Pityriasis alba is a relatively common condition, which tends to occur in children and adolescents. The condition is classified as a subtype of eczema. The cause of this condition is unknown, however several triggering factors exist. These include excessive dryness of the skin and exposure to sunlight.
Pityriasis alba is characterised by solitary or multiple, round to oval patches with a fine branny scale. These patches occur commonly on the face, upper arms, neck or shoulders. With time, these scale fall off leaving sharply demarcated red patches. These patches become white or hypopigmented with time. These patches may extend and coalesce to form bigger patches. Sometimes the centre may become hyperpigmented. As a rule, pityriasis alba is asymptomatic, however there may be mild pruritus.
The prognosis for this condition is excellent, with most of the lesions tending to disappear with time. It may take several months to a few years for spontaneous repigmentation to occur. However, the repigmentation can be accelerated with treatment.
This condition responds to treatment with bland emollients and moisturisers on the affected areas. Excessive exposure to sunlight should be avoided and photoprotection in the form of sunscreens must be used. Oral PUVA therapy has been documented to be effective in a few resistant cases.