What causes this foot rash in children?

IN THE summer months, children who wear occlusive, tennis shoe-like footwear and whose feet sweat excessively, can present with this rash.

It involves the forefoot and sometimes the heels, but spares the instep. It also spares the deep web spaces between the toes.

It is known as juvenile forefoot dermatitis. It was first reported in the late sixties and may have been related to changing fashions in footwear and socks. 

Histology shows an eczema and a blocking of sweat glands. Sometimes the tips