Pityriasis alba is a skin condition that primarily affects people between the ages of three and sixteen in children and young adults. It is common worldwide with a prevalence in children of around 5%. It affects males and girls female equally. Pityriasis alba hypopigmentation is more noticeable and possibly more prevalent in black skin types than in white skin types.

Etiology:

The etiology of pityriasis alba is idiopathic. It is usually associated with atopic dermatitis and dry skin. It frequently appears after sun exposure, maybe because the afflicted spots become more noticeable due to surrounding skin darkening. Ongoing research about the relationship between pityriasis alba and the following factors: UV radiation, insufficient or excessive bathing, low levels of copper, and Malassezia yeasts.

Clinical features:

The patients will usually present with 0.5 to 2 cm multiple hypopigmented patches or thin plaques on the cheek and chin. The patches could be oval, round, or irregular in shape with poorly defined edges. Usually, the patients will have absent or minimal itch. The dryness and scaling are more noticeable in the winter, while the hypopigmentation is more noticeable in summer.

Pityriasis alba patches undergo several stages:

The appearance of scaly pink with just a palpable surface.
The hypopigmentation stage with fine surface scale.
The post-inflammatory hypopigmented macule/ patch with no scale.
Resolution of the lesion.

Diagnosis:

The diagnosis is usually clinical, and the investigations are done to rule out other differential diagnosis:

Wood lamp: No enhancement in the cases of pityriasis alba.
Scrapings for mycology: negative in the cases of pityriasis alba.
Skin biopsy: Usually not indicated, would reveal spongiotic dermatitis and melanin reduction.

A dermoscopy of pityriasis alba will reveal, a poorly defined pale area, white structureless areas, superficial white scale, and normal hair color.

Management:

Asymptomatic pityriasis alba requires no treatment. A moisturizing cream to improve the dryness, and a mild topical steroids will reduce redness and itchiness if present. It has been observed that calcineurin inhibitors, such as tacrolimus ointment and pimecrolimus cream, speed up the return of skin color and maybe just as effective as hydrocortisone.

Psoralen + UVA photochemotherapy is used in severe situations, this treatment may aid in repigmentation; nevertheless, the likelihood of recurrence following treatment discontinuation is considerable. Laser therapy can be effectively treated with a twice-weekly, 308-nm excimer laser treatment for 12 weeks.

Prevention:

Sunscreen use could be utilized to reduce the development of pityriasis alba.

Outcome:

Pityriasis alba usually goes away in a year, although it might take anything from a few months to two or three years. The color gradually reverts to its original state.

Written by:

Mohammed Alahmadi, Medical Student.

Revised by:

Maee Barakeh, Medical Student.

References:

DermNet.

Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology.

Dermatology by Bolognia.