Answer to last month's Clinical Quiz

Question:

The parents of a nine-year-old boy brought your attention to a rash at the plantar aspect of both forefeet. The rash was present for a year and caused only slight discomfort. The toe webs were spared. He was otherwise well. He enjoyed sports and frequently wore track shoes.

Answer:

B. Juvenile plantar dermatosis

The child had juvenile plantar dermatosis. It mainly occurs in children aged 3 to 14 years. The forefoot plantar skin is red and glazed, sometimes with cracks. It tends to involve the weight-bearing areas of the feet symmetrically, like the balls (first metatarsal heads) of the feet and toe pads. It spares the insteps and toe webs, thus distinguishing it from tinea pedis. It can be asymptomatic or sometimes painful.

This condition is believed to be due to a trend of replacing natural materials (e.g. cotton, wool and leather) of footwear by synthetic materials like plastics and nylon. The latter are generally less porous. Their occlusion effect is increased by the repellent coatings applied to shoes to enhance their durability. Many of these affected children wear track or trainer shoes for long hours and are keen on sports. It is therefore postulated that the hot and humid condition created by these footwear, together with friction and sweating sustained by the feet, may result in the condition.

This diagnosis can be made clinically, though skin scraping to exclude fungal infection and patch testing to exclude contact dermatitis are sometimes performed. The affected child should be advised to use 100% cotton socks, leather shoes while outdoor, and sandals while indoor. Nevertheless these do not necessarily result in a cure. Topical steroids may have some initial benefits and emollients are often prescribed. Fortunately most patients will improve as they enter adolescence.