Pityriasis Rosea

I. INCIDENCE Nékám1observed pityriasis rosea in 4 per cent of 100,000 cases of cutaneous disease, while Stelwagon,2in 123,746 cases collected by the American Dermatological Association from 1878 to 1887, found the disease in only 0.057 per cent. MacLeod3found 3 cases of pityriasis rosea per thousand cases of cutaneous diseases in children under 14 years of age observed at the Victoria Hospital. Graham Little4saw 6.7 cases per thousand in a dermatologic clinic for adults and children and 4.7 per thousand in a children's clinic. Benedek5quoted statistics from thirteen authors. The frequency of pityriasis rosea in Leipzig was 0.52 per hundred and in Vienna, 1.67 per hundred cases of cutaneous diseases. The frequency index (cases per month) was 0.54 for New York city and 9.7 for Berlin. Bolam3found that pityriasis rosea comprised 0.3 per cent of all dermatoses; Crocker,6