OverviewThis is a picture of microscopic polyarteritis on the shin. The term polyarteritis means that many blood vessels are inflamed. These nodules are located just below the skin's surface (subcutaneous), are barely felt when pressing on the skin (palpable), and are tender. The skin is typically red (erythematous).
Update Date 1/20/2015
Updated by: Gordon A. Starkebaum, MD, professor of medicine, division of rheumatology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.