Eczema (aka Dermatitis)

Eczema (aka Dermatitis) presents as a poorly demarcated, itchy rash. There are several causes. By far the most common is atopic eczema, but irritants and venous stasis can also cause the condition.

Atopic Eczema

This results from an IgE-mediated, T-cell auto-immune response.

Epidemiology and Aetiology

• Affects approximately 5% of children in developed countries. Incidence is highest in developed countries in urbanised areas.
• History of atopy (70% of cases)
• Family history – genetic component
• Breast feeding – breast feeding a child as the sole nutrition in the first 3 months of life decreases risk in those with a FH

Pathology

• The Hygeine hypothesis is commonly used to explain the increasing incidence of eczema and other atopic disorders. It is believed that in developed countries, increased cleanliness around the home, early childhood vaccination, and small family groups reduced the exposure of young children to pathogens. This results in the over-production/expression of pro-allergic T-cells, increasing the likelyhood of the child becoming atopic.
• In a genetically susceptible individual, there is an IgE-mediated T-cell immune response, after exposure to allergens.
• Follows a chronic / relapsing-remitting course

Clinical features

• Rash, typically on the flexor surfaces (inside of the elbows, wrists and knees), around the eyes, and on the neck. Can also involve the scalp and abdomen.
  • Infants – typically, scalp, face and flexor surfaces
  • Adults – typically chest, neck and flexural
• Pruritus! – this is the main feature, and is worse with dry air, sweating, local irritation, stress, and sometimes wool clothing.
• Onset is usually within the first 3 months of life, but it can occur later

Diagnosis

Diagnosis is clinical.

It can be difficult to distinguish contact dermatitis from atopic dermatitis, so a good history, including work life, washing products (for skin and clothes) and any other social factors is important.

Psoriasis may also present similarly, but is usually on the extensor surfaces (outside of the elbows, knees etc). Psoriasis also has a more ‘shiny’ appearance, and there may be fingernail signs.

Prognosis

• Usually improves throughout childhood, and many patients are asymptomatic by age 5.
• Even if there is apparent regression, symptomatic flare-ups still tend to occur throughout childhood and adolescence

Complications
Lichenification –this is where the skin becomes thickened and leathery, as a result of epidermal hypertrophy, usually as a consequence of excessive scratching and rubbing.
Staphylococcal infection of lesionsEczema herpeticum

• Widespread herpes infection of eczema lesions
• Typically occurs in children
• Presents with vesicular lesions, typically around the site of a recent dermatitis flare up, although can occur anywhere on the body.
• Patient may become particularly ill, with fever and lymphadenopathy, usually about 5 days after the vesicles appear
• The lesions may later become infected with staphylococci
• Very rarely, there may be a viraemia, which can be fatal

Cataracts – are a risk in those with long-term disease. Can be a feature of the disease itself, but also result from the use of steroid agents around the eyes, so don’t prescribe steroids for eczema around the eyes!
Eythrodermic eczema – eczema involving >90% of the body!

 ManagementRemoval of identified precipitating factors

• These can be difficult to identify
• Dust mite faeces is thought to be a common cause, but is very difficult to control. Some may benefit from measures to control this, such as limiting exposure to carpets, high-filtration vacuuming of mattresses, and use of a Gore-Tex mattress cover
• Avoidance of dietary factors is not thought to be beneficial

The aim of treatment is to keep the skin as moist as possible, and thus the mainstay of treatment is the use of moisturising agents –emollients. These come in a variety of forms:

• Creams –these are water based, and least potent
• Lotions – these have both water and oil components and are moderately potent
• Ointments – these are oil based and are the most potent
• For example, you might start a patient on e45 cream, and step this up to oil based creams, such as Vaseline (and other petroleum based products – tar is the most potent!), if this is ineffective. Typically, the more potent the emollient, the more greasythe product is (and thus the more unpleasant it is to have it sitting on your skin!)
• Emollients should be used liberally and regularly! – this may mean >500ml/week
• Special bath/shower emollient products are also available
• Avoidance of soaps if possible. Soaps are very drying to the skin. Wash hands and bathe as little as possible, and use luke-warm water.
  • Some advise the use of emollient as a soap – e.g. patients may be encouraged to apply the emollient as an alternative to washing their hands with soap and water.

Use of steroids – steroid creams are widely used to bring an exacerbation under control. Note that steroids should be applied before emollients! – otherwise, no steroid gets to the surface of the skin!

• Mild corticosteroids – e.g. 1% hydrocortisone, or 0.05% clobetasone (Eumovate – this is more potent than 1% hydrocortisone)
  • On the face – use for <5 days – AVOID AROUND THE EYES – (causes cataracts).
  • On the rest of the body – use for <2 weeks
• Potent corticosteroids – e.g. 0.1% betamethosone, or clobetasone (Dermovate – highly potent!)
  • NOT FOR USE OF THE FACE
  • On the rest of the body – useful for persistent rash, and in those with lichenification.
• Other preparations – Haelan tape – fludroxycortide – is useful for the fingers, and healing of fissures
• Typical side effects of topical steroids:
  • Side effects are rare with topical agents, so don’t be afraid to use them!
  • Skin thinning
  • Striae formation
  • Telangectasia
  • Adrenal suppression – cushing’s syndrome – rare!

Treatment of staphylococcal infection

• Usually with the use of oral Fluticasone
• Topical fusidic acid has fallen out of favour as it is of little proven benefit

Immune modulating agents      

• Pimecrolimus and tacrolimus – are immune modulators (T-cell suppressants) that are licensed for use in moderate to severe eczema. They are usually used as alternatives to topical steroids, and are available as topic or oral preparations.
• Can cause local stinging / flushing of the skin, but this tends to subside after several days use

Phototherapy

• May be useful for many patients
• Sunlight is beneficial
• UVA/UVB therapy is effective in treating disease resistant to topical agents. It can cause sun damage, and thus is avoided in children

Systemic therapy

• Very rarely, systemic therapy, such as systemic steroids may be used

Asteatotic eczema

• “Crazy paving” eczema -
• Fissures and cracks on dry skin. Particularly scaly.
• Usually occurs on the shins, typically in elderly patients, but may also be on the trunk.
• Thought to be the result of dehydration of the epidermis
• More common in winter
• Just moisturise and it should go away!

Lip lickers dermatitis

• Soreness around the mouth due to excess lip licking
• Just use moisturiser – moisturises the area, and discourages the habit of lip-licking as it tastes bad

Reference : http://almostadoctor.co.uk/content/systems/dermatology/eczema-dermatitis

http://www.webmd.com/skin-problems-and-treatments/guide/skin-problems-treatments-symptoms-types