Question
Taenia capitis
Answer
Tinea capitis is a dermatophyte infection of the scalp and hair, caused predominantly by Trichophyton and Microsporum species, occurring mainly in pre-pubertal children.
Clinical patterns: grey patch (scaly patches with hairs broken close to the scalp, Microsporum); black dot (hairs broken at the scalp surface, endothrix, Trichophyton tonsurans); kerion (a severe, painful, boggy inflamed lesion, risking scarring alopecia); favus (chronic, yellowish cup-shaped crusts, T. schoenleinii, now rare).
Hair invasion patterns: ectothrix (spores around the hair shaft, Microsporum, fluoresces green under Wood’s lamp); endothrix (fungal elements within the hair shaft, T. tonsurans, no fluorescence).
Laboratory diagnosis: Wood’s lamp examination; direct KOH microscopy of plucked hair; culture on Sabouraud dextrose agar.
Treatment: oral antifungal therapy (griseofulvin, terbinafine, or itraconazole) is required, since topical therapy alone cannot adequately penetrate the hair follicle.