The term ‘eczema’ is used for a group of conditions that show a similar pattern of changes in the skin, giving rise to specific changes on the surface. The word itself comes from the Greek and means ‘to boil or flow out’ – anyone who has had acute eczema will understand how appropriate this is.

In acute (short-term) eczema, intense inflammation leads to the formation of little blisters (vesicles) in the skin, which soon burst or are scratched open, leading to weeping and the ‘flowing out’ of fluid.

Even if there are no vesicles, a section of skin affected by eczema looked at under a microscope shows fluid between the skin cells, tending to push them apart. This produces an appearance reminiscent of a sponge – hence the term ‘spongiosis’ that is used by doctors.

All the different conditions called eczema would be expected to show this spongiosis, together with some degree of inflammation around superficial blood vessels, which are dilated, producing the hot, red feeling and appearance.

Is there a simple way of classifying eczema?

Unfortunately, no. There are many different causes and triggers for eczema – some from the outside world, for example irritants, allergy and bacterial infection, and others from within the body.

The ones from within are called ‘intrinsic’ and include ‘atopy’ – having a genetic tendency to eczema, asthma and hay fever – raised pressure in the leg veins, and reactions to stressful circumstances.

These causes and trigger factors are not mutually exclusive, so several may be important at the same time in the same person; it is, however, usually possible to give a general label to the main underlying cause.

As well as trying to provide an appropriate label, it is often useful to classify eczema in terms of how long it has been there and how quickly it appeared. Calling it ‘acute’ suggests a rapid onset and a short but maybe severe course; ‘chronic’ means continuing for a long time.

This time course may give some extra clues to the trigger or triggers involved. Most classifications are imperfect but do serve to show the different factors involved in producing similar changes in the skin. Eczema can be classified as follows:

1. Mainly caused by external triggers.

• Irritant – various chemicals, including detergents in soap.
• Physical factors – friction and chronic rubbing, sunlight and artificial ultraviolet light.
• Allergic – the immune system reacting to something coming into contact with the skin or taken by mouth.

2. Internal and other causes.

• Atopic – often associated with hay fever, asthma and food allergies.
• Seborrhoeic – related to yeasts on the skin, which has a specific pattern.
• Discoid – a descriptive term for rounded patches of eczema with no obvious cause.
• Venous/varicose/gravitational/stasis – a number of different terms for eczema on the lower legs owing to problems with the blood flow and pressure in the superficial veins, which can be varicose.
• Asteatotic – usually in elderly people and caused by excessive washing and dry, low-humidity environments. The skin takes on an appearance like crazy paving.
• Pompholyx – lots of very itchy blisters on the hands and feet.
• Neuro-dermatitis – often called lichen simplex, this is linked to chronic rubbing or scratching.

Is eczema the same as dermatitis?

Yes, and no! ‘Dermatitis’ is a more generalised word, simply meaning inflammation of the skin. All eczema is dermatitis, but many other conditions that can be called dermatitis fall within the grouping of dermatitis.

Most of the different types of eczema can, and often are, interchangeably termed dermatitis – the term is more commonly used in the USA. Previously more than now, an eczematous process caused by an irritant or allergic problem in the workplace was called contact dermatitis, and issues concerning compensation might at least have been implied.

For some types of eczema, it is more commonplace to use ‘dermatitis’. Cases include napkin (diaper) dermatitis, photodermatitis and neuro-dermatitis. For others, for example asteatotic eczema, ‘eczema’ has been the preferred term.

For some of the rest – such as seborrhoeic and discoid – eczema and dermatitis are used interchangeably. The situation is therefore still very confusing, and it is always worth asking your doctor if he or she means something different from your understanding of the words.

I had eczema as a child, but it cleared up until recently when I got it again on my hands. Why is this?

It sounds as though you have a form of eczema caused by contact with irritant chemicals. Not surprisingly, this is called ‘irritant contact eczema’, and it is the most common form caused by contact (perhaps 80% of cases), the other cause being allergic.

Strong irritants will cause an obvious and acute reaction on anybody’s skin, but weaker irritants need months or years of exposure to cause the same problems. As you have found, the eczema usually affects the hands and forearms as the most common parts of the body exposed to detergents, industrial oils, solvents, etc. Many people with dry or fair skin are likely to develop irritant problems, but your history of atopic eczema doubles the risk.

Is hand eczema different from other eczemas?

As far as the basic underlying process in the skin goes, it is the same as other types of eczema. It can be caused by a variety of different types of eczema, so the common thing is the site – on the hands.

A background of atopic eczema, wet work and contact seems to be the most important factor, and it affects women more than men. Environmental triggers from wet work and contact seem to be more important than any genetic factors.

It can be a very longlasting form of eczema, especially if it starts at a young age and is not caused by any specific allergies. It has been estimated to affect more than 1% of the adult population in the UK.

The health visitor says that my baby has cradle cap and that this is a type of eczema. Is this true?

Yes, this is a type of eczema called seborrhoeic eczema. It may affect infants but is rare during later childhood. It is probably most common in men.

It has several different patterns but most commonly affects the face and scalp in infants as well as the napkin area. Unlike atopic eczema, it does not feel itchy, so your baby won’t scratch very much. There are three main patterns:

• A red, scaly rash on the scalp and ears, around the nose and in the creases down to the lips and eyebrows. It is often associated with eczema in the ear canals and on the eyelids. This is the ‘cradle cap’ your health visitor is referring to.
• On the trunk in the centre of the chest and upper back. There is a dry, scaly rash sometimes accompanied by a more extensive outbreak of little bumps and spots around the hair follicles.
• An intertriginous form affecting the armpits, belly button and groins, which can also present under spectacles or hearing aids.

My baby has bad nappy rash despite regular changing and the use of a barrier cream. Could she have a form of eczema?

There are actually three types of eczema that can affect the nappy area. The most common is irritant eczema (nappy rash), which can affect nearly all babies to some extent. This simply reflects the fact that urine and faeces are irritant to the skin if left in contact with it for prolonged periods.

This type of nappy rash usually spares the skin right in the groins. The skin fold between the leg and the tummy therefore looks normal but is surrounded on either side by red, inflamed skin.

As you are already doing all the right things to prevent nappy rash, your baby may have one of the other types of eczema (atopic or seborrhoeic). Both of these tend to involve rather than spare the skin fold at the top of the leg.

Atopic eczema only rarely affects the nappy area and is normally very itchy. You may see eczema in the skin folds elsewhere on the body (e.g. in front of the elbows or behind the knees). In contrast, seborrhoeic eczema tends not to be itchy and tends to be associated with greasy yellow scales on the scalp (cradle cap).