Although the initial lesions of pityriasis alba are mildly erythematous, the erythematous stage may go unnoticed. The most common presentation is asymptomatic (or mildly pruritic), hypopigmented lesions, often on the face. The patient or family history may include atopic dermatitis, allergic rhinitis, or asthma. The lesions may be an incidental finding on physical examination, although concern about the cosmetic appearance of the lesions on the part of the patient or the parent often leads to a consultation with a healthcare provider. The hypopigmentation often becomes more apparent with sun exposure (and darkening of the surrounding skin) during the spring and summer.

Physical examination reveals multiple round or oval-shaped hypopigmented macules or patches (or thin papules and plaques) with indistinct margins. There may be mild erythema and/or scaling. The lesions most commonly number from four to 20, measure 0.5 cm - 5 cm in size, and are distributed predominantly on the face, neck, upper arms, and upper trunk. Signs of atopic dermatitis may be present, including an eczematous rash in the popliteal or antecubital fossa, nipple eczema, cheilitis, and infra-auricular fissuring.[1][6]

It is important to carefully examine the patient because the scaly lesions may often represent psoriasis.

Based on the clinical appearance and distribution of the skin lesions in a child or adolescent, the diagnosis of pityriasis alba is, in most cases, straightforward.

The differential diagnosis of pityriasis alba includes postinflammatory hypopigmentation from any cause, fungal infections (tinea versicolor and tinea corporis), vitiligo, nevus depigmentosus (a stable congenital leukoderma), psoriasis, seborrhea, the ash-leaf macules of tuberous sclerosis, mycosis fungoides (cutaneous T-cell lymphoma), and hypopigmentation secondary to topical medications such as retinoic acid, benzoyl peroxide, and corticosteroids. In the proper geographic and clinical setting, the diagnosis of leprosy also should be considered.

If the diagnosis is uncertain, several diagnostic procedures may be useful. On examination with a Wood's lamp, the lesions of pityriasis alba may be accentuated but are nonfluorescent. This finding is in contrast to vitiligo, which will fluoresce more brightly and have edges with sharper demarcation. Potassium hydroxide (KOH) preparation of a skin scraping will be negative for fungal elements. This result is in contrast to tinea versicolor or tinea corporis, which will be positive for fungal elements. Skin biopsy is usually not necessary, but when performed, it can distinguish pityriasis alba from mycosis fungoides.[2][7]

Patients and their parents can be reassured regarding the benign and self-limited nature of pityriasis alba. However, they also should be made aware that its slow resolution may take several months to a few years, although most cases resolve within one year. The affected areas should be protected from sun exposure, as darkening of the surrounding skin may worsen the cosmetic appearance. Low-potency topical steroids, such as 1% hydrocortisone cream or ointment, may reduce erythema and pruritis and accelerate repigmentation. Mild emollients, such as petroleum jelly and creams, may reduce scaling. Sunscreen may help prevent the lesions from sunburning and decrease the darkening of the surrounding skin. Treatment with topical calcineurin inhibitors, such as 0.1% tacrolimus ointment and 1% pimecrolimus cream, have also been reported to be effective; however, because of their high cost, they are seldom indicated. Calcitriol, a topical vitamin D analog, showed comparable efficacy compared with tacrolimus. Other treatment options, usually reserved for extensive cases, include psoralen plus ultraviolet-A (PUVA) photochemotherapy and targeted phototherapy with a 308-nm excimer laser.[1]

• Atopic dermatitis

• Contact dermatitis

• Delusional tinea

• Discoid eczema 

• Leprosy

• Nevus anemicus

• Nummular eczema

• Pityriasis rosea

• Seborrhea

• Tinea corporis

Pityriasis alba is a self-limited infection and has a good prognosis. Complete repigmentation is the norm in most people. The key issue is the cosmetic deficit for which patients often seek medical help. Also, there is a risk of sunburn in areas of hypopigmentation. The skin disorder may last a few days or a few years. In some cases, the treatment may shorten the duration of the disorder.

Two uncommon variants of pityriasis alba have been described. The lesions of pigmenting pityriasis have a central zone of bluish hyperpigmentation surrounded by a hypopigmented halo. These are often associated with dermatophyte infection and are found primarily in darker skin types from South Africa and the Middle East. Extensive pityriasis alba is characterized by widespread, symmetrical, and more persistent involvement of the skin, lesions distributed predominantly on the trunk rather than on the face, a higher female-to-male ratio, and the histologic absence of spongiosis.[1][8][9]

Pityriasis is a common skin disorder which is best managed by an interprofessional team, because of the huge differential diagnosis.

Pityriasis alba is a common skin disorder managed by the primary care provider, nurse practitioner, dermatologist, and specially trained nurses.

The key is to educate the patient on the benign nature of the disorder. No treatment is required, and the condition spontaneously regresses in 12-24 months. For those who seek treatment for cosmesis, referral to a dermatologist is recommended. Many treatments are available, but there is no evidence to suggest that one is better than the other.  Moreover, some treatments are also more likely to cause more harm than good. [1] Some patients may benefit from a moisturizer. Dermatology nurses are often involved in patient education, arrange for follow up, and facilitate communication within the team. Pharmacists can assist in the selection of emollient creams and sunscreens, also participating in patient education.

Patients should be told to avoid the sun and wear a wide-brimmed hat and long-sleeved garments. Sometimes the UV light can worsen the scaling.

The outcomes in most patients are excellent, but the recovery may take months or years.