Tinea capitis is a dermatophytosis Overview of Dermatophytoses Dermatophytoses are fungal infections of keratin in the skin and nails (nail infection is called tinea unguium or onychomycosis). Symptoms and signs vary by site of infection. Diagnosis is by... read more that mainly affects children, is contagious, and can be epidemic. Trichophyton tonsurans is the most common cause in the US, followed by Microsporum canis and M. audouinii; other Trichophyton species (eg, T. schoenleinii, T. violaceum) are common elsewhere.
Tinea capitis causes the gradual appearance of round patches of dry scale, alopecia, or both. T. tonsurans infection causes black dot ringworm, in which hair shafts break at the scalp surface; M. audouinii infection causes gray patch ringworm, in which hair shafts break above the surface, leaving short stubs. Tinea capitis less commonly manifests as diffuse scaling, like dandruff, or in a diffuse pustular pattern.
Dermatophyte infection occasionally leads to formation of a kerion, which is a large, boggy, inflammatory scalp mass caused by a severe inflammatory reaction to the dermatophyte. A kerion may have pustules and crusting and can be mistaken for an abscess. A kerion may result in scarring hair loss.
Diagnosis of Tinea Capitis
Potassium hydroxide wet mount
Sometimes a Wood light examination and sometimes culture
Tinea capitis is diagnosed by clinical appearance and by potassium hydroxide wet mount of plucked hairs or of hairs and scale obtained by scraping or brushing. Spore size and appearance inside (endothrix) or outside (ectothrix) the hair shaft distinguish organisms and can help guide treatment.
Blue-green fluorescence during a Wood light examination is diagnostic for infection with M. canis and M. audouinii and can distinguish tinea from erythrasma Erythrasma Erythrasma is an intertriginous infection with Corynebacterium minutissimum that is most common among patients with diabetes and among people living in warmer climates. Diagnosis is clinical... read more .
Fungal culture of plucked hairs can be done when necessary. A scalp lesion in a child that appears similar to an abscess may be a kerion; if necessary, cultures can help make the distinction.
Pearls & Pitfalls
Differential diagnosis of tinea capitis includes
Treatment of Tinea Capitis
Selenium sulfide shampoo
Terbinafine is becoming first-line treatment in children because of its shorter treatment duration. Children < 20 kg are given terbinafine 62.5 mg orally once a day, those 20 to 40 kg are given 125 mg once a day, and those > 40 kg are given 250 mg once a day typically for 2 to 4 weeks. Alternatively, children may be treated with oral griseofulvin, which is sometimes preferred by insurers because of its lower cost. Micronized griseofulvin suspension dosage is 10 to 20 mg/kg once a day (doses vary by several parameters, but maximum dose is usually 1 g/day) or, if > 2 years, ultramicronized griseofulvin 5 to 10 mg/kg (maximum 750 mg/day) once a day or in 2 divided doses with meals or milk for 6 to 8 weeks or until all signs of infection are gone.
An imidazole or ciclopirox cream can be applied to the scalp to prevent spread, especially to other children, until tinea capitis is cured; selenium sulfide 2.5% shampoo should also be used at least twice/week. Children may attend school during treatment.
Adults are treated with terbinafine 250 mg orally once a day for 2 to 4 weeks, which is more effective for endothrix infections, or itraconazole 200 mg orally once a day for 2 to 4 weeks or 200 mg 2 times a day for 1 week, followed by 3 weeks without the drug (pulsed) for 2 to 3 months. Treatment can also include selenium sulfide 2.5% shampoo.
For severely inflamed lesions and for kerion, a short course of prednisone should be added (to lessen symptoms and perhaps reduce the chance of scarring), starting with 40 mg orally once a day (1 mg/kg for children) and tapering the dose over 2 weeks.
Tinea capitis affects mostly children and can be contagious and epidemic.
Confirm tinea capitis by potassium hydroxide wet mount, fungal culture, or sometimes Wood light examination.
Treat with oral terbinafine or griseofulvin in addition to a topical antifungal.
Add a short course of oral prednisone for a kerion or severe inflammation.