Several techniques are available to confirm the diagnosis of tinea infections. These include:
- Potassium hydroxide (KOH) examination. In the presence of a tinea infection, a KOH preparation of scale scraped from a lesion-particularly the active border-will reveal fun- gal elements when examined under a microscope.
- Culture. A culture may be warranted when a fungal infection is strongly suspected despite a negative KOH result. Unfortunately, dermatophyte cultures can take from 4 to 6 weeks to become positive; therefore, treatment decisions may have to be made before culture findings are reported.
- Histopathologic examination with periodic acid–Schiff stain. This stain is used to identify fungi within material from a skin biopsy or nail clippings.
Topical therapy. A topical antifungal medication is the initial thera- py for tinea cruris, tinea corporis, tin- ea pedis, and tinea manuum. These agents are available in various preparations, including creams, gels, and lotions. Generally, lotions are preferable for use on hair-bearing areas.
Systemic therapy. Tinea capitis, extensive tinea corporis, and tinea unguium are best treated initially with oral antifungal agents, because these infections usually do not respond to topical therapy. Griseofulvin, itraconazole, and terbinafine are among the frequently prescribed systemic antifungal drugs (Table). Patients with tinea unguium who have been treated sucessfully with systemic antifungal agents are often given topical antifungal preparations to prevent recurrences.
In general, tinea corporis and tinea capitis do not recur after effective treatment, unless the patient is reinfected by a family member or by a contact who still has the infection. In contrast, tinea pedis, tinea cruris, and tinea unguium frequently recur. The use of absorbent powders and prophylactic topical therapy after a course of systemic therapy has been completed can help prevent recurrences.
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