What Is Discoid Eczema (Nummular Dermatitis)? What Causes Discoid Eczema?

Discoid eczema, also known as discoid dermatitis, gravitational eczema, nummular dermatitis, and nummular eczema is a form of dermatitis. It is a chronic (long-term) or recurrent condition. A rash appears on the skin in the form of red coin shaped discs - plaques of eczema - which can affect different parts of the body, but primarily the lower legs, hands and forearms, and sometimes the trunk. It is extremely itchy and uncomfortable. Dermatitis means "inflammation of the skin".

The round or oval plaques, made of tiny raised red spots and scaling on a red base, have well defined edges. Affected areas of skin can range in size from just a few millimeters to a few centimeters.

Discoid eczema is not contagious - you cannot catch it by touching an affected person, or being near him/her. Experts say there is no link between food allergies and the condition. It is solely a dermatological (skin) condition; no other systems are affected. Although infection is common, it is secondary and not causative. People with discoid eczema are at risk of developing other forms of dermatitis.

It is also known as nummular eczema because of the Latin word nummus, meaning "coin".

Symptoms of discoid eczema are more frequently reported to doctors during the winter months, when indoor humidity levels are lower. Although discoid eczema symptoms can occur at any age, they are more commonly seen in males in their 60s and 70s. There is also a lesser peak during the teen years to mid 20s. Discoid eczema is extremely rare in children.

According to the National Health Service (NHS), UK, approximately 2 in every 1,000 people are affected.

According to Medilexicon's medical dictionary, Nummular eczema is "discrete, coin-shaped patches of eczema".

What are the signs and symptoms of discord eczema?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

• The affected areas are red and have well-defined edges.
• On top of the coin-shaped plaques there may be small blisters, scales or yellowish crusts - often a sign of a staphylococcal (bacterial) infection.
• Typically, the affected areas are symmetrical, especially on the limbs.
• The lesions (affected areas) are extremely itchy, often resulting in lichenification (see next line).
• Lichenification - constant scratching and rubbing leads to thick, leathery skin. Prolonged scratching and rubbing causes the epidermis (outer layer of skin) to become overgrown (hypertrophied). The skin thickens and there are exaggerated skin markings; giving the skin an appearance like leathery bark.
• Apart from itching, affected areas may also burn or sting.
• Itching tends to be worse at night.
• Symptoms most commonly appear on the legs, but may also do so on the arms, trunk, hands or feet. The face and scalp are not affected.

Put simply - discoid eczema generally starts off as round/oval plaques of very small red spots and blisters. They are red, oozy and crusty. The plaques eventually dry and become scalier, sometimes with a clear middle.

Signs and symptoms may be confused for ringworm infection (a type of fungal infection) or contact eczema.

What are the causes of discoid eczema?

We do not know what causes discoid eczema. We know that it can be triggered by:

• An insect bite
• A burn
• Some other minor skin injury
• Administration of interferon or ribavirin for hepatitis C treatment

We also know that:

• Discoid eczema is not usually linked to an allergy
• People with discoid eczema often also have atopic eczema
• The condition does not appear to have a genetic link (does usually not run in families)
• Most individuals with discoid eczema have dry, sensitive skin
• Venous insufficiency and stasis (stoppage or slowdown in blood flow) may aggravate symptoms on the lower legs.

Diagnosing discoid eczema

A GP (general practitioner, primary care physician) may be able to make a diagnosis after seeing the hallmark signs and symptoms. In some cases the patient may be referred to a dermatologist (specialist skin doctor).

• Samples - the doctor may take scrapings of lesions for analysis and to rule out tinea (ringworm). Ringworm is a fungal skin infection which has similar signs to discoid eczema. The fungi that cause ringworm are called dermatophytes.
  
• Secondary infection - if there is evidence of any secondary infection the doctor will take a swab for analysis.

A biopsy is not generally needed.

What are the treatment options for discoid eczema?

Although there is no straightforward cure for discoid eczema, there are treatments which may help prevent recurrences, as well as symptoms. Treatment focuses on:

• Rehydrating the skin
• Identifying and treating infections
• Alleviating inflammation

The following measures are known to help patients with discoid eczema:

• Bathe/shower once or twice a day. The water should be cool. In order to seal the water in the skin medicated topical preparations or moisturizers should be used.
  
• Apply medication to damp skin. This helps seal it, so that the medication can penetrate.
  
• Topical steroids - in medicine topical means "applied on to the skin". Corticosteroids rapidly reduce inflammation. If the patient's skin is very red and inflamed the doctor may prescribe a topical corticosteroid. In patients with severe symptoms oral steroids may be required.
  
  Applying a corticosteroid - apply to the affected area sparingly. Follow the instructions on the leaflet carefully. You can also ask the doctor, and if you cannot remember, ask a qualified pharmacist.
  
  Applying a corticosteroid during a flare-up - the corticosteroid should not be applied more than twice daily. Most patients will only require one application per day. After the flare-up has cleared up you should continue for another 48 hours.
  
  If the patient is using corticosteroids on a long-term basis, he/she should check carefully with the doctor on how and when to apply it.
  
  Discoid eczema is harder to treat than atopic eczema and may require higher dosages and longer treatment courses with steroids (than atopic eczema).
  
  Remember that steroid creams can mask or further spread an infection.
  
  If you have tried corticosteroids and symptoms have not improved you should see your doctor.
  
• Secondary infections - if there is a secondary infection the patient may be given an antibiotic; usually one against streptococci. Good hand hygiene can help prevent eczema from becoming infected - keep hands clean and nails clean and short. Try to avoid scratching.
  
• Antihistamines - they may help sleep more than the itching. Hence, the older sedating ones tend to be better if the aim is to get a good night's sleep. They should be taken about one hour before going to bed. Sometimes drowsiness is still present the following day. If the patient feels drowsy the following morning he/she should not drive or operate heavy machinery.
  
• Tar preparations - these may help reduce inflammation if there are older, thickened, scaly plaques.
  
• Environments - the patient will find that cool and moist environments help reduce symptoms, while the opposite - hot and dry ones - make them worse. If possible, seek out cool and moist environments.
  
• Phototherapy - involves the use of natural or artificial light. In its most simple form, all the patient has to do is expose himself/herself to controlled amounts of natural sunlight.
  
  Other forms of phototherapy include using artificial ultraviolet A (UVA) or ultraviolet B (UVD) light, either on its own or in combination with drugs.
  
  Light therapy is very effective. It is important that it is done with a qualified health care professional. Exposure to sunlight has many beneficial effects, but it does, however, also have risks if not controlled properly. Examples of risks include premature skin aging and a higher risk of developing skin cancer. There is also a risk that the heat worsens the itching.
  
• Emollients - agents that soften and smooth the skin - it can be a cream, bath oil, soap substitute, lotion or ointment. They keep the skin supple and moist. Emollients are an important part of eczema treatment. The skin of people with eczema is usually dry; emollients help keep them moisturized, which helps prevent cracking and irritation.
  
  Finding the right emollient may be a question of trial-and-error at first. The patient may have to try several different ones before hitting on a suitable one. Patients usually end up needing different types of emollients for different parts of their body.
  
  Some emollients are specific for very dry skin, while others are aimed at less dry skin. Ointments are generally prescribed for drier skin, while creams and lotions are usually prescribed for other skin types.
  
  It is not uncommon for patients to find that an emollient is no longer as effective as it used to be. Others may start experiencing skin irritation after long-term use. If either case happens you should see your GP.
  
  Individuals who use an emollient in the bath should remember that they make things slippery - care should be taken when getting in and out.
  
• OTC (over the counter) medications - these are medications which can be purchased without a doctor's prescription. For discoid eczema they may include shampoos, emollient products and some low-dose topical steroids. A good source of advice on different products and their usage is a pharmacist.
  
  Peanuts - if the patient has a peanut allergy it is important to let the pharmacist know, because some products contain peanuts. The doctor should also know about any peanut allergy.
  
  Patients should see their doctor if OTC preparations have not improved symptoms after a week.
  
• Wet wraps - the use of dampened bandages to reduce inflamed eczema is an old remedy. Sometimes diluted steroids and/or emollients are added to the preparation that dampens the bandages.
  
• Complementary treatments - very popular among patients with atopic eczema, and used by some with discoid eczema. They include aromatherapy, massage, homeopathy, and some herbal remedies, to mention but a few. It is important to remember that although patients do report benefits, a lot of information one reads in books and on the internet is anecdotal. For therapy to be convincing, it should undergo proper clinical tests, usually carried out and compared to a placebo (dummy treatment).
  
  Before undergoing any complementary/alternative therapy, check it out carefully and make sure you get it from a reputable source.
  
  Patients should inform their doctor about all complementary treatments they are taking. Asking a qualified pharmacist about complementary therapies is useful.
  
  A study, carried out by Scientists at the Chinese University of Hong Kong found that a traditional Chinese herbal concoction, consisting of Flos lonicerae (Japanese honeysuckle), Herba menthae (peppermint), Cortex moutan (root bark of peony tree), Atractylodes Rhizome (underground stem of the atractylodes herb) and Cortex phellodendri (Amur cork-tree bark) may help people with eczema and reduced their needs for medications.

What are the possible complications of discoid eczema?

• Secondary infections
• Infections may cause permanent scars
• Excoriation (scratching and picking the skin) may cause scars
• If lesions are slow to heal there may be permanent brown blemishes (macules) on the skin, especially on the legs.

Reducing recurrences

• Keep the skin well hydrated with liberal use of moisturizers. Add oils to the bath.
• Do not have hot baths or showers.
• Do not use soaps.
• Wear clothing that does not irritate the skin. This usually means choosing natural, rather than man-made fabrics.
• Loose clothing is better than tight clothing.
• If your home has air-conditioning or central heating you may find an air-humidifier helps ease symptoms and reduce the number of recurrences.
• Try to avoid scratching.
• After a bath/shower - when you dry yourself, gently pat the skin dry with a soft towel (do not rub).
• Adherence - follow your doctor's instructions and recommendations carefully.