This violet-colored inflammation (erythema) over the knuckles is caused by Dermatomyositis. Other skin conditions produce more redness, while the color of this lesion is violet. There may also be inflammation in the muscle tissue.
Review Date: 1/22/2013 Reviewed By: Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.