Tinea capitis is a dermatophyte infection of the scalp.
Tinea capitis is a dermatophytosis (see see Overview of Dermatophytoses) that mainly affects children, is contagious, and can be epidemic. T. tonsurans is the most common cause in the US, followed by Microsporum canis and M. audouinii; other Trichophyton sp (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.
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. 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.
Differential diagnosis of tinea capitis includes
Children are treated with micronized griseofulvin suspension 10 to 20 mg/kg po once/day (doses vary by several parameters, but maximum dose is generally 1 g/day) or, if > 2 yr, with ultramicronized griseofulvin 5 to 10 mg/kg (maximum 750 mg/day) po once/day or in 2 divided doses with meals or milk for 4 to 6 wk or until all signs of infection are gone. Terbinafine also may be used. Children < 20 kg are given terbinafine 62.5 mg po once/day, those 20 to 40 kg are given 125 mg po once/day, and those > 40 kg are given 250 mg po once/day. An imidazole or ciclopirox cream should 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/wk. Children may attend school during treatment.
Adults are treated with terbinafine 250 mg po once/day for 2 to 4 wk, which is more effective for endothrix infections, or itraconazole 200 mg once/day for 2 to 4 wk or 200 mg bid for 1 wk, followed by 3 wk without the drug (pulsed) for 2 to 3 mo.
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 po once/day (1 mg/kg for children) and tapering the dose over 2 wk.
Last full review/revision March 2013 by Denise M Aaron, MD
Content last modified November 2013