Discoid eczema, also known as nummular dermatitis, is a common type of dermatitis. It can occur at any age and affects males and females equally.
The cause of discoid eczema is unknown. There are dry and wet types.
In most cases, discoid eczema does not run in families. It does not result from food allergy. It is not infectious to other people, although it sometimes becomes secondarily infected by bacteria.
- Minor skin injury such as an insect bite or a burn may start it off.
- In some children, it is a manifestation of atopic dermatitis.
- Autoeczematisation or id reactions can present as discoid eczema.
- It may be termed ‘varicose eczema' when it runs along the leg veins or may complicate gravitational eczema.
- Dry skin in the winter months can cause dry non-itchy round patches.
- The wet type presents as crusted or blistered patches.
- Discoid eczema has been observed to be more prevalent in association with alcohol abuse.
Discoid eczema can affect any part of the body particularly the lower leg. One or many patches appear, and may persist for weeks or months.
The majority of patches are round or oval, hence the name ‘discoid‘ or ‘nummular' dermatitis, which refers to their disc or coin shape. They can be several centimetres across, or as small as two millimetres.
The patches are pink, red, or brown and well defined. They have a dry cracked surface or a bumpy, blistered or crusted surface. Discoid eczema may be extremely itchy, or scarcely noticeable. The skin between the patches is usually normal, but may be dry and irritable.
Severe discoid eczema may generalise, with numerous small to large itchy lesions appearing all over the body due to autoeczematisation reaction.
The patches may clear up without leaving a sign. However, in darker skins, marks may persist for months. These may be dark brown (postinflammatory hyperpigmentation) or paler than surrounding skin (postinflammatory hypopigmentation).
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