Questions And Answers About Selected Skin Conditions

Eczema

What is eczema?
Eczema (also called dermatitis) is an immunological, inflammatory reaction in the skin that can affect people of all ages and is caused by irritants, allergens or by internal physiological mechanisms. It is not an infectious condition and cannot be caught by touching someone else. There are many forms of eczema and the pattern and severity vary from person to person. In acute forms, severe blistering may occur – the word eczema means ‘to boil over’ in Greek. In chronic eczema, the skin will often be reddened and scaly and may also have small blisters. The lesions can be intensely itchy, leading to skin damage through scratching and the risk of secondary infection.

How common is eczema?
It is difficult to obtain accurate statistics on many skin conditions, but eczema is easily the commonest cause of consultation with GPs for disorders of the skin – accounting for some 30 per cent of the total, compared to nine per cent for acne and six per cent for psoriasis. The lower percentage for acne and psoriasis reflect the smaller age range who are affected by acne and the fact that many psoriasis sufferers are referred on to specialist dermatologists.

What are the different types of eczema?
The different forms of eczema are not easy to classify, but can be broadly divided into exogenous and endogenous forms, each with several varieties. Exogenous means ‘external’ and the cause may be identifiable as a factor outside the body – for example, a chemical, an ingredient in a soap, or sunlight, while endogenous implies an internal event, perhaps an imbalance in the body’s biochemistry – though often the precise trigger cannot be identified. Another alternative is to divide eczema into acute and chronic types. In many cases, this can be done by examination of the nature and form of the lesions. In acute eczema, there is often fluid accumulation within the dermis, leading to separation of the layers and blistering. The skin in chronic eczema is often thickened rather than blistered. This is due to deeper prickle cell and horny layers, and to elongation of the dermal ‘fingers’ into the epidermis. In both acute and chronic eczema, inflammatory cells are attracted into the area, which further exacerbate the condition.

How do these forms of eczema differ from each other?
Many of these variants of eczema differ in their appearance, the site(s) of the body affected, the age at which they develop, their prognosis (i.e. how they progress over time) and the way in which they are treated. The various forms cannot be described in detail in this booklet, but aspects of the commoner ones are summarised below. For a fuller discussion, (especially of how to treat and live with them) please consult the leaflets produced by The National Eczema Society, whose address can be found on the back cover.

• Contact dermatitis: In this condition, which can occur at any age, there is a skin reaction in which the causative agent is external – commonly in the home or workplace. It is frequently an irritant chemical (e.g. an abrasive, an acid or alkali, a metal such as nickel or chromium, a solvent, or a detergent) but may also be a substance to which the person is allergic. In this last case, the condition is a type of immune reaction called a hypersensitivity type IV reaction which has the potential to appear on other parts of the body. In either case, sensitivity can build up rapidly or may take years of repeated contact.

Commonly affected areas are the hands and face, or skin that has been in contact with metal (e.g. watch straps, clips on underclothes, earrings etc.). The clinical picture is often one of reddened, painful, itchy and blistered patches which then crust over. Repeated episodes can lead to skin thickening, scaling and cracking.

In cases of contact dermatitis, avoidance of the source of irritation is very important. Patch testing may help identify the culprit. If avoidance is not entirely possible, then protective clothing or other barrier methods need to be adopted.

• Atopic eczema: This is a chronic and often intensely itchy condition with no obvious cause, associated with skin inflammation. Of those individuals who develop it, about 60 per cent do so before the age of one year. Between 12 and 15 per cent of babies are affected and there is often a family history of atopic allergy (asthma, nasal allergy (hay fever) or eczema). Fortunately, three out of four people grow out of the condition by the age of 15 and only a small number relapse.

The first infantile rash is usually on the face and hands, but by age two, common sites are the wrists and ankles and the areas behind the knees and in front of the elbow. The skin can be dry, cracked and crusted. Loss of sleep may be a problem due to itching. Bleeding is frequent, due to scratching and secondary infection may then follow.

Adults who had atopic eczema as a child are the most likely to develop the condition later – usually as a hand dermatitis aggravated by irritants. However, in a few adults the condition is chronic, severe, generalised and accompanied by skin thickening.

• Seborrhoeic eczema: One form of this condition is infantile seborrhoea. It is common under the age of one year, often starts in the nappy area or head and can rapidly spread, causing great concern to parents. Fortunately, it looks worse than it is: it is not itchy or sore and the baby is not unwell. It normally clears up quickly but if secondary infection is suspected, a doctor should be consulted.

Adult seborrhoeic eczema tends to affect the areas where there are most sebaceous glands (face, scalp and chest) but sebum secretion appears to be normal. There appear to be genetic and endogenous factors involved which permit an excessive growth of a yeast known as Pityrosporum ovale. The condition is often mild and manageable by using medicated shampoos or preparations available on prescription that contain anti-fungal medicines. It is most troublesome when infected by other yeasts such as Candida or by bacteria. It has a tendency to recur.

• Gravitational eczema: This form arises on the lower legs and affects mainly middle-aged and elderly people. It is due to underlying disease of the deep vein valves, which causes increase pressure, leakage of fluid into the skin, pigmentation, and blistering. Over time the skin thins and becomes fragile with an increased risk of ulceration. Treatment usually involves moisturising creams with or without a mild steroid.

• Discoid eczema: The cause of this form is not known, but it usually affects adults with very dry skin. It typically appears as either circular, coin-sized rings of very itchy, red lesions on the limbs or as small pustules – sometimes on the hands. Over a period of days the lesions weep, become crusted and may get infected. Later, they become scaly and dry up, leaving a flaky patch of skin.

• Pompholyx eczema: This form is restricted to the hands and feet and is characterised by blistering. The blisters often weep, break, and itch. The cause is not known, but metal sensitivity and allergies may be involved in some people. The condition may recur and become chronic with thickened, cracked skin.

• Asteatotic eczema: This mainly affects elderly people, mostly on the lower legs, but occasionally on the upper arms, thighs and lower back. Though the cause is not known, it seems to be connected with a loss of skin oils, a dry atmosphere, hot baths, and vigorous towel drying. The skin at first appears dry and a little rough, but then develops a distinctive banded pattern often with cracking. It involves mostly the surface layers of the skin, but can be very itchy and sore.

What causes eczema?
The skin is an important barrier between our inner organs and the outside world. This is a reflection of the toughness and flexibility of the skin, but also because it is impregnated with water and oils. These protective qualities can be compromised by chemicals such as excessive water, detergents, chemicals or solvents which wash out the protective oils, or by an excess or deficiency of internal factors such as hormones, vitamins or growth factors. In either case, irritants or allergens can then penetrate (as in contact dermatitis) or an excessive inflammatory or immune reaction may arise in the deeper layers. In either case, the cardinal signs of inflammation occur: erythema (redness), oedema (fluid build-up in tissue or as blisters), pain (often as an itch), and heat (burning sensation). This then leads to a breakdown in the layers of the skin, with flaking and weeping.

Does eczema tend to run in families?
Some forms of eczema, such as contact dermatitis and those affecting the elderly, seem to relate mainly to factors in the environment or to the ageing process rather than to inheritance. However, the development of atopic eczema does appear to be inherited and up to a quarter of the population will develop one or more of the atopic conditions (eczema, asthma, or allergic reactions). However, the picture is quite complicated and most experts believe that many genes plus environmental factors are necessary for atopy to develop. Sometimes the conditions will be sequential. For example a child may have eczema and when this clears up, begin to be asthmatic.

Will I always have eczema?
Many cases of eczema are acute in nature. Most of these will respond to treatment and never recur. However, it has to be realised that an episode of eczema may imply that you have a particular sensitivity and be prone to recurrences. Careful assessment of your lifestyle is therefore necessary to avoid exposure to irritants or allergens, or to avoid foods thought to be triggers. Keeping the skin clean, supple and healthy will also help reduce the risk of recurrence.

Other forms, such as the atopic eczema of childhood, affect a particular age range. In the majority of cases these will also clear up, though other atopic conditions may continue to be troublesome.

Unfortunately, many people do have repeated episodes of eczema or experience a semi-chronic or chronic condition. These will often require a personalised management plan, sympathy from friends and family, and may require both physical and psychological support.

What are the current medicines for eczema?
At the moment, treatment is similar for most types of eczema. These are listed below.

• Emollients – creams, ointments, lotions or gels which help keep the skin moist and supple and reduce inflammation.
• Tar bandages – impregnated bandages that can be used overnight.
• Wet wrap bandages – these are warm, wet, tubular bandages put onto the body over a moisturiser or a mild/moderate steroid, followed by an overlayer of dry bandages. They should be used only after a GP’s or dermatologist’s assessment but are especially useful for children. A booklet on this form of treatment is available from the National Eczema Society.
• Topical corticosteroids – When applied to the skin, these can be helpful for controlling a flare-up and in promoting healing. For severe eczema, an oral steroid (taken by mouth) may be required.
• Antibiotics, antifungals and antivirals – Used as appropriate to control infections. Antibiotics may sometime be combined with steroids (e.g. for seborrhoeic eczema) or used orally if generalised infection is suspected.
• Antihistamines – help manage very itchy eczema.
• Topical immunomodulators – a group of more recently introduced medicines that offer an alternative to steroids for facial and hand eczema.
• Other medicines and combinations – for people with severe disease, several more powerful medicines may be used, including agents that damp down the immune system, such as cyclosporin and azathioprine. These may be used in conjunction with ultraviolet light sessions.

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Frequency (percentage) of skin diseases seen by GPs in the UK. Infections include bacterial, fungal and viral - click for larger image