June 2006

This 9-year-old girl came to the office in a wheelchair because she was having difficulty walking.

She had a five-year history of scale in the toe web spaces, which had not been treated. She has had whitish discoloration of her nails. In the past week, she developed “weeping” between her toes and developed pain and swelling of her feet such that she has not been able to attend school.

What is her diagnosis?

Answer

This girl has a secondary bacterial infection with longstanding tinea pedis (aka athlete’s foot).

Tinea pedis is uncommon in prepubertal children, but can occur.

When it does occur, there is usually a positive history in the family of an adult with tinea pedis. Tinea pedis is less common in societies where shoes are not worn.

Clinically, children with tinea pedis will have scale in the toe web spaces and occasionally fissures, especially the fourth toe web space. Vesicular lesions are somewhat rare in children. Itching can accompany the infection. Over a period of months, the untreated tinea pedis may progress to tinea unguium (dermatophyte infection of the nails), which had occurred in this patient. Secondary bacterial infections can be superimposed on tinea pedis. Because of the warm, moist environment of shoes, gram-negative bacteria are typically the culprits.

Differential diagnoses includes:

• atopic dermatitis. This condition tends to affect the extensor surfaces of the toes-less often the toe web spaces;
• scabies. This condition will be present also on the hands and other areas of the body and burrows can be seen;
• psoriasis. This condition can have similar clinical findings, but tends to also involve the elbows, knees and genital area;
• dyshidrotic eczema of the foot. This condition will more consistently have vesicular lesions;
• contact dermatitis. This condition will affect the dorsal foot and extensor surfaces of the toes with sparing of the sole; or
• candidiasis of the toe webs. This condition may look similar to tinea, but will not have exudates as profuse as this patient has.

Diagnosis can be made based on clinical findings, KOH preparation, or dermatophyte culture. The etiologic agent is most often Trichophyton rubrum, but tinea pedis can also be caused by T mentagrophtes and Epidermophyton floccosum.

Source: Patricia A. Treadwell, MD

Treatment consists of acetic acid or vinegar water soaks twice daily for the gram-negative bacteria. The feet should be kept as dry as possible. Physicians should recommend cotton socks, which should be changed frequently. Milder cases of tinea pedis will respond to topical anti-fungal treatment. Tinea unguium is treated with fluconazole, itraconazole, or terbinafine.

For more information:

• Crawford F. Athlete’s foot. Clin Evid. 2004;12:2266-2270.
• Ecemis T, et al. The necessity of culture for the diagnosis of tinea pedis. Am J Med Sci. 2006;331:88-90.
• Gupta, AK, et al. Dermatophytosis: the management of fungal infections. Skin med. 2005;4:305-310.
• Neri I, et al. Bullous tinea pedis in two children. Mycoses. 2004;47:475-478.