the body it serves may be partially or completely blocked. If alternate blood vessels (called collateral blood vessels) are not available in sufficient quantity to carry the blood to such sites, the tissue supplied by the affected vessels will die. Because vasculitis can occur in any part of the body, any tissue or organ can be affected.