What is Pityriasis Alba?

 

Pityriasis alba is a type of eczema that occurs commonly on the faces of children.  It presents with symmetrical lightening of the skin of the cheeks.  When the condition starts, there may some redness of the patches.  Fine scaling on the surface of the patches is common.  Often the redness is not noticed and the first manifestation of the condition is a loss of colour.  It is much more noticeable on pigmented skin than on light skins.  This is purely because of the greater contrast in colour between the light patches and the normal pigmented skin.

 

Cause:

 

The cause of Pityriasis alba is not known.  However, sunlight seems to be the most important contributory factor.  Prolonged sun-exposure is not required to produce Pityriasis Alba.  Short periods on intense sun-exposure often is adequate to trigger off the condition eg swimming, tennis, sitting in motor cars during sunlight hours etc.

 

Natural history:

 

Pityriasis is a self-limiting condition which often disappears spontaneously in about 6 months.  Limitation of sun-exposure helps to allow the skin to recover faster.

 

What other conditions can look like Pityriasis Alba?

 

Vitiligo - the skin is totally devoid of pigment and is white in colour.  In Pityriasis alba, the skin is lighter than the surrounding normal skin but is not ice white in colour.  In vitiligo, the skin colour cells (melanocytes) are damaged whereas in P alba, the surface of the skin (stratum Corneum) thickens in response to sunexposure but the number of melanocytes are not affected.

 

Pityriasis versicolor - a fungal infection caused by Pityrosporum ovale.  Much more common on the upper back and chest than on the face, it is made up of small (2-5mm) circles of flat, scaly patches which may coalesce to form large sheets.  This condition is curable with appropriate anti-fungals.

 

Treatment:

 

• Sunscreens, for obvious reasons form the mainstay of treatment

• Moisturisers are used to make the scaling less obvious.

• A mild steroid cream is used to suppress any inflammation which may be present.

• A broad brimmed hat and avoidance of midday sun exposure help to resolve the problem faster.