A 38-year-old man presents with an itchy rash on his hands and blisters on his feet for 1 week duration (Figure 140-1). Vesicular tinea pedis with bullae were present. The papules and vesicles between the fingers were typical of an autoeczematization reaction (Id reaction) (Figure 140-2). The patient was treated with an oral antifungal medication and a short burst of oral prednisone for the autosensitization reaction.

Tinea pedis is a common cutaneous infection of the feet caused by dermatophyte fungus. The clinical manifestation presents in 1 of 3 major patterns: interdigital, moccasin, and inflammatory. Concurrent fungal infection of the nails (onychomycosis) occurs frequently.

Athlete’s foot

• Tinea pedis is thought to be the world’s most common dermatophytosis.1
  
• 70% of the population will be infected with tinea pedis at some time.1
  
• More commonly affects males than females.1
  
• Prevalence increases with age and it is rare before adolescence.1

• A cutaneous fungal infection most commonly caused by Trichophyton rubrum.1
  
• Trichophyton mentagrophytes and Epidermophyton floccosum follow in that order.
  
• T. rubrum causes most tinea pedis and onychomycosis.

• Male gender.
  
• Use of public showers, baths or pools.2
  
• Household member with tinea pedis infection.2
  
• Certain occupations (miners, farmers, soldiers, meat factory workers, marathon runners).2
  
• Use of immunosuppressive drugs.

Typical Distribution and Morphology

Three types of tinea pedis

• Interdigital type—most common (Figure 140-3).
  
• Moccasin type (Figure 140-4 and 140-5).
  
• Inflammatory/vesicular type—least common (Figure 140-1).

Some authors describe an ulcerative type (Figure 140-6).

Clinical Features

• Interdigital—white or green fungal growth between toes with erythema, maceration, cracks, and fissures—especially between fourth and fifth digits (Figure 140-3). The dry type has more scale and the moist type becomes macerated.
  
• Moccasin—scale on sides and soles of feet (Figure 140-4 and 140-5).
  
• Vesicular—vesicles and bullae on feet (Figure 140-6).
  
• Ulcerative tinea pedis is characterized by rapidly spreading vesiculopustular lesions, ulcers, and erosions, typically in the web spaces (Figure 140-7). It is accompanied by a secondary bacterial infection. This can lead to cellulitis or lymphangitis.
  
• Autosensitization (dermatophytid reaction; ID reaction) is a hypersensitivity response to the fungal infection causing papules on the hands (Figure 140-2).
  
• Examine nails for evidence of onychomycosis—fungal infections of nails may include subungual keratosis, yellow or white discolorations, dysmorphic nails (Chapter 193, Onychomycosis).
  
• Examine to exclude cellulitis that may show erythema, swelling, tenderness with red streaks tracking up the foot and lower leg (Chapter 120, Cellulitis).

Typical Distribution

Between the toes, on the soles, and lateral aspects of the feet.

Laboratory Studies