Pityriasis alba is a common skin disorder similar to very mild eczema, causing round or oval, colorless, finely scaled patches of skin. These patches usually occur on the cheeks. The disorder is most common in children and adolescents. The cause is unknown. The disorder is treated symptomatically with special creams -- patches usually clear, but may return. Pityriasis alba patches are more apparent in summer, especially in dark-skinned children, because they don't tan as well as
the surrounding skin.
Pityriasis alba is a mild form of dermatitis of unknown cause. It will clear up after a few months, or in some cases persist two or three years. The colour gradually returns completely to normal. No treatment is necessary, but a moisturizing cream may improve the dry appearance. If the patches are red or itchy, a mild topical steroid cream can be applied for a few days.
Pityriasis alba appears as superficial, pale pink to light brown macules with irregular, poorly circumscribed margins. It is round-to-oval in shape and can have slightly elevated borders. Initially the lesion starts as a subtle erythema, which progresses over weeks to produce the characteristic off-white macule with powdery scale. Two to three macules are usually present, with a diameter of 5 to 30 mm. They tend to be located in the midforehead, malar ridge, perioral, and periorbital areas. Involvement of the neck, trunk, back, limbs, and scrotum occurs less commonly. Patients are usually asymptomatic but can experience mild pruritus or burning.
Pityriasis alba is an eczematous dermatosis with hypomelanosis secondary to postinflammatory changes and the UV screening properties of the hyperkeratotic and parakeratotic epidermis. Drying agents such as sunlight, wind, or soap trigger the disorder on the predisposed fragile skin of children, similar to the effect of these agents in children with atopic dermatitis. Wells et al in 1960 concurred that the cause of pityriasis alba was a localized inflammatory reaction.
Although no treatment is necessary for the full skin color to return, lotions and moisturizers may help the skin return to normal faster. One percent hydrocortisone cream may also help to make the patches go away a little more quickly. One percent hydrocortisone cream available over the counter should be applied once to twice a day to the affected areas. The condition often goes away by itself after a few months to years.