OverviewThese spots of blood under the skin (purpura) are caused by vasculitis. They do not turn white with pressure (non-blanchable). In this particular case, the purpura are associated with an underlying disorder affecting the structure of the blood vessel walls (collagen-vascular disorder).
Update Date 4/28/2015
Updated by: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.