The FP noted patchy alopecia with scaling of the scalp and made the presumptive diagnosis of tinea capitis. A woods lamp examination did not demonstrate fluorescence. The child was very cooperative and the doctor was able to perform a potassium hydroxide (KOH) preparation by scraping the areas of alopecia with the edge of one glass slide while catching the scale on another slide. Microscopic examination revealed branching hyphae and some broken hairs with fungal elements within the hair shaft. (See video on how to perform a KOH preparation.) This microscopic picture was consistent with Trichophyton tonsurans, the most common cause of tinea capitis in the United States. The reason that the infected area did not fluoresce was that the dermatophyte was within the hair shaft (endothrix) rather than external to the hair (exothrix).
Topical antifungal therapy is not adequate for tinea capitis; oral treatment is needed. Oral antifungal choices include griseofulvin, terbinafine, and fluconazole. Griseofulvin comes in an oral suspension making it a desirable option for children who can’t swallow pills. However, at least 6 to 8 weeks of treatment (20 mg/kg/d) is required. Oral terbinafine tablets are less expensive and shorter courses of therapy may be used. Tablets of 250 mg terbinafine (most affordable of all the choices) can be broken in half for younger children and the dose should always be calculated based on weight. Fluconazole comes in various tablets, strengths, and liquid formulations and can be prescribed for 3 to 6 weeks, as needed.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R, Yao C. Tinea capitis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill;2013:782-787.
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