Nummular eczema, also known as discoid eczema, can occur at any age but is typically seen in individuals over 50 years old and is more common in men. The condition is not dangerous and is not associated with other systemic diseases.
Itch is the most bothersome symptom of the condition. The rash appears as red patches, which may appear brown in individuals with darker skin. The rash is often dry, flaky, but in some cases, it may ooze fluid and form crusts. The shape of the rash is typically round or oval, ranging in size from 1-10 cm. Multiple patches of eczema are usually present on the skin simultaneously. The rash is slightly raised and can sometimes be more active at the edges, resembling a ring. It most commonly appears on the arms and legs but can also occur on the lower torso.
Diagnosis is based on a physical examination by a healthcare professional. In some cases, tests may be conducted to rule out other conditions or assist in treatment. This may include a skin biopsy, where a small sample of the skin is taken for analysis. Allergy tests (patch tests) and bacterial cultures may also be performed.
The cause of nummular eczema can be multifactorial and not always identifiable. Atopic eczema may be a contributing factor, especially if the individual had eczema as a child. Skin injuries and stretching of the skin, such as surgical breast procedures, insect bites, or abrasions, can trigger nummular eczema. Dry skin can also be a cause. Bacterial infection and impetigo can also trigger nummular eczema. Rarely, contact dermatitis from chemicals that come into contact with the skin can be a cause. Varicose veins and leg swelling are also mentioned as possible factors. Medication use and excessive alcohol intake may also play a role.
The primary form of treatment involves moisturizing with emollients and using corticosteroid creams. Emollients should be applied both to the affected rash and the surrounding normal skin to prevent new rashes. Creams and ointments are preferable to lotions.
Corticosteroid creams are used daily on the rash for specific periods. These are prescription medications, and the usage should be tailored to the individual. Typically, a potent corticosteroid cream is used daily for 2-4 weeks, followed by less frequent application every second or third day. If regular application of corticosteroid cream does not provide relief, occlusion therapy may be considered. This involves applying corticosteroid to the skin and then covering it with artificial skin (Duoderm) or a dressing for several days. This allows the corticosteroid to penetrate deeper into the skin and be more effective.
Other treatments that may be considered include light therapy, oral antibiotics, and immunosuppressive medications (such asmethotrexate, prednisolone, and cyclosporine). Treating nummular eczema can be challenging, and unfortunately, the condition can have a prolonged course. Treatment often requires significant effort from the patient.
Nummular eczema can resemble other skin conditions such as other types of eczema (atopic eczema, stasis dermatitis), fungal infections, and psoriasis.
