Pityriasis rosea in Lagos.

A recent 5-year period study of the incidence of pityriasis rosea among dermatologic outpatients was conducted at the Lagos University Teaching Hospital. Three hundred fifty-two patients with pityriasis rosea were seen. The average annual incidence was 4.8 per 100 dermatologic patients. Women predominated by a margin of 1.2:1.0. More than 91% of the patients were between the ages of 5 and 35 years, with a peak at ages 10-14. The incidence of the disease was significantly higher in the early part of the rainy season. No declining incidence was observed over the years. A blood picture of a leukopenia with relative lymphocytosis was observed early in the disease. Ampicillin, when consumed after the onset of the eruption, made the patient with pityriasis rosea clinically worse.