A pruritic rash developed on the feet of a 40-year-old woman 2 days after she had worn a new pair of shoes for a few hours. The erythematous, papular, scaly eruption was more prominent on the right foot. Dr Sunita Puri of Decatur, Ala, diagnosed shoe dermatitis, a T-cell—mediated immune reaction to an antigen that comes in contact with the skin. Severe cases may involve crusting or weeping. The interdigital spaces are spared; keratotic changes may affect the plantar surface, which is usually free of lesions because of the thickness of the epidermis.
Shoe dermatitis must be differentiated from tinea pedis; the history and the distribution of lesions help make this distinction. A potassium hydroxide preparation of skin scrapings reveals septate hyphae if a dermatophyte infection is present.
Footwear contains potentially irritating and sensitizing agents. When the feet sweat, chemicals in the shoes can leach out. The occlusive effect of the shoes prevents evaporation of moisture and thus increases the percutaneous penetration of these chemicals. Friction and irritation aggravate the condition.
Potassium dichromate in tanned leather is a frequent cause of shoe dermatitis; other culprits include rubber, glue, and other adhesives, and dyes. Patch testing with the most common standardized test allergens and with material taken from the shoes can be helpful.
Advise the patient to avoid wearing shoes whenever possible and to consider alternative footwear such as open sandals, canvas-topped sneakers, or vinyl shoes. This patient's condition responded to wet compresses, topical corticosteroids, and antipruritic agents.