Pityriasis alba

health Jan 26, 2022

Pityriasis alba is a common worldwide skin disorder that mostly affects children and young adults. It affects both the sexes equally and it particularly affects people with dark skin.
Pityriasis alba is not caused by a fungus and is not contagious.
The condition is so named for its initial scaly appearance (pityriasis), and pale color of the patches that develop (alba) later which are not totally depigmented.
Pityriasis alba looks like multiple, discrete, poorly outlined hypo pigmented (whitish) or pinkish spots and patches which are usually dry, with or without the scaly appearance.
The patches are usually round, oval, or have a wavy-shaped border. Some are smaller than a coffee bean or larger than a golf ball.
Generally, a patch of pityriasis alba evolves through several stages.

Raised and pale: Slightly scaly pink patch or plaque with a just palpable popular surface.
Smooth flat pale patches: Hypo pigmented patch or plaque with fine surface scale.
The post-inflammatory hypo pigmented macule without scale.
The patches dry with very fine scales.
Resolution: usually resolves spontaneously, and the skin colour gradually returns back to normal with no scarring.

These patches are seen most commonly on the cheeks, around the mouth, chin, upper arms, neck, or shoulders, chest, and back.
The affected area can be mildly itchy but usually causes no problems. Sometimes it can appear and feel dry.
The patches usually disappear with moisturizing creams or go away on their own. Often they leave pale marks on the skin after the redness has faded.
The affected area can be mildly itchy but usually causes no problems.
Patches may persist for a few years, and may come and go periodically.
In summer, the patches become more prominent due to the tanning of non-affected skin.
During the winter, dry scaling appears due to the dry air inside homes.

Causes

The exact cause is unknown. However, it is commonly considered a mild form of atopic dermatitis, a type of eczema, which is a common skin disorder that causes scaly, itchy rashes.

People with very sensitive skin or who get a lot of sun may be more likely to get the condition and the triggers may include:

Heat
Humidity
Heavily scented detergents or soaps
Abrasive clothing
Smoke
Stress

Risk factors

People at higher risk for pityriasis alba are those with:

Asthma
Hay Fever (allergic rhinitis)
Eczema (atopic dermatitis)
Dry skin (xerosis)

Diagnosis

Pityriasis Alba can be diagnosed by its appearance and generally, tests are not needed.
But it can be confused with several other disorders that cause hypopigmentation and to exclude these, clinical examination should be done.
It includes,
Wood lamp examination: Shining a Wood's light over the skin may reveal lesions which are not clearly visible.
Scrapings for mycology: In the case of pityriasis alba microscopy and fungal culture results will be negative.
Skin biopsy: rarely required, helps reveal mildly spongiotic dermatitis and reduction in melanin.

Treatment

Pityriasis alba is benign and does not usually spread or last long. So, the treatment may not be necessary. The patches usually go away with time.
Medical treatment is not needed unless the skin is uncomfortable from itching.
To manage the redness, scales and itch if present emollients and a moisturizing cream or a weak topical steroid cream such as hydrocortisone, (0.5-1%) can be used.
In some cases, doctors may prescribe a nonsteroidal cream, such as pimecrolimus. Both types of creams can help reduce skin discoloration and relieve any dryness, scaling, or itchiness.
As the patches of pityriasis alba do not darken normally in sunlight, effective protection from sun and cosmetic camouflage help minimize the discrepancy in colouration against the surrounding normal skin.
Sunscreens may prevent the patches from becoming more noticeable in summer, by reducing the tanning of the non-affected skin.
Calcineurin inhibitors, non-steroid creams such as pimecrolimus cream and tacrolimus ointment, may be as effective as hydrocortisone and have been used to speed recovery of skin colour.
Both non steroid creams and steroid creams can help reduce skin discoloration and relieve any dryness, scaling, or itchiness.
In exceptionally severe cases, such as, very severe widespread infections with pityriasis alba, the doctor may recommend,
Prescription-strength corticosteroid (cortisone) cream
Ultraviolet light therapy