Pityriasis (Gk pityron, bran) alba (L albus, white) is a pattern of dermatitis in which hypopigmentation (with branny scaling) is the most conspicuous feature. Erythema (with branny scaling) usually precedes the development of hypopigmentation but this is often relatively mild. At times, there may be initial minimal serous crusting. The hypopigmentation is more noticeable in pigmented skin, summer and after sun tanning. The scaling is more noticeable in winter.
The individual lesion is a rounded, oval or irregular hypopigmented patch that is usually not well marginated. The course is extremely variable. Post inflammatory hypopigmentation (without scaling) ensues before resolution occurs. Recurrent crops of new lesions may develop at intervals. Pityriasis alba is sometimes a manifestation of atopic dermatitis but it is certainly not conﬁned to atopic individuals.
Although pigment is reduced, melanocyte numbers are not (the activity is decreased) and may even be increased relative to healthy skin.
Pityriasis alba occurs predominantly in children between the ages of 3 and 16 years. Both sexes are equally susceptible. The lesions are often conﬁned to the face, and are most common around the mouth, chin and cheeks. In 20% of affected children the neck, arms and shoulders are involved as well as the face. Less commonly, the face is spared and there are scattered lesions on the trunk and limbs as shown on this patient’s skin.
The age incidence, the ﬁne scaling and the distribution of the lesions usually suggest the diagnosis. Mycosis fungoides may present with lesions clinically resembling pityriasis alba. This condition may also be difficult to distinguish histopathologically, so follow-up and repeat biopsies are sometimes required.
Topical calcineurin inhibitors, pimecrolimus and tacrolimus, have been reported to speed recovery of skin colour.
|Topical pimecrolimus has been reported to speed recovery of skin colour as shown here.|
This page was last updated in October 2016.