Tinea unguium

• Meissner, 1853
• Virchow, 1854

Onychomycosis, nail mycosis, nail fungus.

• Fungal infection of the nails
• If the nail is infected with dermatophytes alone, it is called "tinea unguium". If yeasts or moulds infect the nail (or in the case of a mixed infection), it is an "onychomycosis"

Division

• Distal subungual onychomycosis (DSOM): most common type.
• Proximal subungual type (PSOM).
• White superficial onychomycosis (WOOM).
• Onychomycosis due to moulds.
• Onychomycosis due to Candida (Paronychia candidamycetica).
• Total dystrophic onychomycosis.
• Leukonychia trichophytica: whitish, superficial onychomycosis (usually caused by tryichophytes).
• Dystrophic onychomycosis: classic form seen in chronic mucocutaneous candidiasis.
• Onychia et Paronychia candidosa: usually caused by Candida albicans and is associated with chronic inflammation of the proximal and lateral nail wall. Discolouration and transverse grooves are seen

"Immune phenomena in dermatophytoses

• When the human organism is attacked by dermatophytes, antibodies are formed in the skin. This can be detected by means of intradermal testing.
• A type I or type IV reaction may occur after injection of (trichophytin)

• Incidence (Europe/USA): approx. 20%
• Incidence (Europe/USA) > 65 y.: up to 45%

• Exciter
  • Approximately 99% of all fungal nail infections are dermatophytes
  • Mostly:
    • Trichophyton rubrum (dermatophyte)
    • Trichophyton mentagrophytes (dermatophyte)
    • Candida albicans (yeast)
    • Candida tropicalis (yeast)
    • Scopulariopsis brevicaulis (mould)
    • Aspergillus niger (mould)
    • Hendersonula toruloidea (mould)

• In most cases, tinea pedis already exists. The pathogens enter the nail bed via the hyponychium
• In bakers, onychomycosis due to Candida may occur more frequently than in the normal population. The increased moisture work and nutrient supply provide a suitable environment for yeast fungi
• The toenails are affected significantly more often than the fingernails
• Predisposing factors
  • Trauma (CAVE too tight/short shoes)
  • Anatomical anomalies
  • ↓ Blood circulation (articular, venous)
  • Disorders of lymphatic drainage
  • Neuropathies
  • Diabetes mellitus
  • Immune suppression
  • Tinea pedum

• After the fungi have invaded the nail bed via the hyponychium, the subungunal hyperkeratosis causes the nail plate to detach (onycholysis semilunaris)
• A yellow discolouration is called "dyschromasia"
• The term "green nail syndrome" is used for secondary infestation with Pseudomonas aeruginosa
• ↑ subungual keratosis à crumb nails (onychodystrophy)

• Nail material removal:
• Disinfection with 70% alcohol
• As proximal as possible!
• Curettage technique
• Native and culture!
• Histological examination!

In case of pos. findings for moulds:

• Repeat 3 times (only if no dermatophytes can be detected 3 times is onychomycosis due to moulds to be assumed)

• Success rate: 50%
• Recurrence rates: 5%-20% or 40% (grisefulvin)

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