Nummular eczema

Nummular eczema is a chronic, inflammatory skin condition associated with itchy round spots. The reddish-brown rashes are particularly common on legs and arms, and may be coin-shaped.

The eczema often occurs in men over the age of 50. It is less common in women and then tends to occur in teenagers or young adults. Children also sometimes get nummular eczema.

The skin condition usually occurs in episodes across months or years. The eczema is treated with anti-inflammatory cortisone creams, for example.

Characteristic of nummular eczema are round, reddish-brown spots on the skin. They are shaped like coins. The spots may be between one and 10 centimeters in diameter.

The spots can itch and burn, first weeping and then crusting. If yellowish crusts form, it indicates an additional infection with bacteria.

Some people with nummular eczema suffer from single rashes, while others have very many. They usually occur on the legs, arms, hands, or feet. If they occur on the torso, they are usually on the lower stomach, lower back, or bottom.

The rashes can last for several weeks or even months. Over time they dry out and become flaky. Sometimes the spots get pale in the center and become ring-shaped.

Nummular eczema usually occurs in episodes. In an acute episode, the skin rashes often recur in the same or neighboring places.

As yet little is known about exactly what causes nummular eczema. But it is thought that there are many contributing factors and potential triggers. These include:

• neurodermatitis
• contact allergies, for example to metals such as nickel
• very dry skin
• poor circulation and swellings in the legs
• skin damage, for example insect bites
• skin infections from bacteria
• certain medications

The eczema is usually identified through the typical coin-shaped rashes. Specific laboratory tests are not normally required.

If doctors suspect an additional infection, they sometimes take a skin swab. An allergy test is sometimes carried out, too, to identify the eczema’s possible triggers.

Nummular eczema is often treated with cortisone creams that have an anti-inflammatory effect. If the skin areas affected are also infected with bacteria, doctors additionally prescribe an antibiotic aimed at the bacteria.

Antihistamines are also sometimes used, in particular to alleviate itching during the night and to prevent sleep disorders. Antihistamines act against allergic reactions. 

In general it is important to protect the skin and to care for it well. The following are recommended, for example:

• using mild soaps
• only brief, lukewarm showers
• putting cream on the skin after a shower while it is still a little damp
• avoiding known irritants and substances that trigger allergies (allergens)