Updated: 10/5/2017

Onychomycosis

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Snapshot
  • A 7-year-old boy presents to his pediatrician’s office for a white rash on his nails. His mom reports that he has a history of tinea pedis and tinea manuum and thought that this might be related. On physical exam, his left fourth and fifth finger have a thin, white, and powder-like discoloration of the nail plate. He is given topical therapy for this rash.
Introduction
  • Clinical definition
    • a dermatophytosis
      • superficial fungal infection of the nail
        • involving nail bed and underside of nail plate
        • also called tinea unguium
      • types of onychomycosis
        • distal and lateral subungual onychomycosis
          • most common
          • affects nail bed and underside of nail plate
          • due to Trichophyton rubrum
        • superficial white onychomycosis
          • common in children
          • affects surface of nail plate
          • due to Trichophyton mentagrophytes
        • proximal subungual onychomycosis
          • uncommon
          • usually in immunocompromised patients
          • affects proximal nail plate
          • due to Trichophyton rubrum
  • Epidemiology
    • prevalence
      • 3% prevalence in adults
      • 20% prevalence in adults > 60 years old
    • demographics
      • male > female
      • adults > 60 years old
    • location
      • toenails > fingernails
    • risk factors
      • moist and warm environment
      • increasing age
      • immunosuppression
      • occlusive shoes
      • communal baths
  • Etiology
    • dermatophytes
      • Trichophyton
        • most commonly Trichophyton rubrum
      • Microsporum
      • Epidermophyton
    • Candida spp.
      • less common cause of onychomycosis
  • Pathogenesis
    • fungal infection of keratinized tissue of nail plate
  • Associated conditions
    • tinea pedis
    • tinea cruris
  • Prognosis
    • high rates of recurrence
Presentation
  • Symptoms
    • asymptomatic
  • Physical exam
    • distal and lateral or proximal subungual onychomycosis
      • thickened with white, yellow, or brown discoloration
      • thickened nail may separate from nail bed (onycholysis)
      • most commonly affects first or fifth nail
    • superficial white onychomycosis
      • white discoloration of nail plate
      • powder-like
Studies
  • KOH preparation
    • skin scrapings at active edge of lesion mixed with KOH
    • presence of septated hyphae and spores indicates fungal infection
  • Calcofluor white staining
    • presence of branching hyphae
  • Fungal culture
    • performed if confirmation is needed or if KOH or calcofluor testing is negative
  • Making the diagnosis
    • usually based on clinical history and physical exam but confirmation with the aforementioned tests are recommended
Differential
  • Bacterial infection
    • green or black discoloration may indicate Pseudomonas aeruginosa infection
  • Psoriasis
  • Trauma
Treatment
  • Medical
    • topical therapy
      • indications
        • when there is < 80% nail involvement and no involvement of the lunula
      • drugs
        • efinaconazole 10%
        • tavaborole 5%
    • oral therapy
      • indications
        • involvement of lunula
        • proximal subungual onychomycosis
        • lack of response to topical therapy
        • Candida onychomycosis
      • drugs
        • terbinafine
          • for dermatophytes
        • itraconazole
          • for dermatophytes and Candida spp.
  • Operative
    • nail avulsion
      • indication
        • severe onycholysis, thickening, or dermatophytomas
Complications
  • Secondary bacterial infection

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