Nummular Dermatitis
Nummular dermatitis, also known as nummular eczema or discoid eczema, is a chronic but treatable condition that causes coin-shaped spots on the skin. The spots are usually very itchy and ooze a clear fluid or become dry and crusty (scabby). This disease usually occurs at ages 55–65 years and is more common in men than women. However, nummular dermatitis can also be found at a younger age or in adolescence, especially in women.
For general information about dermatitis, you can read this article: Dermatitis – Symptoms, Causes, Prevention & Treatment.
Symptoms of Nummular Dermatitis
Symptoms of nummular dermatitis can include:
- Red patches or rashes on the skin that are initially small and appear in groups.
- There are red spots inside the patches and fluid-filled blisters. Later, the skin lesions enlarge to form coins or ovals.
- The diameter of the lesion is 2–10 centimeters.
- The most commonly affected location is the feet, but it can appear on other parts of the body, such as the trunk, arms, hands, and palms.
- Itching can range from mild to severe in intensity and may be accompanied by burning pain.
- Blistering lesions on the skin that can burst, crust over, and over time become scaly.
Causes of Nummular Dermatitis
The exact cause of nummular dermatitis is still unknown. However, dry skin or sensitivity to certain substances has been linked to the occurrence of nummular dermatitis, such as:
- Metals, such as nickel and mercury, are found during dental fillings.
- Formaldehyde.
- Medications, such as neomycin.
Trauma to the skin from insect bites, scratches, or chemical burns can also trigger nummular dermatitis. In addition, this chronic skin condition can also develop as a reaction to other types of eczema and their triggers, such as contact dermatitis and nickel. When it occurs on the legs, it can be associated with poor blood flow in the lower body and stasis dermatitis which can cause circulation problems.
Risk Factors for Nummular Dermatitis
Some risk factors that can increase a person’s risk of developing nummular dermatitis include:
- Very dry skin (xerosis).
- Have a history of other eczema, such as atopic dermatitis or stasis dermatitis.
- Poor blood flow, especially in the legs.
- Injury or irritation to the skin that can be caused by insect bites and exposure to certain chemicals.
- A bacterial skin infection, most commonly caused by Staphylococcus aureus.
- Using certain medications such as isotretinoin (a retinoid).
Nummular Dermatitis Diagnosis
In diagnosing nummular dermatitis, the doctor will ask about symptoms and medical history and look for risk factors. Nummular dermatitis can usually be diagnosed simply by performing a physical examination of the lesions. The doctor will recommend allergy testing to determine whether the skin is allergic to something that can trigger nummular dermatitis.
Other supporting examinations can be performed to help establish the diagnosis; for example, in cases with atypical symptoms or resembling other diseases, a swab of fluid from skin lesions is examined under a microscope to look for bacteria or fungi. A skin biopsy can be performed to rule out other diagnoses with dermatitis-like lesions, such as tinea corporis, psoriasis, and drug-induced skin eruptions.
Nummular Dermatitis Treatment
Treatment for nummular dermatitis is aimed at reducing inflammation and the symptoms of itching or pain that arise. Medications that can be used for nummular dermatitis include:
- Corticosteroids, in the form of ointments or creams, are the primary choice for reducing inflammation in nummular dermatitis.
- The phototherapy commonly used is UVB phototherapy in cases with extensive lesions that do not heal for a long time with topical or ointment treatment. UVA phototherapy with psoralen can also be used in severe cases.
- Immune system modulators, such as tacrolimus and pimecrolimus, can be used to reduce inflammation.
- Antihistamines, such as cetirizine,e can be used to reduce itching symptoms and relieve allergic responses.
- Antibiotic ointment can be given if there is a secondary infection due to bacteria. The antibiotic ointment used should not contain neomycin because it is one of the triggers of nummular dermatitis.
Like other eczema conditions, applying skin moisturizer to nummular dermatitis is very helpful in protecting damaged skin and preventing skin irritation.
Nummular Dermatitis Prevention
Just as the cause of nummular dermatitis is unknown, there is no definitive way to prevent someone from getting nummular dermatitis, but the following steps can be taken if you are at high risk or have previously had nummular dermatitis to prevent a recurrence, including:
- Use moisturizer regularly at least once a day. Use moisturizer after bathing.
- Avoid substances that cause skin irritation, such as descaling fluids, laundry detergents, or other chemicals.
- Use soap with a neutral pH, contains moisturizer, and does not contain detergent to reduce skin irritation, especially if you have very dry skin.
When to See a Doctor?
If your family or relatives have similar symptoms above, it is best to discuss with a doctor before starting self-medication so that you can be diagnosed correctly and get the right treatment.
