Causes and Treatment of Pityriasis Alba in Children

Pityriasis alba is a common, benign skin disorder that typically affects children between the ages of six to 12. This condition is characterized by patches of lighter skin mainly on the face, although the neck, upper chest, and arms are sometimes involved.

The condition is so named for its scaly appearance (derived from the Latin word "pityrus" meaning bran) and characteristic white patches ("alba" for white).

Pityriasis alba is thought to be caused when an acute case of dermatitis heals and leaves behind a lighter patch of skin. It may also result from the overuse of topical corticosteroids when treating eczema; doing so can cause areas of patchy rash to lighten as they heal.

Certain genetic disorders are also believed to cause cutaneous hypopigmentation (loss of skin color) due to the reduced activity of melanocytes, the cells that produce the pigment melanin.

It is estimated that five percent of children in the U.S. will get pityriasis alba at some point in their early school years, according to a 2015 study in the Journal of Clinical Medicine.

Pityriasis alba lesions are most often found on the cheeks and typically range from a quarter of an inch to an inch in size. The borders of the lesions are not clearly defined and gradually blend into the normally pigmented skin.

The lesions themselves are often raised and may be covered by very fine skin flakes. The scaly appearance is most noticeable during the winter months as a result of drier air. During the summer, tanning can make the lesions appear more prominently in contrast to the darkened skin tones.

Pityriasis alba is often confused with tinea versicolor in which the overgrowth of fungus on the skin causes white patchy lesions. There are several ways to distinguish between the two disorders:

• A Wood Light examination employed a handheld ultraviolet (UV) lamp to highlight differences in skin color. It is usually performed in a dermatologist's office in a darkened room.
• Potassium hydroxide (KOH) can be used to treat a light scraping of skin. When examined under a microscope, any evidence of fungus will be visibly highlighted, confirming tinea versicolor or other fungal conditions such as tinea corporis (ringworm).

Pityriasis alba can also be confused with vitiligo, a disease caused by the destruction of the melanocytes in the affected skin. Pityriasis alba can be distinguished from vitiligo by their borders.

Vitiligo has distinct borders and a starker contrast in dark and light tones. Vitiligo patches can also be larger and appear on sun-exposed parts of the body as well as the armpits, eyes, groin, genitals, naval, and rectal area.

Treatment of pityriasis alba is not considered necessary since it will resolve on its own. A moisturizer may help reduced the scaliness (especially on the face), while good skin hygiene will help speed recovery.

If there is itchiness, a 1% hydrocortisone cream can be used sparingly. Even with treatment, recovery can sometimes take several months. The avoidance of tanning, as well as the consistent use of sunscreen (minimum 30 SPF), can also help.