DermatologyPending review

Fungal skin infections

Dermatophyte fungi digest keratin in the stratum corneum and spread outward as they consume it, producing a scaly lesion with an actively advancing, inflamed edge and a clearing centre, the ring that gives ringworm its name.

In a nutshell

Dermatophytes digest keratin and spread outward from the point of inoculation, so the advancing edge shows the most fungus and inflammation while the centre, already consumed, heals and clears, producing the classic ring. Site determines the clinical name and appearance.

Classic presentation

An itchy, scaly annular lesion with a well-defined active edge and central clearing, or fungal changes at the feet, groin, scalp or nails depending on site.

Key points

Dermatophytes only infect dead keratin, which is why infection stays superficial in immunocompetent hosts.

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Educational content pending clinical review. Not medical advice.