1. Has the patient received a patch test?
2. Contact dermatitis
3. Atopic eczema, Raynaud’s disease and pitted keratolysis
4. The rash is symmetrical.
5. Avoiding shoes with allergens, wet dressings, systemic steroids, topical steroids and/or use of coal tar and emollients
When A Patient Presents With Symmetrical Lesions On The Toes
A 32-year-old Caucasian female presents to the office with swollen, sore, irritated, itchy toes of both feet and a symmetrical distribution on the tops of the toes.
She notes that the redness started four weeks ago. It was on the third toe initially but is now on other toes as well, according to the patient. There is no scaling or maceration in the interspaces, and no scaling on the rest of the foot.
The patient has a history of vaginal infections and had been taking fluconazole (Diflucan, Pfizer) approximately one month prior to her presentation. She has also been taking amitriptyline (Elavil, AstraZeneca) for pubic-related pain. She has sensitive skin as well as a history of hay fever. She denied being labeled as atopic, which refers to diseases that are hereditary and often occur together (asthma and atopic dermatitis).
The patient has no history of eczema or psoriasis. She has been using over-the-counter antifungals on the toes as recommended by her internist with no resolution of the rash. The patient presented in stylish leather shoes with the leather over the toes only. She says she rarely wears socks and only wears sneakers on the weekend.
What You Should Know About Contact Dermatitis
Using patch testing, I diagnosed the patient with allergic contact dermatitis to butylphenol formaldehyde resin in the leather upper portion of her shoes. I prescribed topical corticosteroids for two weeks and the dermatitis on her toes improved significantly after she stopped wearing her leather shoes completely for one month. She wore canvas shoes and wood clogs during that time period.
Contact dermatitis is an acute inflammatory reaction caused by a substance in contact with the skin. There are irritant and allergic types. Irritant dermatitis occurs when a substance causes direct damage to the skin. Allergic contact dermatitis occurs when a substance that serves as an allergen elicits a type IV cell-mediated hypersensitivity reaction.1
Shoe contact dermatitis occurs in a small percentage of the population and is caused by an allergic reaction to a substance in the shoe. The most common causes are dyes, leather, shoe rubber, adhesives, trim and biocides (the pesticides used on the rawhides to kill organisms). Bear in mind that topical medications, steroids, antifungals, antibiotics (neosporin), bag balm, botanicals and socks may cause allergic reactions that may masquerade as shoe contact dermatitis.2 It is important to look at both feet to see if the rash is symmetrical.
The most common shoe allergens are rubber, chromate and butylphenol formaldehyde resin (see “A Guide To Common Shoe Allergens” above).
Along with the fact that patients often wear footwear without socks during all months of the year, the moisture and humidity in shoes increases skin contact with allergens.
Most patients with shoe dermatitis have hyperhidrosis and many are atopic. One should consider shoe dermatitis in both children and adults with foot eczema.
The pattern of shoe dermatitis usually corresponds to the location of the offending substance in the shoe. Dorsal foot shoe dermatitis has been attributed to allergens in glues as well as chromates and vegetable tannins in leather. Plantar shoe dermatitis may be due to rubber or other materials.
Sole involvement tends to spare the instep and toes’ flexural creases. Shoe dermatitis is usually symmetrical but may also be patchy or unilateral. Classically, allergic contact dermatitis to shoes manifests as a rash on the dorsum of the feet or toes. However, a subset may only have involvement on the soles of the feet. One author explains that the culprit was the neoprene glues contained in the orthotics that patients wore.5 Patients will routinely wear orthotics in their shoes without socks. In the end, one has to be a detective to determine the cause of the rash or dermatoses.
What You Should Consider In The Differential Diagnosis