Pityriasis Alba

Description

• Characterized by one or more poorly marginated, pale pink, or tan/white patches and plaques that commonly appear on the cheeks, neck, and lateral arms of children and young adults
• Variants: classic (CPA: most common; endemic and atopic subtypes), extensive (EPA: teenagers, females > males, larger lesions >2 cm, trunk, shoulders, neck); pigmenting (PPA: only seen on dark skin, bluish lesions, 1.5-cm lesions, female > male, forehead, cheeks more common locations)
• System(s) affected: skin/exocrine
• Synonym(s): pityriasis streptogenes; pityriasis simplex faciei; impetigo sicca; pityriasis maculata; pseudoleucoderma atopicum

Epidemiology

Prevalence

• Ranges from 1.9% to 5.2%, more common in dark skin phototypes, male = female (some variants more common in females)
• Predominant age: 90% of affected patients are aged 6 to 12 years; rare >25 years

Etiology and Pathophysiology

• Possibly tyrosinase inhibition by Malassezia furfur, postinfectious inflammation leading to hypopigmentation, low levels of serum copper (important in melanin production) (1)
• Atopic-dermatitis-related type likely due to eczema exacerbation and postinflammatory hypopigmentation (2)
• Other implicated causes: xerosis, excessive sun exposure, inappropriate skin care, excessive washing which reduces skin defenses and protecting factors

Genetics

• Associated with carriers of a loss-of-function mutation in the gene for filaggrin, important for structural integrity and hydration of the epidermis
• Mutations in this gene are also associated with atopic dermatitis.

Risk Factors

Young age, dark skin, atopic dermatitis, low socioeconomic status, overexposure to light, frequent bathing, exfoliation

General Prevention

No known preventive measures (Sun protection may minimize visibility of lesions.)

Commonly Associated Conditions

Atopic dermatitis