Nummular dermatitis: This skin problem often causes coin-shaped rashes on the skin that can itch or burn.
Also called discoid eczema
People who get this skin problem often see distinct, coin-shaped (nummular) or oval sores on their skin. Nummular dermatitis often appears after a skin injury, such as a burn, abrasion (from friction), or insect bite. A person may see 1 or many patches. These patches can last for weeks or months.
Your dermatologist may refer to this skin condition as:
Men get nummular dermatitis more often than women get it. Men often have their first outbreak between 55 and 65 years of age. When women get it, they are usually younger. They tend to be teenagers or young adults.
Image used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.
Nummular dermatitis: A patch of nummular dermatitis on a patient's ankle.
Patches on the skin tend to begin as a group of tiny, reddish spots and blister-like sores that weep fluid. Then the sores enlarge and grow together to form a coin-shaped patch.
The patches tend to have these signs and symptoms:
A yellowish crust may develop on the patches if a Staphylococcus aureus (staph) infection occurs. This may require treatment with an antibiotic.
The skin between the patches often remains clear, but it can be dry and easily irritated.
Images used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.
Nummular dermatitis: Blisters can form and grow together to create red patches.
This skin problem is more common in men than in women. Men tend to have their first outbreak between 55 and 65 years of age. Women are more likely to get it between the ages of 15 and 25 years. It is rare in children.
While the cause is unknown, researchers think that sensitivity plays a role in some cases. A person may be sensitive to:
If the person has a sensitivity to something, the skin will only clear when the person avoids that substance.
Research also suggests that your risk of getting nummular dermatitis increases if you live in a cold, dry climate or have:
Dermatologists often diagnose nummular dermatitis by looking at the patient’s skin. During the exam, the dermatologist may swab the sores if the doctor thinks you have a skin infection.
If your dermatologist thinks you have an allergy, patch testing (skin tests to find allergies) may be recommended. Your dermatologist also may recommend patch testing if treatment does not fully clear your skin. An allergy can prevent the skin from clearing.
These sores can be stubborn, so seeing a dermatologist for treatment is recommended. Treatment for nummular dermatitis consists of the following:
If you have a bad case or widespread nummular dermatitis, you may need:
With proper treatment, nummular dermatitis can clear completely. Sores on the thighs, legs, and feet often take longer to heal and tend to leave behind darker or lighter spots.
Some patients’ skin clears within a year. Others have these patches for many years. Sometimes the patches go away and then return. Patches that return after clearing tend to appear in the same place as the first outbreak.
To prevent nummular dermatitis from returning once your skin clears, dermatologists recommend the following: