What is eczema?
Eczema refers to any skin inflammation and irritation where the skin becomes dry, rough to touch and usually red and peeling. The most common type of eczema is atopic dermatitis often seen in babies and young children with allergies. The term eczema is widely used to describe a number of skin rashes. It is synonymous with the term “dermatitis” (eczematous dermatitis) which refers to various inflammatory conditions of the skin and can be acute or chronic.
Eczema is often thought of only as atopic dermatitis, a skin condition commonly affecting infants and children due to immune-mediated hypersensitivity. Eczema, and even atopic dermatitis, can affect any group including adults and the elderly . The characteristic feature of eczema is persistent itching, which exacerbates and is intolerable in acute aggravations.
How does eczema start?
There are a range of possible causes of eczema. Sometimes there is genetic susceptibility meaning that the genes that are inherited makes a person sensitive to certain irritants. The immune system may be hypersensitive and manifest on the skin or an irritant disturbs the normal skin function and health. The underlying feature in most cases, however, is the influence of the immune cells and chemicals.
The immune system is the body’s defense against injury and foreign invaders like germs. It is activated once the presence of harmful chemicals and germs are detected. Immune chemicals trigger certain processes at the site and immune cells aggregate towards it. While it is intended to protect the body, it is also a process that can cause significant irritation. Normally it limits the extent of this defensive reaction until the foreign chemical or germ is neutralized or destroyed.
However, with certain conditions the immune system is abnormally triggered into action even when there is no irritant or threat. In an allergy, the body is sensitive to certain foods or airborne substances which are not harmful. If the immune protection in the skin is abnormally activated then the inflammation will be evident on the skin. Sometimes there are actual irritants in the environment although this will not cause such an exacerbated reaction in every person.
What does eczema look like?
All types of eczema initially appear as red, flat or dome-shaped skin lesions (papules) that are often fluid-filled (vesicles) and less than 5 millimeters (mm) in diameter although large blisters greater than 5 millimeters (bullae) may also be seen. Underlying swelling (edema) of the dermis extending into the epidermis known as spongiosis gives the affected area a raised appearance. Itching is intense and breaks in the skin (excoriations) may be seen due to scratching. The vesicles may rupture and therefore appear as oozing and crusted lesions especially if there is a superimposed bacterial infection which further contributes to the presentation. It is often referred to as “wet” eczema in this stage.
Picture from Wikimedia Commons
In the chronic setting, there are little or no vesicles of bullae and oozing and crusting is not seen except in acute bacterial infections. Instead the skin appears red, thick (epidermal thickening ~ acanthosis) and scaly (hyperkeratotic). There is excessive dryness and persistent itching. The presentation, especially in the chronic setting, may vary slight among the different types of eczema.
Picture from Dermatology Atlas (Courtesy Samuel Freire da Silva, M.D.)
Types of Eczema
There are several types and sub-types of eczema. Broadly based on the causative factors, eczema can be classified into allergic contact, atopic, drug-related, photoeczematous and primary irritant dermatitis. The different types of eczema include :
- Atopic dermatitis
- Contact dermatitis – allergic contact dermatitis and primary irritant contact dermatitis.
- Dyshidrotic dermatitis – pompholyx
- Seborrrheic dermatitis
- Neurodermatitis – lichen simplex chronicus
- Nummular dermatitis – discoid
- Stasis dermatitis – gravitational
- Occupational dermatitis
- Asteotic dermatitis
The appearances of these different types of eczema may vary and so does the causes of eczema and underlying disease process. However, the common feature is that all eczemas present with inflammation which is evident as lightly swollen skin, rough skin, dryness or excessive oiliness, itching and at times heat when it is severely inflamed.
The treatment of eczema depends on the type of eczema. Often lifestyle changes in terms of avoiding certain food and contact with irritants and allergens are sufficient to limit the condition. However, there are various types of medication that may be prescribed by a doctor.
- Antihistamines reduce the immune chemicals and eases symptoms like itching.
- Corticosteroids suppress the immune system which helps bring down the inflammation. This is available in oral (tablets or capsules) and topical (creams and ointments) medication.
- Emollients help to protect the skin and restore the normal protective function of the skin. This allows the skin time to heal and reduces any further irritation from the environment.
These are just some of the more commonly prescribed medication that is used in most eczemas. There are other specific types of drugs that will only be used in certain skin conditions. It is important that the skin is first examined by a doctor, and preferably a dermatologist, before treatment is commenced. Many eczemas look similar and it may be difficult to differentiate between them without professional medical advice.