Inflammation of the blood vessels (vasculitis) may be caused when antibodies that have attached to antigens in the blood (immune complexes), attach to the blood vessel walls. 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: 4/20/2013 Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.