Pityriasis alba
Pityriasis alba is a common, benign, self-limited dermatosis of children and adolescents that presents as round or oval hypopigmented macules and patches on the face, upper trunk, and upper limbs, often preceded by mild erythema and fine scale, and is more noticeable in darkly pigmented skin. Diagnosis is clinical, and treatment consists of emollients plus a low-potency topical corticosteroid such as hydrocortisone 1% ointment applied twice daily for 7 to 14 days for active, itchy, or scaly lesions.
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What this article covers
- Overview
Definition: pityriasis alba is a common, benign dermatosis presenting with hypopigmented macules and patches, occurring predominantly in children and adolescents.
- Epidemiology
Predominantly a disease of children and adolescents.
- Risk factors
Atopic dermatitis or atopic diathesis: the strongest recognized association; pityriasis alba is regarded in many patients as a minor cutaneous manifestation of atopic dermatitis.
- Pathophysiology
Reduced epidermal pigment without loss of melanocytes: histopathology shows markedly reduced pigment in the epidermis without a significant reduction in melanocyte count, distinguishing the mechanism from disorders that destroy melanocytes.
- Clinical features
Hallmark lesion: multiple asymptomatic, round or oval, hypopigmented macules and patches, most often on the face, upper trunk, and upper limbs; this pattern of ill-defined hypopigmented macules in a…
- Differential diagnosis
Vitiligo: sharply demarcated, completely depigmented (not merely hypopigmented) macules that fluoresce bright white and sharply delineated under Wood's lamp, unlike the accentuated but…
- Diagnosis
The diagnosis is clinical, based on the characteristic appearance and distribution of asymptomatic, ill-defined, round or oval hypopigmented macules and patches in a child or adolescent; there are no…
- Management
First, counsel that pityriasis alba is benign and self-limited, since expectation-setting reduces unnecessary anxiety and treatment pressure, particularly for asymptomatic or minimally symptomatic lesions.
- Complications
Cosmetic disfigurement: the hypopigmented patches, particularly on the face, can be a source of visible cosmetic concern, more so in darker skin types.
- Prognosis
Self-limited disease: pityriasis alba resolves without intervention, though the time to resolution ranges from several months to a few years.
- Prevention
Daily broad-spectrum sunscreen, SPF at least 30, applied at 2 mg per square centimeter and reapplied every two hours during outdoor exposure, reduces the tanning-related contrast that makes lesions more visible.
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Related articles
- Atopic dermatitis
Atopic dermatitis is a chronic, pruritic, relapsing inflammatory skin disease of the face and flexural surfaces driven by a compromised skin barrier and an exaggerated immune response, often accompanying allergic rhinitis and asthma as part of the atopic triad. First-line treatment is fragrance-free emollients plus a topical glucocorticoid for active flares, escalating to topical calcineurin inhibitors, phototherapy, or systemic agents such as dupilumab for disease recalcitrant to topical therapy.
- Vitiligo
Vitiligo is a common acquired autoimmune condition in which destruction of melanocytes produces well-demarcated, completely depigmented macules and patches without scale, most often on the extensor surfaces, hands, face, and periorificial skin. Diagnosis is clinical, supported by Wood's lamp examination showing bright, sharply delineated fluorescence, and first-line treatment is a topical high-potency corticosteroid or a topical calcineurin inhibitor such as tacrolimus, with phototherapy for widespread disease.
- Tinea versicolor
Tinea versicolor (pityriasis versicolor) is a common superficial fungal infection caused by Malassezia yeast, producing hypopigmented, hyperpigmented, or erythematous scaly macules that coalesce into patches on the upper trunk and fail to tan with sun exposure. Diagnosis is confirmed by a potassium hydroxide preparation showing a spaghetti-and-meatballs pattern, and first-line treatment is topical ketoconazole 2% shampoo or selenium sulfide 2.5% lotion, with oral itraconazole reserved for extensive or recurrent disease.
- Seborrheic dermatitis
Seborrheic dermatitis is a common chronic inflammatory reaction to Malassezia yeast that produces ill-defined erythema with dry or greasy scale in sebum-rich sites such as the scalp, nasolabial folds, brows, and ears. Diagnosis is clinical based on distribution; first-line treatment is topical ketoconazole cream or shampoo with a short course of low-potency hydrocortisone for inflamed flares, and disseminated or severe disease should prompt screening for HIV or a neurologic disorder.