Nummular eczema, also called nummular dermatitis, is a long-lasting skin condition that causes round, coin-shaped patches of irritated skin. The word “nummular” comes from the Latin word for “coin,” which describes the shape of the patches. As the condition develops, these patches may become scaly and can look like other skin problems, such as ringworm or psoriasis. While nummular eczema can be uncomfortable and affect your quality of life due to itching and its appearance, it is not life-threatening. However, it can come and go, so ongoing treatment is important to manage flare-ups and keep symptoms under control.

Clinical Presentation

The main feature of nummular eczema is the appearance of well-defined, coin-shaped patches that can range in size from small spots to larger plaques. These patches usually start as red, itchy areas and may later become dry, scaly, or crusty. Over time, the center of these patches may clear up, leaving a ring-like appearance around the edges. Nummular eczema most commonly appears on the arms and legs, and its symptoms can worsen in cold weather or low humidity.

It’s important to differentiate nummular eczema from other skin conditions that may look similar, such as fungal infections, psoriasis, and atopic dermatitis. To make an accurate diagnosis, a thorough clinical evaluation, including a review of medical history and a physical exam, is necessary.

Etiology and Risk Factors

The exact cause of nummular eczema is not fully understood, but several factors are believed to play a role in its development. It is more common in the winter, when dry skin is worsened by cold air, low humidity, and indoor heating. Dry skin (xerosis) is a major contributing factor, as it weakens the skin’s natural barrier, making it more vulnerable to irritants and allergens. Environmental triggers such as harsh soaps, wool, frequent bathing, and fabric softeners can also irritate the skin and worsen symptoms. Unlike atopic eczema, which is linked to allergic reactions, nummular eczema is mainly an irritant contact dermatitis, meaning it is caused more by irritation than by an allergic response. However, allergies may still make the condition worse.

Diagnosis

Nummular eczema is usually diagnosed based on its characteristic coin-shaped patches and symptoms like itching. However, it’s important to rule out other skin conditions that may look similar, such as fungal infections (like tinea corporis), psoriasis, and contact dermatitis. In some cases, a skin biopsy may be needed to confirm the diagnosis and exclude other possible causes, especially if the symptoms are unusual or if there’s any doubt about the nature of the lesions.

Management and Treatment

While there is no cure for nummular eczema, various treatments can help manage flare-ups and reduce the likelihood of recurrence. Treatment typically involves a combination of topical therapies, skin care routines, and lifestyle changes.

• Topical Corticosteroids:

• • • High-potency corticosteroids are the first-line treatment for controlling inflammation and relieving itching. These should be used under a healthcare provider’s guidance, especially for long-term use, to avoid potential side effects like thinning of the skin.

• Adjunctive Therapies:

• • • If the eczema becomes scaly, coal tar may be added to your treatment plan. It helps reduce inflammation and scaling, though it has an unpleasant odor and can stain clothing.

    •  Medications like tacrolimus or pimecrolimus may be recommended for patients who can’t tolerate steroids or as maintenance therapy to prevent flare-ups.

• Oral Medications:

• • For more severe cases, short-term use of oral corticosteroids or immunosuppressive drugs like methotrexate or azathioprine may be considered to control flare-ups.

  • If a secondary bacterial infection (such as Staphylococcus aureus) occurs, oral antibiotics like cephalexin may be prescribed for a short course (1-2 weeks).

• Phototherapy:

  • Narrowband UVB light therapy can be effective for chronic cases of nummular eczema by helping to reduce itching and inflammation. This treatment should be done under medical supervision in a dermatology clinic to avoid skin damage.

Skin Care and Preventive Measures

Good skin care is vital to managing nummular eczema and preventing future flare-ups. Here are some helpful tips:

• Moisturization: Apply emollients like Neutrogena Body Oil or Vaseline immediately after showering while the skin is still damp to lock in moisture and improve the skin’s barrier function.

• Bathing Practices: Limit showers or baths to once a day, and use lukewarm water instead of hot, as hot water can worsen dryness. Use mild, fragrance-free soaps like Cetaphil or Dove to avoid skin irritation.

• Clothing: Wear soft, cotton clothing and avoid wool or rough fabrics that may irritate the skin. Also, avoid fabric softeners and scented detergents.

• Avoiding Triggers: Identifying and avoiding environmental triggers such as harsh soaps, frequent bathing, and dry air can help reduce flare-up frequency and severity.

Conclusion

Nummular eczematous dermatitis is a long-lasting condition that often comes and goes, causing well-defined, coin-shaped patches on the skin. While the exact cause is not fully understood, environmental factors and genetic predisposition can worsen the condition. Although there is no permanent cure, treatment options such as topical corticosteroids, oral medications, UV therapy, and proper skin care can help control symptoms and improve quality of life. Effective management includes avoiding triggers and following a regular skincare routine to prevent flare-ups.

References

1. Cherney, J. R., & Kroumpouzos, G. (2023). Nummular eczema: A review of clinical presentation, pathophysiology, and management. Journal of the American Academy of Dermatology, 88(2), 319-325. https://doi.org/10.1016/j.jaad.2022.08.074

2. Guttman-Yassky, E., Silverberg, J. I., & Paller, A. S. (2021). Nummular dermatitis: A comprehensive review of diagnosis and management. Dermatitis, 32(3), 240-248. https://doi.org/10.1097/DER.0000000000000805

3. Sukenik, J. D., & Korman, N. J. (2022). Eczema management: Therapeutic strategies for chronic nummular dermatitis. American Journal of Clinical Dermatology, 23(4), 487-494. https://doi.org/10.1007/s40257-022-00647-3