What is nummular eczema?

Nummular eczema, also known as nummular dermatitis or discoid eczema, is a chronic condition that causes coin-shaped spots to develop on the skin. These spots are often itchy and well-defined. They may ooze clear fluid or become dry and crusty.

Nummular eczema often appears after a skin injury, such as a burn, abrasion, or insect bite. The condition may result in one patch or multiple patches of coin-shaped lesions. The patches can last for several months.

Nummular eczema tends to occur more often in men than in women. Men usually have their first episode between ages 55 and 65. Women typically get it during adolescence or young adulthood.

Though the symptoms of nummular eczema can be bothersome, they can be treated with antihistamines and topical medicines. It isn’t contagious, which means it can’t be passed from one person to another through direct skin contact.

The most common and noticeable symptom of nummular eczema is a patch of coin-shaped lesions on the body. The lesions frequently develop on the arms or legs, but they may eventually spread to the torso and hands.

They may be brown, pink, or red. Some lesions may itch and burn. Other lesions may ooze fluid and eventually crust over. The skin around the lesions may be red, scaly, or inflamed.

Call your doctor if you believe you have nummular eczema. If it’s left untreated, a secondary skin infection could develop. Once this occurs, a yellowish crust will form on the infected lesions.

There’s no known cause for nummular eczema. However, many people with nummular eczema have a personal or family history of allergies, asthma, or atopic dermatitis.

Atopic dermatitis is a skin condition that causes itchy or scaly rashes. People with nummular eczema also tend to have sensitive skin that gets irritated easily.

The following factors may also contribute to the development of nummular eczema:

  • temperature changes
  • stress
  • dry skin
  • environmental irritants, such as soaps, metals, and formaldehyde
  • surgery

The following conditions may increase your risk of developing nummular eczema:

  • living in a cold, dry climate
  • dry skin
  • poor blood flow or swelling in the legs
  • having another type of eczema
  • a skin injury, such as an insect bite or abrasion
  • having a bacterial infection that affects the skin
  • surgery
  • some medications

Your doctor may be able to diagnose nummular eczema by asking you about your medical history and visually inspecting your skin. They may also want to perform a skin biopsy to help rule out other possible conditions, such as an infection.

During the biopsy, the doctor will remove a small piece of skin tissue from the affected area. The sample will then be analyzed for the presence of bacteria.

If your doctor suspects the lesions are a result of an allergic reaction, they may perform an allergy test as well. This may include skin tests or blood tests that can help determine what substances you’re allergic to, if any.

There isn’t a cure for nummular eczema. However, you may be able to manage your condition by making certain lifestyle changes and avoiding triggers.

To help control your nummular eczema, you should avoid:

  • wool and other irritants that may trigger your symptoms
  • excessive bathing and hot water
  • using harsh soaps
  • stressful situations
  • exposure to environmental irritants, such as household cleaners and chemicals
  • using fabric softener and dryer sheets
  • getting scrapes, cuts, and abrasions on the skin

The following can help relieve your eczema:

  • using moist bandages to cover and protect the affected areas
  • taking antihistamines to relieve itching and discomfort
  • applying medicated lotions or skin ointments, such as corticosteroids
  • getting ultraviolet light treatment for severe itching
  • hydrating skin with a non-scented moisturizer after showering

With the proper treatment, nummular eczema may improve within one year. However, nummular eczema is a chronic condition, so it may never resolve. Some lesions may go away completely while others may come and go.

Lesions on the thighs, legs, and feet often take longer to heal and may leave behind darker or lighter spots. It’s best to avoid triggers that make your symptoms worse.