Pityriasis alba

Definition

Pityriasis alba is a common skin disorder of patches of light-colored (hypopigmented) areas.

Causes

The cause is unknown but may be linked to atopic dermatitis (eczema). The disorder is most common in children and teens. It is more noticeable in children with dark skin.

Symptoms

The problem areas on the skin (lesions) often start as slightly red and scaly patches that are round or oval. They usually appear on the face, upper arms, neck, and upper middle of the body. After these lesions go away, the patches turn light-colored (hypopigmented).

The patches do not tan easily. Because of this, they may get red quickly in the sun. As the skin surrounding the patches darkens normally, the patches may become more visible.

Exams and Tests

The health care provider can usually diagnose the condition by looking at the skin. Tests, such as potassium hydroxide (KOH), may be done to rule out other skin problems. In very rare cases, a skin biopsy is done.

Treatment

The provider may recommend the following treatments:

• Moisturizer
• Mild steroid creams
• Medicine, called immunomodulators, applied to the skin to reduce inflammation
• Treatment with ultraviolet light to control the inflammation
• Medicines by mouth or shots to control the dermatitis, if very severe
• Laser treatment

Outlook (Prognosis)

Pityriasis alba usually goes away on its own with patches returning to normal pigment over many months.

Possible Complications

Patches may get sunburned when exposed to sunlight. Applying sunscreen and using other sun protection can help prevent sunburn.

When to Contact a Medical Professional

Call your provider if your child has patches of hypopigmented skin.

References

Habif TP. Light-related diseases and disorders of pigmentation. In: Habif TP, ed. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 6th ed. Philadelphia, PA: Elsevier; 2016:chap 19.

Patterson JW. Disorders of pigmentation. In: Patterson JW, ed. Weedon's Skin Pathology. 4th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2016:chap 10.