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There is a good chance that you know someone who has eczema—approximately 1 in 10 Americans have some type of eczema (Silverberg, 2013).
In dermatology, eczema is a term used to describe a family of skin conditions that cause inflamed, irritated skin. There are different types of eczema, and nummular eczema is a member of this family. In this article, we’ll examine the ins and outs of nummular eczema and give you some potential treatment options if you have it.
What is nummular eczema?
Nummular means “coin-shaped” in Latin—not surprisingly, nummular eczema (or dermatitis) is sometimes called discoid eczema. People with nummular eczema may see round or oval (coin-shaped) patches of red, itching (or sometimes burning) skin, often in areas of prior skin injury (like burns, scrapes, scratches, or insect bites) (AAD, n.d.).
While these patches most often appear on the legs, they can also show up on your arms, hands, torso, and feet. The size can vary as well—nummular eczema patches can range from smaller than one inch to larger than four inches. The patches start as groups of tiny, red spots and blister-like sores. They then get bigger and merge, forming the round patch characteristic of nummular eczema. This eczema type is most common in men aged 55–65, but it can occur at any age (AAD, n.d.).
Signs and symptoms of nummular eczema may include (AAD, n.d.):
- Pink, red, or brownish round patches with defined edges on your legs, arms, hands, feet, and torso
- Itching (pruritic) and/or burning skin
- Blister-like sores that ooze, leading to crusting and eventual scaling
- Yellow crusting from overlying skin infection with Staphylococcus aureus, a common skin bacteria
Between the eczema patches, the skin is generally clear; it may be dry or easily irritated. Nummular eczema often comes and goes—days or months after your patches have gone away, they can flare up again, or new lesions can form nearby (Zirwas, 2020).
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Causes of nummular eczema
Scientists don’t know the exact cause of nummular eczema; however, several factors may play a role or increase the likelihood of developing this skin condition.
For example, people with nummular eczema also have a history of other types of eczema, asthma, or allergies (Medline, 2019). Skin sensitivity, especially to things like formaldehyde and metals (like nickel), may trigger eczema. Certain medications that you put on your skin, like neomycin, could also lead to skin sensitivity and nummular eczema (AAD, n.d.). Very dry skin and decreased skin oil production may contribute to developing this condition (Zirwas, 2020).
Other factors that increase the risk of nummular eczema include (AAD, n.d):
- Certain medications, like isotretinoin (brand name Accutane) and interferon (used for cancers and some viral infections)
- Living in a cold, dry climate
- Very dry skin (xerosis)
- Skin injury, like scrapes, bug bites, chemical burns, etc.
- Bacterial skin infection
- Poor blood flow and/or swelling in the legs
Stress is another potential risk factor for nummular eczema (Medline, 2019).
How is nummular eczema diagnosed?
Most of the time, your dermatologist or healthcare provider can diagnose your nummular eczema just by looking at your skin. However, if the affected areas look suspicious for bacterial infection, you may need skin swabs of your sores. Patch testing can also be helpful, especially if your provider is concerned about allergic contact dermatitis or skin sensitivity.
Other skin conditions can look like nummular eczema, including (Zirwas, 2020):
- Atopic dermatitis, a form of eczema
- Allergic contact dermatitis, a form of eczema
- Tinea corporis (ringworm), a fungal skin infection with ring-like lesions, diagnosed by looking at skin scrapings stained with potassium hydroxide (KOH prep) under the microscope
- Stasis dermatitis, a skin condition due to poor blood circulation
- Psoriasis, a dry, scaly skin condition sometimes accompanied by itching
- Bullous pemphigoid, characterized by skin blisters; may see itchy eczematous lesions before blisters form
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How is nummular eczema treated?
An important part of treating nummular eczema is taking good care of your skin. Taking steps to combat skin dryness and decrease your exposure to skin irritants can go a long way in improving your skin’s health (AAD, n.d.).
- Bathe in lukewarm water, not hot water, and use mild cleansers.
- Apply skin moisturizers at least twice daily and especially after bathing.
- Protect your skin from skin injuries, like scrapes, scratches, cuts, insect bites, etc.
- Avoid contact with rough clothing (like wool). Instead, wear soft, breathable fabrics.
- Having a humidifier at home may help prevent your skin from drying out.
These strategies may not be enough to treat all cases of nummular eczema. While there is no cure, there are effective ways to control and improve your symptoms.
High-dose prescription topical corticosteroid creams may be applied to the affected areas 1–2 times a day for 2–4 weeks or until your lesions resolve. If topical steroids don’t help, you may benefit from phototherapy or light therapy. Phototherapy may involve shining narrow-band ultraviolet B light (NBUVB) on your lesions or even sitting in natural sunlight for 10–30 minutes a day. Phototherapy may increase your risk of skin cancer, so get medical advice before starting this type of treatment (Zirwas, 2020).
A small portion of people with nummular eczema may need treatment with oral medications, like prednisone, methotrexate, or cyclosporine. Since these are systemic drugs, they have a higher likelihood of side effects than topical therapies (Zirwas, 2020).
If you think you may have nummular eczema, see your healthcare provider for medical advice on how to treat and prevent symptoms.
- American Academy of Dermatology (AAD) – Eczema Resource Center- Nummular Dermatitis, (n.d.). Retrieved on Jan 25, 2021 from https://www.aad.org/public/diseases/eczema/types/nummular-dermatitis
- MedlinePlus – Nummular eczema (2019). Retrieved on Jan 25, 2021 from https://medlineplus.gov/ency/article/000870.htm
- Silverberg, J. I., & Hanifin, J. M. (2013). Adult eczema prevalence and associations with asthma and other health and demographic factors: A US population–based study. Journal of Allergy and Clinical Immunology, 132(5), 1132–1138. https://www.jacionline.org/article/S0091-6749(13)01366-3/fulltext
- Zirwas, M.J. (2020). UpToDate – Nummular eczema. Retrieved on Jan 25, 2021 from https://www.uptodate.com/contents/nummular-eczema
Dr. Mike is a licensed physician and the Director, Medical Content & Education at Ro.