OverviewThese red (erythematous), hive-like (urticarial) spots (plaques) are caused by inflammation of the blood vessels (urticarial vasculitis) and do not change over a 24-hour period. They may or my not turn white (blanch) with pressure.
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.