Tinea Manuum & Tinea Pedis (Dermatophytosis, Tinea of Palms & Soles, “Athlete's Foot”)

ESSENTIALS OF DIAGNOSIS
Most often presenting with asymptomatic scaling.
May progress to fissuring or maceration in toe web spaces.
Itching, burning, and stinging of interdigital web; scaling palms, and soles; vesicles of soles in inflammatory cases.
The fungus is shown in skin scrapings examined microscopically or by culture of scrapings.
General Considerations
Tinea of the feet is an extremely common acute or chronic dermatosis. Certain individuals appear to be more susceptible than others. Most infections are caused by Trichophyton species.
Clinical Findings
A. SYMPTOMS AND SIGNS
The presenting symptom may be itching, burning, or stinging. Pain may indicate secondary infection with complicating cellulitis. Interdigital tinea pedis is the most common cause of leg cellulitis in healthy individuals. Tinea pedis has several presentations that vary with the location. On the sole and heel, tinea may appear as chronic noninflammatory scaling, occasionally with thickening and fissuring. This may extend over the sides of the feet in a “moccasin” distribution. The KOH preparation is usually positive. Tinea pedis often appears as a scaling or fissuring of the toe webs, perhaps with sodden maceration. As the web spaces become more macerated, the KOH preparation and fungal culture are less often positive because bacterial species begin to dominate. Finally, there may also be grouped vesicles distributed anywhere on the soles, generalized exfoliation of the skin of the soles, or nail involvement in the form of discoloration and thickening and crumbling of the nail plate.
B. LABORATORY FINDINGS
Hyphae can be demonstrated microscopically in skin scales treated with 10% KOH. KOH and culture does not always demonstrate pathogenic fungi from macerated areas.
Differential Diagnosis
Differentiate from other skin conditions involving the same areas, such as interdigital erythrasma (use Wood's light). Psoriasis may be a cause of chronic scaling on the palms or soles and may cause nail changes. Repeated fungal cultures should be negative, and the condition will not respond to antifungal therapy. Contact dermatitis (from shoes) will often involve the dorsal surfaces and will respond to topical or systemic corticosteroids. Vesicular lesions should be differentiated from pompholyx (dyshidrosis) and scabies by proper scraping of the roofs of individual vesicles. Rarely, gram-negative organisms may cause toe web infections in the setting of prior tinea or in its absence. Culture is not very specific, because gramnegative organisms can be cultured from normal toe webs. This entity is treated with aluminum salts (see below) and imidazole antifungal agents or ciclopirox.
Prevention
The essential factor in prevention is personal hygiene. Wear open-toed sandals if possible. Use of rubber or wooden sandals in community showers and bathing places is often recommended, though the effectiveness of this practice has not been studied. Careful drying between the toes after showering is essential. A hair dryer used on low setting may be used. Socks should be changed frequently, and absorbent nonsynthetic socks are preferred. Apply dusting and drying powders as necessary. The use of powders containing antifungal agents (eg, Zeasorb-AF) or chronic use of antifungal creams may prevent recurrences of tinea pedis.
Treatment
A. LOCAL MEASURES
Macerated stage—Treat with aluminum subacetate solution soaks for 20 minutes twice daily. Broadspectrum antifungal creams and solutions (containing imidazoles or ciclopirox instead of tolnaftate and haloprogin) will help combat diphtheroids and other grampositive organisms present at this stage and alone may be adequate therapy. If topical imidazoles fail, often 1 week of once-daily allylamine treatment (terbinafine or butenafine) will result in clearing.
Dry and scaly stage—Use any of the agents listed in the section on tinea corporis. The addition of urea 10% lotion or cream may increase the efficacy of topical treatments in thick (“moccasin”) tinea of the soles.
B. SYSTEMIC MEASURES
Griseofulvin should be used only for severe cases or those recalcitrant to topical therapy. If the infection is cleared by systemic therapy, the patient should be encouraged to begin maintenance with topical therapy, since recurrence is common. Itraconazole, 200 mg daily for 2 weeks or 400 mg daily for 1 week, or terbinafine, 250 mg daily for 2–4 weeks, may be used in refractory cases.
Prognosis
For many individuals, tinea pedis is a chronic affliction, temporarily cleared by therapy only to recur.

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