DESCRIPTION

Superficial fungal infections of the skin, hair, and nails are characterized by erythema, scaling, pruritus, and change in coloration.

EPIDEMIOLOGY

• Dermatophyte infections:
  • Tinea capitis:
    • Most common fungal infection in pediatric population
    • Occurs mainly in prepubescent children (between ages 3 and 7 years)
    • Asymptomatic carriers are common and contribute to spread.
  • Tinea corporis usually seen in younger children or in young adolescents with close physical contact to others (i.e., wrestlers)
  • Onychomycosis: Overall prevalence is 0–2.6% in children but increases with age and is uncommon in prepubertal children. It can often occur with concomitant tinea pedis or in 1st-degree relatives with infection.
• Candidiasis:
  • Majority of infants are colonized with Candida albicans, as such mild mucocutaneous infection can occur in healthy infants.
  • More invasive disease can occur in those with impaired immunity, such as extreme prematurity or neutropenia.
• Tinea versicolor: seen in adolescents and young adults

ETIOLOGY

• Varies by geographic region
• Dermatophyte infections:
  • Tinea capitis: >90% caused by Trichophyton tonsurans in North America—spread from human to human (anthropophilic); increasing incidence of Microsporum canis infection spread from animals such as cats and dogs to humans (zoophilic)
  • Tinea corporis: preadolescent children: M. canis, Microsporum audouinii, older children: Trichophyton rubrum, Trichophyton mentagrophytes, T. tonsurans
  • Onychomycosis: T. rubrum, T. mentagrophytes
• Candidiasis: Usually C. albicans (but there is a changing distribution of non-albicans species)
• Tinea versicolor: Malassezia furfur

GENERAL PREVENTION

• For dermatophyte infections, measures should be taken to avoid transmission between hosts, including no sharing of combs, brushes, hats, etc.
• Hair utensils and hats should be washed in hot, soapy water at onset of therapy.
• Pets should be watched and treated early for any suspicious lesions.
• In patients in whom appropriate therapy has not led to improvement in symptoms, siblings and close contacts should be examined and fungal cultures performed with antifungal susceptibility testing when indicated.
• Isolation of hospitalized patient is unnecessary.

PATHOPHYSIOLOGY

• Fungal elements (arthroconidia) adhere to stratum corneum or hair shaft. Proteases work to degrade keratin, which allows for invasion of dermatophytes.
• Predisposing factors may include moisture, macerated skin, and immunocompromise.
• Host immune response is usually able to contain infection.
• Inflammatory response is variable; highly inflammatory forms may lead to pustular lesions and kerion (large inflammatory mass) formation.