What is nummular eczema?
Nummular eczema (“coin-shaped eczema”, also called discoid eczema) is a common form of eczema that stands out for its typical round eczema patches. It can occur at any age, although older people are more prone to developing it than younger people. Nummular eczema can occur anywhere on the skin, but it has a preference for the skin of the legs.
What does nummular eczema look like?
Round, red, scaly patches with a “cracked” surface, from a few millimetres to about 7 cm across. Often there is also a bacterial infection on the eczema, which can produce yellowish wound fluid that dries and can form yellow-orange crusts on the patches. As a rule nummular eczema itches considerably.
What causes it?
The precise cause of nummular eczema is not known, but the factors that can trigger this type of eczema are: a dry skin and a predisposition to atopic (constitutional) eczema. Nummular eczema has nothing to do with food allergy.
How is nummular eczema treated?
Nummular eczema can be treated well with a corticosteroid ointment, possibly supplemented with a topical antibiotic such as fusidic acid to combat bacterial overgrowth. To prevent the eczema returning again and again, it is important to keep the skin well moisturised with a maintenance cream. After healing, a lighter spot (hypopigmentation) or a darker spot (hyperpigmentation) sometimes remains visible for some time; these fade by themselves over time.
Preventing nummular eczema
The most important thing is to keep the skin well moisturised, because dryness is the main trigger for this eczema. Many kinds of moisturising ointment are available.
When to see a doctor
See your GP or a dermatologist if round, itchy, scaly patches do not improve with moisturiser, keep returning, or show signs of infection (weeping, yellow crusting, increasing redness). Assessment confirms the diagnosis and can distinguish nummular eczema from conditions it resembles, such as ringworm or psoriasis.