Erythema Multiforme on the Knees

Erythema multiforme on the knees. Erythema multiforme is just as varied in appearance as its name suggests. Often if occurs on the extensor surfaces of the extermities, as in this picture. The causes of EM are also varied. One of the most common ones is recurring HSV infection; however, the cause frequently remains unidentified.

Picture and text: Raimo Suhonen