Vasculitis is an inflammation of the blood vessels.
Inflammation is a condition in which tissue is damaged by blood cells entering the tissues.
These are mostly white blood cells which circulate and serve as our major defense against infection. Ordinarily, white blood cells destroy bacteria and viruses. However, they can also damage normal tissue if they invade it. Several things can happen to an inflamed blood vessel. If it is a small vessel, it may bread and produce tiny areas of bleeding in the tissue.