Nummular Eczema: Don't Mistake it for a Fungal Infection

February 1, 2005
Joe Monroe, PA-C
Joe Monroe, PA-C

The multiple, uniformly scaly, coin-shaped, papulosquamous lesions shown here on the lower leg of a 61-year-old man had persisted for 3 months despite application of topical clotrimazole and 1% hydrocortisone. The rash involved only the legs and was variably pruritic. The patient had a long history of dry skin.

The multiple, uniformly scaly, coin-shaped, papulosquamous lesions shown here on the lower leg of a 61-year-old man had persisted for 3 months despite application of topical clotrimazole and 1% hydrocortisone. The rash involved only the legs and was variably pruritic. The patient had a long history of dry skin. Recently, he had begun to swim daily for exercise. Every day, he took long, hot showers and used highly perfumed bar soap. A potassium hydroxide preparation of scrapings from the lesions was negative for fungal elements. Joe Monroe, PA-C, of Tulsa, Okla, writes that these lesions are highly characteristic of nummular eczema-a reaction associated with dry skin that may be aggravated by soaps, frequent bathing, allergies, and certain medications. Exposure to winter weather and regular use of a hot tub are also well-known triggers. This rash is common, but it is frequently misdiagnosed as a “fungal infection.” Affected patients are often given multiple courses of antifungal therapy without success and are then referred to a dermatologist. Nummular eczema primarily occurs in middle-aged and elderly persons; the cause is unknown. The dorsum of the hand is the most commonly involved site; other frequently involved areas include the extensor aspects of the forearms, lower legs, flanks, and hips. The course is variable, but it is usually chronic.1 Besides tinea, the differential diagnosis includes psoriasis, Bowen disease, and discoid lupus erythematosus (DLE). Psoriasis usually involves additional areas, such as the elbows and knees; patients often have a history of psoriatic eruptions. Bowen disease typically appears as a fixed, solitary lesion on sun-damaged skin. DLE is almost always triggered by sun exposure; the annular lesions have central clearing. Treatment of nummular eczema involves adequate skin moisturizing; use of nonirritating soaps; and reduced temperature, length, and frequency of showers and baths. The application of mid- to high-potency topical corticosteroid ointments may hasten resolution. Failure of this treatment indicates the need for a biopsy. This patient was successfully treated with clobetasol ointment.

References:

REFERENCE:
1.

Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. Philadelphia: Mosby;2004:61.