Inflammation of the blood vessels (vasculitis) may be caused when antibodies that have attached to antigens in the blood (immune complexes), are deposited on the blood vessel walls in the skin and many other organs. These purplish spots can be felt in the skin. They do not turn white (blanch) when pressed. As the condition progresses, they may become larger and more bruise-like (ecchymotic), and some may develop central ulceration or necrosis (tissue death).
Review Date: 1/25/2013
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.