Discoid Eczema

What are the aims of this leaflet?

This leaflet has been written to help you understand more about discoid eczema. It tells you what it is, what can be done about it, and where you can find out more about it.

What is discoid eczema?

Eczema (also called dermatitis) is an inflammation affecting mainly the outer layer of the skin (the epidermis). There are several different types of eczema, and in some cases the cause is known whilst in others it is not.
Discoid means disc-shaped, and this name comes from the characteristic round or oval patches which occur in this type of eczema. For the same reason it is sometimes also called “nummular” eczema – nummular meaning coin-shaped.
Discoid eczema is more common in men in their sixties or seventies, although it can occur in women in their teens or twenties. It is uncommon in children; however, this is not exclusive and it can be seen in both sexes at any time in life.

What causes discoid eczema?

The cause of discoid eczema is unknown. Similar appearances can occasionally occur in other forms of eczema, including childhood atopic eczema, allergic contact eczema, and irritant eczema due to contact exposure to allergens or irritants such as soaps but these are not true discoid eczema.
Like other forms of eczema, discoid eczema can be worsened by scratching, local infection, and dryness of the skin.

Is discoid eczema hereditary?

No.

What are the features of discoid eczema?

This is a highly inflamed type of eczema, and it is usually extremely itchy.
It is usually worst on the limbs, but the body is often affected too. It does not involve the face or the scalp.
Each patch begins as a small group of red spots and tiny bumps or blisters, which enlarge rapidly into a red swollen moist round patch. This appearance may resemble an infection; however, while discoid eczema may become infected, that is not how it begins. After a while the patches become dry and scaly. A dozen or so patches may occur on each limb and on the body. Most are less than 10 cm (4 inches) across. Some patches may clear in the middle.
If untreated, discoid eczema may persist for months or years, often worsening and improving, and sometimes coming back at the same sites each time.

How will it be diagnosed?

Discoid eczema is usually diagnosed by its typical appearance. Investigations may be needed to rule out other conditions; for example, taking a skin biopsy (small sample of the skin cut under local anaesthesia) from one of the patches, allergy contact patch tests to look for allergic contact eczema, or the examination of skin scales for a fungal infection. Swabs may be taken to check for a bacterial infection.

Can discoid eczema be cured?

No, treatment controls the condition but does not cure it. Whilst discoid eczema has been known to go away by itself spontaneously, there is no guarantee that it will not reoccur.

How can it be treated?

Mild steroids are inadequate for discoid eczema. The mainstay of treatment is a potent steroid cream or ointment. This should be applied once or twice daily (depending on which topical steroid has been prescribed) to all affected areas, avoiding the normal skin, until the inflammation is completely suppressed. Treatment should restart at the first sign of recurrence.
Other non-steroid creams such as tacrolimus ointment or pimecrolimus cream can be helpful.
If infection occurs an antibiotic will be necessary, either included in the steroid application or as tablets.
The surface of chronic patches is dry and scaly, and an emollient (moisturising) cream or ointment is essential. This should also be applied to the unaffected skin, especially if it is dry. The emollient should be continued indefinitely, even after the patches have cleared up and the steroid cream has been discontinued.
In more severe cases, courses of steroid tablets may rarely be required. Occasionally, ultraviolet light treatment may be considered by your doctor.

Where can I get more information about discoid eczema?

Web links to detailed leaflets:
http://www.emedicine.com/derm/topic298.htm
http://dermnetnz.org/dermatitis/nummular-dermatitis.html
http://www.nhs.uk/conditions/Eczema-(discoid)/Pages/Introduction.aspx