discoid eczema

21 Jul

Discoid eczema also known as nummular dermatitis, is the long term inflammation of the skin presented with coin shaped patches, itching, swelling and cracked skin. The condition can last from weeks to years without treatmen. It is a localised (specific area) version of atopic (caused by allergies) inflammation fo the skin.

- According to Patient UK, approx 2 per 1000 people are affected my discoid eczema
- More common in men than women
- Peak incidence in ages 50-65 years, second most likely in 15-25 years [1]
- It is uncommon in children
- More commonly found in nonwhite children [2]
- Staphlyococcus aureus infection
- Impetigo or wound infections [4]
- History or presence of dry skin
- Exposure to irritants such as cosmetics and toiletries
- History of atopic eczema
- Triggered by minor injuries such as bites or burns
- Dry environments and cold climates [5]
- Stress can aid its development
- Varicose veins (weak vein walls that are swollen and enlarged) [6]
Medical Students
- Xerosis (dry skin) is commonly associated with discoid eczema.
- Likely caused by a combination of epidermal lipid barrier dysfunction and immune response.
- Dry skin compromises the lipid barrier, allowing penetration by allergens and microbes, triggering an allergic/irritant response.
- Barrier impairment increases risk of allergic contact dermatitis (e.g., from metals, soaps, chemicals).
- Increased mast cells in lesions suggest their role in the disease.
- Neurogenic inflammation may play a part; mast cells and sensory nerves contribute to pruritus and inflammation.
- Elevated mast cell–nerve connections and neuropeptides seen compared to normal skin.
- Reduced mast cell chymase activity may lead to less inflammation suppression.
- Staphylococcus aureus colonisation is observed in patients and close contacts; its role is unclear.
Patients
- Discoid eczema is often linked to dry skin.
- Caused by a mix of problems with the skin's barrier and an overactive immune response.
- When skin is dry, bacteria and allergens can enter more easily, causing irritation or allergic reactions.
- The weakened skin barrier also makes people more likely to react to things like soaps, metals, and chemicals.
- More mast cells (immune cells involved in allergic reactions) are seen in the affected skin.
- Nerves and mast cells can work together to cause itching and inflammation.
- In people with discoid eczema, there are more connections between nerves and mast cells, and more of the body’s signal chemicals in the skin.
- Some substances from mast cells that usually reduce inflammation may be lower.
- A type of bacteria called Staphylococcus aureus is often found on the skin of people with discoid eczema and their families, but it's unclear if it worsens the condition. [3]
- Patients with a history of atopic dermatitis (AD)
- A blood relative with hay fever, AD or asthma
- History or presenting with varicose veins or stasis dermatitis
- History of contact dermatitis [7]
- Redness (erythematous)
- Scaly
- Itchiness (pruritus)
- Coin shaped and well defined borders
- Affects trunk, buttocks and extensor regions such as elbows [8]
- Skin biopsy- sample of skin is taken for investigation under microscope
- Patch test- Different potentially allergy inducing substances are placed on the skin and taped in place. The patches are typically placed on the skin, left on for 2 days and then removed to check for a reaction to certain substances.
- Skin scrapings and swabs can check for potential fungal and bacterial infections respectively [9]
- Psoriasis- Inflammatory skin condition with redness, plaques and itchiness
- Tinea corporis (ringworm)- Fungal infection that causes circular rashes
- Contact dermatitis- Inflammatory condition with dry skin causes redness and itchiness
- Lichen simplex- Plaques that are associated with discoid eczema
- Statis dermatitis- Poor lack of blood supply in the lower legs [4]
Medical Students
Lifestyle Measures
- Encourage daily lukewarm baths/showers (≤20 mins) to hydrate skin.
- Add doctor-approved bath oils to bathwater.
- Moisturise immediately (within minutes) after bathing while skin is damp.
- Recommend fragrance-free, hypoallergenic ointments or creams (preferable to lotions).
- Suggest using a humidifier at night to maintain a cool, moist environment.
- Advise use of mild, non-drying cleansers on affected areas only.
- Recommend loose-fitting, cotton clothing.
- Avoid irritants: fireplaces, heaters, and synthetic fabrics.
Medical Management
- Topical treatments (prescribed by dermatologist):
  - Corticosteroid ointments
  - Calcineurin inhibitors: tacrolimus ointment, pimecrolimus cream
  - Tar-based creams
- Apply medications on damp skin post-bathing for enhanced absorption.
- Severe or refractory cases may need:
  - Medicated dressings
  - Oral corticosteroids
  - Narrowband UVB or PUVA phototherapy
Infection Management
- Treat secondary infections with topical or oral antibiotics/antifungals as indicated.
Further Testing
- Patch testing if eczema is recurrent or resistant to treatment.
- Contact allergens are common contributors to persistent discoid eczema.
Patients
Keep Skin Hydrated
- Take a daily shower or bath (no longer than 20 minutes) using lukewarm water.
- Add bath oil if recommended by your doctor.
- Apply moisturiser immediately after bathing while skin is still damp.
- Choose fragrance-free, hypoallergenic creams or ointments (better than lotions).
- Use a humidifier in your bedroom to keep the air cool and moist.
Avoid Skin Irritants
- Use a gentle, non-drying cleanser only on areas that need cleaning.
- Wear soft, loose-fitting cotton clothes.
- Avoid fireplaces, heaters, or anything that dries out your skin.
Medication
- Treatments your doctor may prescribe include:
  - Steroid ointments
  - Non-steroid creams like tacrolimus or pimecrolimus
  - Tar-based creams
- Apply the medication right after bathing, while your skin is damp.
- If your eczema is more severe, treatment may include:
  - Special medicated dressings
  - Steroid tablets
  - Light therapy (phototherapy)
Infections
- Your doctor may prescribe creams or tablets to treat any skin infections.
Allergy Testing
- If your eczema keeps coming back, your doctor might suggest a patch test.
- This can help identify allergies that might be making your eczema worse.
- Treating these allergies can help improve your skin condition. [7]
- Bacterial infections at the site of eczema
- Permanent brown (or purple, dark brown in darker skin) discolouration [1]
- Myths
- There is only one type of eczema
- Itchy skin isn’t a red flag
- It will self resolve
- Treatment will cure/eradicate eczema
- Lifestyle changes won’t singularly help eczema
- Atopic dermatitis is contagious
- Family history will mean future generations will experience it
- Atopic dermatitis is caused by stress [10,11]
- Questions you may want to ask your doctor
  - What can I do to manage my symptoms?
  - Are there any products that can make my eczema worse?
  - Are there ways I can treat my skin to reduce my chances of another flare up?
  - What should I do if the medication doesn’t work?
  - When should I apply/use my medication?
  - How can I find out what is causing my condition?
  - How can I protect myself against allergens/ irritants?
  - What can I do to prevent complications of discoid dermatitis?
- Support
  - The British Association of Dermatologists
  - The National Eczema Society
  - Eczema Care Online Association
Bibliography
[1] https://patient.info/doctor/discoid-nummular-eczema#:~:text=rather
[2] https://emedicine.medscape.com/article/1123605-overview#a6
[3] https://emedicine.medscape.com/article/1123605-overview#a5
[4] https://dermnetnz.org/topics/discoid-eczema
[5] https://www.nhs.uk/conditions/discoid-eczema/#:~:text=The
[6] https://eczema.org/information-and-advice/types-of-eczema/discoid-eczema/#what-causes-discoid
[7] https://www.aad.org/public/diseases/eczema/types/nummular-dermatitis/causes
[8] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/dermatitis/nummular-dermatitis?query=discoid
[9] https://www.bad.org.uk/pils/discoid-eczema/
[10] https://www.everydayhealth.com/eczema/eczema-myths-debunked/
[11] https://www.dermatologynwhouston.com/5-common-myths-about-eczema/
- There is only one type of eczema
- Itchy skin isn’t a red flag
- It will self resolve
- Treatment will cure/eradicate eczema
- Lifestyle changes won’t singularly help eczema
- Atopic dermatitis is contagious
- Family history will mean future generations will experience it
- Atopic dermatitis is caused by stress [10,11]
- What can I do to manage my symptoms?
- Are there any products that can make my eczema worse?
- Are there ways I can treat my skin to reduce my chances of another flare up?
- What should I do if the medication doesn’t work?
- When should I apply/use my medication?
- How can I find out what is causing my condition?
- How can I protect myself against allergens/ irritants?
- What can I do to prevent complications of discoid dermatitis?
- The British Association of Dermatologists
- The National Eczema Society
- Eczema Care Online Association
[1] https://patient.info/doctor/discoid-nummular-eczema#:~:text=rather
[2] https://emedicine.medscape.com/article/1123605-overview#a6
[3] https://emedicine.medscape.com/article/1123605-overview#a5
[4] https://dermnetnz.org/topics/discoid-eczema
[5] https://www.nhs.uk/conditions/discoid-eczema/#:~:text=The
[6] https://eczema.org/information-and-advice/types-of-eczema/discoid-eczema/#what-causes-discoid
[7] https://www.aad.org/public/diseases/eczema/types/nummular-dermatitis/causes
[8] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/dermatitis/nummular-dermatitis?query=discoid
[9] https://www.bad.org.uk/pils/discoid-eczema/
[10] https://www.everydayhealth.com/eczema/eczema-myths-debunked/
[11] https://www.dermatologynwhouston.com/5-common-myths-about-eczema/