Dermatologic Manifestations of Pityriasis Alba Clinical Presentation

Lesions in pityriasis alba are commonly asymptomatic, although some patients report mild pruritus or a burning sensation.

Lesions tend to worsen in the summer with increased sun exposure.

Erythema is usually mild and may initially be conspicuous. Minimal serous crusting may even occur at a few points on the surface of some of the pityriasis alba plaques. Erythema later subsides completely to leave areas of hypopigmentation with or without fine scaling.

At the stage when a physician commonly observes pityriasis alba lesions, they show only persistent fine scaling and depigmentation. This commonly induces the patient to seek advice.

Pityriasis alba may be conspicuous in heavily pigmented skin. In lighter skins, pityriasis alba may become conspicuous after sun tanning. Pityriasis alba is considered a skin disorder of late summer because reports describe that excessive and unprotected sun exposure are strongly related in the development of pityriasis alba.^[6]

Pityriasis alba is associated with atopic diathesis. Inquire about a patient and family history of eczema, asthma, and/or hayfever.^[7]

The course of pityriasis alba is extremely variable. Most cases persist for several months, and some still show hypopigmentation for a year or more after all scaling subsides. Hypopigmentation may persist for years but eventually resolves spontaneously.

Recurrent crops of new lesions may develop at intervals.

The average duration of the common facial form in childhood is a year or more.

Widespread cases overlap with a condition termed progressive and extensive hypomelanosis.^[8] Progressive and extensive hypomelanosis occurs mainly in women from 18-25 years, with progressive development of round, pale coalescent macules mainly on the back that are unresponsive to therapy but spontaneously regress within 3-4 years.^[9]

The individual pityriasis alba lesion is a rounded, oval, or irregular plaque that is red, pink, or skin colored and has fine lamellar or branny scaling with indistinct margins. Several patches are usually observed.

In children, pityriasis alba lesions are often confined to the face and are most common around the mouth, chin, and cheeks (see the image below). Legs and trunk are less commonly involved.

In 20% of affected children, the neck, arms, and face are involved. Less commonly, the face is spared and scattered pityriasis alba lesions are observed on the trunk and limbs.

Pityriasis alba lesions usually range from 0.5-2 cm in diameter but may be larger, especially on the trunk.

Two uncommon variants exist, a pigmenting variety and an extensive type. In pigmenting pityriasis alba, the typical lesion is a central zone of bluish hyperpigmentation surrounded by a hypopigmented, slightly scaly halo of variable width, usually confined to the face and often associated with dermatophyte infection.^[10] Extensive pityriasis alba is differentiated from the classic form by the widespread and symmetrical involvement of the skin, no preceding inflammatory phase, a higher female-to-male ratio, and, histologically, the absence of spongiosis.^[11] In the extensive variant, lesions are less erythematous and less scaly, more persistent, asymptomatic, and more frequently seen on the trunk and less on the face.^[1]

The cause is unknown. The condition has been regarded as a manifestation of atopic dermatitis or other mild forms of eczema.

Reported contributory factors related to the development of pityriasis alba are excessive and unprotected sun exposure, poor hygienic habits, and environmental influences such as temperature, humidity, and altitude.^[6]