How do you explain this persistent, pruritic rash?

A 16-year-old boy joined the soccer team about 1 month earlier. Shortly thereafter, a persistent, pruritic rash developed on the dorsa of his feet. 

What is your clinical impression?

A. Contact dermatitis to soccer shoes.
B. Dermatophyte infection.
C. Sweaty foot syndrome.
D. Psoriasis.
E. Dyshidrosis.

Answer: Contact dermatitis

Pitting of the toenails was noted, which suggested a psoriatic diathesis, D, that contributed to the skin manifestations of contact dermatitis to the soccer shoes, A. Contact dermatitis usually affects the dorsa of the feet, whereas dermatophyte infections commonly cause eruptions on the soles. If in doubt, a potassium hydroxide evaluation will rule out a dermatophyte infection. Dyshidrosis occurs on the toes and sides of the soles—not on the dorsa. Although sweaty feet can aggravate contact dermatitis, changing socks and using foot powder would not be helpful in this case.