OverviewThis is Gottron's sign, seen in dermatomyositis (an inflammatory disease of the muscles and skin). Violet-colored inflammation over the knuckles is an important diagnostic finding in dermatomyositis, since other skin conditions produce more redness.
Review Date 2/8/2017
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, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.