When A Patient Presents With Symmetrical Lesions On The Toes

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Key Questions To Consider

1. What essential questions does one still need to ask to help make the diagnosis? 2. What is the tentative diagnosis?
3. Can you list at least three differential diagnoses?
4. What features of this condition differentiate it from other conditions in your differential?
5. What is the suitable treatment of this condition?

Author(s): 
By M. Joel Morse, DPM

Nummular eczema. These lesions are usually round and coin-shaped. They are not generalized lesions. The patient has no history of exposure to an allergen.
Atopic eczema. Patients have a chronic rash with flexural distribution.
Dermatitis herpetiformis. The rash is localized to elbows and knees.
Scabies. One may see this in other family members. It is localized to the dorsum of feet and ankles, and spreads to other areas. Skin scraping is positive.
Tinea pedis (inflammatory). This includes itching and maceration between toes, which was not present in the patient. Pitted keratolysis. This bacterial disease is due to hyperhidrosis of the stratum corneum. There is little inflammation and distinct pits are noted.
Pustular psoriasis. This is usually not symmetrical and on a larger area.
Lichen planus. Patients have purple flat, topped bumps that are itchy. This was not present in the patient.
Atopic dermatitis. One usually sees this condition among younger patients and on plantar skin as well. In the absence of an allergen in this case, atopic dermatitis would be a possible diagnosis.
Raynaud’s disease. A spasm of blood vessels causes a change in color. The three-phase color sequence is white to blue to red.
Mechanical irritant dermatitis. This results from abnormal foot mechanics.
Exanthematous drug eruption. The rash could be due to the fluconazole but these rashes normally start on the trunk and are not usually symmetrical.

A Guide To Clinical Manifestations And Diagnostic Testing

The patient may have a rash ranging from a mild itch to severe itching. One may also see inflammation, swelling, redness, blisters (crusts and scales, which are old blisters), fissuring, burning, pain or swelling. In severe cases, open sores can result in bacterial skin infections.
With long-term exposure to an allergen, the skin can become lichenified. Usually, the involved areas are on the tops of the foot and toes. However, contact dermatitis can also affect the sole of the foot, the legs and the sides of the feet and heels. The area in between the toes is not usually affected.
One should perform patch testing to discover and/or confirm a contact allergy. Patch testing does not diagnose contact dermatitis. People with a contact allergy develop dermatitis to substances.
Many companies provide the patch test kits that have the allergens in them already. The Thin-Layer Rapid Use Epicutaneous Test®, also known as the T.R.U.E. Test (Allerderm), is a convenient, ready-to-use patch. It is recommended that one seek out a physician who has had experience in administering and reading the test. If commercial patches and tape are not available, one may improvise by using Band Aids as patches with occlusive tape over the Band Aid. The allergen must be 1.0 cm2 of surface area and it goes under the Band Aid.4

Inside Insights On Treatment

One can treat acute contact dermatitis with wet dressings of Burrow’s solution or diluted vinegar; short courses of systemic steroids; short or prolonged treatment with topical steroids; and/or coal tar and emollients. Patients also must wear shoes that are free of the causative allergens.
If the patient cannot find an allergen-free shoe to wear and wants to try wearing regular shoes, Storrs suggests the following preventative measures.
• Decrease the risk of hyperhidrosis with tea soaks or Drysol.
• Buy all new socks as socks absorb allergens.
• Use insoles of cork or piano felt over the plantar foot bed if necessary.
• Try corticosteroid spray (Kenalog) before the use of “potential problematic shoes.” Keep in mind that this is not a long-term solution.
• Wear shoes made of wood or plastic, all sewn shoes made of leather or Birkenstock sandals.2

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