Question
Dermatophytosis
Answer
Dermatophytosis refers to fungal infections of keratinized tissue (skin, hair, nails) caused by dermatophytes — genera Trichophyton, Microsporum, and Epidermophyton — collectively known as tinea/ringworm infections.
Classification by habitat: anthropophilic (human-adapted, e.g., T. rubrum); zoophilic (animal-adapted, e.g., M. canis); geophilic (soil-dwelling, e.g., M. gypseum).
Clinical patterns: tinea capitis (scalp), tinea corporis (body — annular lesion with central clearing and active advancing edge), tinea cruris (groin), tinea pedis (feet), tinea unguium/onychomycosis (nails).
Laboratory diagnosis: Wood’s lamp examination (some Microsporum species fluoresce green); direct KOH microscopy showing septate, branching hyphae; culture on Sabouraud dextrose agar for species identification.
Treatment: topical antifungals for limited disease; oral antifungals (terbinafine, itraconazole, griseofulvin) for extensive disease, tinea capitis, or onychomycosis.