Pityriasis Rosea

Pityriasis rosea is a self-limiting skin rash that typically begins with a single red, slightly scaly patch called a herald patch, usually two to ten centimeters across, followed days or weeks later by a wider eruption of many smaller scaly spots. In people with light skin these secondary spots are pinkish with a red edge, while in darker skin they appear greyish, and they characteristically follow the natural lines of skin cleavage, producing a pattern often described as resembling the branches of a Christmas tree across the back and chest. About a quarter of those affected experience itching, which tends to ease as the rash develops, and some people have flu-like symptoms such as headache, joint pain, mild fever, and fatigue in the days before the rash appears. Its exact cause is unclear, though researchers suspect a link to human herpesvirus 6 or 7, and despite this it does not appear to be contagious. It affects about 1.3 percent of people at some point, most often between the ages of ten and thirty-five and more often in spring, and it typically clears on its own within about three months without leaving scarring.