Practice recommendations
- Potassium hydroxide preparation should be used as an aid to diagnosis for all erythrosquamous lesions (B).
- Fungal culture should be used in cases in which history, physical examination, and potassium hydroxide preparation fail to clearly exclude a diagnosis of tinea (B).
- Short-duration topical therapy with terbinafine, naftifine, and butenafine is efficacious for most epidermal tinea infections (A).
- Oral antifungal agents are important in the treatment of tinea infections thatare widespread, fail to respond to topical treatment, involve the thick stratum corneum of the soles and palms, or occur in immunosuppressed patients.
- Short courses of oral itraconazole and terbinafine are safe and effective in treating tinea infections (A).
Though findings on history and physical examination are sometimes sufficient to make a diagnosis of tinea infection, a potassium hydroxide (KOH) study usually is required for confirmation. Even the KOH study can be misleading, however, if a patient recently self-administered a topical antifungal agent. This article describes the varying appearance of tinea infections according to their anatomic location, and outlines a careful work-up.
Highly effective and affordable over-the-counter medications have proliferated, and short-course therapy is available. Based on systematic reviews of randomized, controlled studies, it is possible to recommend specific first-line therapies for tinea infections.
Manifestations of tinea infection
Clinical manifestations of tinea vary with anatomic location, duration of infection, and pathogen. In general, zoophilic dermatophytes evoke a more vigorous host response than the anthropophilic species.5 Shared features of many dermatophyte infections include erythema, scaling, pruritus, ring formation, and central clearing of lesions. Table 1 reviews published data on the diagnostic value of selected clinical signs in suspected tinea infection.6
TABLE 1
Diagnostic value of selected signs and symptoms in tinea infection
| Sign/symptom | Sensitivity | Specificity | PV+ | PV– | LR+ | LR– |
|---|---|---|---|---|---|---|
| Scaling | 77% | 20% | 17% | 80% | 0.96 | 1.15 |
| Erythema | 69% | 31% | 18% | 83% | 1.00 | 1.00 |
| Pruritus | 54% | 40% | 16% | 80% | 0.90 | 1.15 |
| Central clearing | 42% | 65% | 20% | 84% | 1.20 | 0.89 |
| Concentric rings | 27% | 80% | 23% | 84% | 1.35 | 0.91 |
| Maceration | 27% | 84% | 26% | 84% | 1.69 | 0.87 |
| Note: Signs and symptoms were compiled by 27 general practitioners prior to submission of skin for fungal culture. Specimens were taken from 148 consecutive patients with erythematosquamous lesions of glabrous skin. Culture results were considered the gold standard. | ||||||
| PV+, positive predictive value; PV–, negative predictive value; LR+, positive likelihood ratio; LR–, negative likelihood ratio. | ||||||
| Adapted from Lousbergh et al, Fam Pract 1999; 16:611–615.6 | ||||||
| Level of evidence=2b. For an explanation of levels of evidence, see page 865. | ||||||
Tinea pedis
Tinea of the foot may manifest as interdigital, plantar, or acute vesicular disease. Toe webs and soles of the feet are the sites most commonly affected. Tinea pedis occurs most commonly in postpubertal adolescents and adults, but may be seen in children.7
With interdigital infection, toe webs may become scaly, pruritic, and fissured. Interaction of bacteria and infecting dermatophytes may lead to a white, soggy maceration.8 Extension from the web space to the dorsal or plantar surface commonly occurs.
In chronic plantar or moccasin-type tinea pedis, the entire surface of the sole may be covered with fine, white scale and may assume a hyperkeratotic appearance. Chronic web infection may lead to acute inflammation characterized by vesicles, pustules, and bullae over the sole or the dorsum of the foot.5
Differential diagnosis. The differential diagnosis includes dry skin, pitted keratolysis, erythrasma, and contact dermatitis. Some conditions may appear very similar to tinea pedis, increasing the importance of KOH prep and fungal culture.
Tinea pedis may be distinguished from erythrasma by lack of bright coral appearance when examined with a Wood’s lamp. Tinea pedis infections also lack the well-demarcated erosions, or pits, of pitted keratolysis. Evidence of concurrent onychomycosis should increase the suspicion that tinea pedis is the correct diagnosis.
Tinea manuum
Tinea of the hand is usually analogous to moccasin-type tinea pedis. The palm appears hyperkeratotic and has very fine white scale that emphasizes the normal lines of the hand. Tinea of the dorsal surface of the hand usually occurs in the classic ringworm pattern. Tinea manuum is often seen in association with tinea pedis and onychomycosis. Many clinicians are familiar with the “one hand, two feet” syndrome, in which the palmar surfaces of both feet and one hand are infected (Figure 1).9 Onychomycosis often occurs in association with this presentation of tinea.
Differential diagnosis. The pattern of tinea manuum may be confused with those of eczema, contact dermatitis, palmar psoriasis, or even normal, rough hands. Unilateral involvement, presence of fingernail onychomycosis, lack of history indicating irritant or allergen exposure, and absence of psoriatic nail changes should increase the suspicion of palmar tinea manuum.
FIGURE 1
Tinea pedis
The common “1 hand, 2 feet” syndrome of tinea pedis. This syndrome usually requires systemic therapy.
Tinea cruris
Tinea of the groin is most common in adult males and is promoted by a warm, moist environment. Tinea cruris begins in the crural fold and spreads onto the thigh. The interior portion of the lesion is usually erythematous or slightly brown in light-skinned individuals. The leading edge often advances in a sharply demarcated semicircle with a raised, slightly scaling border. The lesion is most often bilateral, sparing the skin of the scrotum. Pruritus is common and increases as sweat macerates the irritated skin.