"I followed your advice and used the ringworm medicine for the spot on my hip. Now look at me," the sweet young thing said, displaying a torso covered with hundreds of oval scaling lesions. The "herald plaque" of pityriasis rosea (Fig 1) precedes the generalized eruption and resembles a superficial ringworm infection enough to result in frequent misdiagnosis. The patient then interprets the subsequent exanthem (Fig 2) as an unexpected result of the initial treatment.
Little is known about pityriasis rosea a century after Gilbert's description of the disease. Seasonal variations in incidence, with peaks in the spring and fall, account for periodic "epidemics." Cases do not cluster in families, houses, or dormitories, so contagion is apparently not a factor. The frequent occurrence during pregnancy is unexplained, unless there is merit in the unproved idea that new clothing acts as a precipitating factor. The disease develops most commonly in young
Kingery FAJ. A Distinctive Exanthem. JAMA. 1965;192(11):991. doi:10.1001/jama.1965.03080240061014