Pityriasis alba is a common condition primarily affecting children, but not exclusively, and especially those with atopic diathesis (eg, asthma, allergic rhinitis and conjunctivitis, atopic dermatitis). It is characterized by hypopigmented macules or patches. Lesions may be asymptomatic or mildly pruritic and range in size from 0.5-5 cm. Classically, there is no preceding inflammatory stage, and, on examination, fine scale may be present. Often, the lesions are poorly demarcated; however, at times, the hypopigmentation may be well defined. The disorder is associated with dry skin (xerosis).
Pityriasis alba often has a chronic course, tends to relapse, and usually worsens in the summer with increased sun exposure. It predominately occurs in children between the ages of 3 and 16 years and is found equally in both sexes. In the majority of patients, spontaneous resolution typically occurs before adulthood. Lesions most commonly occur on the face and upper arms. This disorder is common in all ethnicities, although the hypopigmented lesions are more obvious in patients with darker skin phototypes.
The exact cause of the condition is unknown, although the characteristic hypopigmentation may be secondary to a preceding subclinical dermatitis. Environmental triggers such as heat, humidity, sunlight exposure, detergents / soaps, abrasive clothing, chemicals, and smoke, along with stress, may aggravate this disorder. Microorganisms such as Pityrosporum, Streptococcus, Aspergillus, and Staphylococcus may also be triggers. Evidence also suggests that pityriasis alba is a mild eczematous dermatitis.
Codes
ICD10CM: L30.5 – Pityriasis alba
SNOMEDCT: 402296004 – Pityriasis alba
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Differential Diagnosis & Pitfalls
Extensive cases may resemble the hypopigmented form of tinea versicolor, especially if hypopigmentation involves the face.
In vitiligo, the patches are completely depigmented and very well demarcated.
Unlike pityriasis alba, tinea corporis usually has raised borders.
Topical medication such as retinoic acid, benzoyl peroxide, and potent topical steroids may present in a similar fashion.
Psoriasis usually has a thicker scale and a more well-defined border than pityriasis alba.
Atopic dermatitis – Pityriasis alba may be a manifestation of postinflammatory hypopigmentation, seen in individuals with atopic dermatitis.
Although similar, seborrheic dermatitis is less commonly seen in preschoolers and school-aged children.
Nummular dermatitis is usually more well defined, the lesions are raised with more prominent scale, and there is intense pruritus.
Tuberous sclerosis usually includes hypopigmented patches on the trunk and presents at birth with associated seizure, intellectual disability, and other skin lesions; shagreen patches and angiofibromas.
Pityriasis alba is a common noncancerous (benign) skin condition affecting children. It appears as light-colored patches, especially on the cheeks.
Although the condition typically lasts 1 year or more without treatment, pityriasis alba usually resolves after puberty or by the time the child reaches adulthood.
The exact cause of pityriasis alba is unknown, though triggers may include:
Heat
Humidity
Heavily scented detergents or soaps
Abrasive clothing
Smoke
Stress
Who’s At Risk
Pityriasis alba occurs in children of all races and of both sexes. It is most common in children aged 3-16 years.
Children at higher risk for pityriasis alba include those with:
Asthma
Hayfever (allergic rhinitis)
Eczema (atopic dermatitis)
Dry skin (xerosis)
Signs & Symptoms
The most common locations for pityriasis alba include:
Cheeks, around the mouth, chin
Forehead
Neck
Shoulders, upper chest, and upper arms
Pityriasis alba appears as several (2-20) light-colored (hypopigmented) patches ranging in size from 1-4 cm. The patches may have slight and subtle surface patches (scale). Occasionally, the condition begins as mildly itchy, pink patches that develop into lightened patches of skin.
People often think that pityriasis alba gets worse in the summer, but it just becomes more obvious as the normal, surrounding skin becomes darker with sun exposure.
Self-Care Guidelines
If you suspect that your child has pityriasis alba, the most important self-care measure is to keep the skin well moisturized. Try the following:
Use non-soap cleansers or moisturizing soaps.
Apply moisturizers such as petroleum jelly (Vaseline) or fragrance-free ointments and creams.
Avoid sun exposure and wear sunscreen.
Apply over-the-counter hydrocortisone cream sparingly for 3-7 days.
When to Seek Medical Care
Call your child's doctor for evaluation if the condition does not improve with self-care measures, if it seems to be getting worse, or if it spreads to other areas.
Treatments
To make sure that there is no yeast or fungus present, your physician may wish to scrape some of the scales onto a slide and examine them under a microscope. This procedure, called a KOH (potassium hydroxide) preparation, allows the doctor to look for tell-tale signs of yeast infection. Pityriasis alba is not caused by an infection with yeast or fungus. Therefore, the KOH preparation should be negative.
Since pityriasis alba is benign and does not usually spread or last long, no treatment may be necessary. The physician will recommend many of the self-care measures listed above. In very severe widespread infections with pityriasis alba, the doctor may recommend:
Patient Information for Pityriasis alba in Child