What are the different types of eczema?

There are a number of types of eczema. These are categorised as follows:

• Atopic dermatitis – This health disorder is the most common form of eczema and is thought to have a genetic influence. Atopic dermatitis will typically begin to show symptoms early in the lives of those who have a predisposition to inhalant allergies (hay fever and asthma). The rash will normally occur on the neck, elbows, knee creases, cheeks and ankles.
• Contact dermatitis – This is caused by a substance coming into contact with the skin and causing irritation or triggering an allergic reaction. There are two different types of contact dermatitis:
  • Irritant dermatitis – This kind of eczema occurs as a result of the skin being exposed to an irritant, toxic substance or due to excessive washing. An example of this is would be certain detergents, perfumes or bleach. This form of contact dermatitis is not caused by an allergen, but it is rather a reaction to a substance that causes irritation to the skin.
  • Allergic contact dermatitis –People with this form of eczema will develop an allergic reaction when they are exposed to a foreign substance. An example of this is a latex allergy. In allergic contact dermatitis, when a substance touches the skin, the immune system will overreact and recognise this substance as an allergen (even though it should not be considered one), which it perceives as a threat to the body. It then creates a specific type of antibodies as a defence mechanism to fight off the invader (allergen). The result of this reaction is inflammation which causes a red, itchy rash at the site where the substance came into contact with the skin.
• Dyshidrotic dermatitis – This form of eczema occurs in teenagers and adults and results in small fluid-filled blisters, known as vesicles, forming on the hands and feet. The blisters are often a result of damp hands and feet, allergies, stress or substance-exposure. The rash may hurt or itch and the skin may begin to crack, flake or scale. The first symptom of dyshidrotic dermatitis is usually itching, followed by blisters and then scaly patches. Some people may also experience deep cracks appearing on the hands or fingers. The cause of this condition is unknown.
• Lichen simplex chronicus (LSC)/neurodermatitis – This form of eczema results in thick and scaly patches popping up on the skin, similar to those experienced in atopic dermatitis. These patches of skin are often extremely itchy and tend to form on the arms, back of the neck, legs, scalp, bottoms of the feet or backs of the hands and even genitals.
• Neurodermatitis develops as a consequence of skin irritations forming in spots that are frequently scratched. A number of people may scratch these areas without realising and even scratch while they are sleeping. Infections may also develop in the irritated areas. The exact cause of neurodermatitis is unknown.
• Seborrheic dermatitis – This form of eczema results in the development of papules (small pimples or bumps) and scales and affects the sebum-rich (i.e. oil producing) areas of the body such as the face, scalp and trunk. It can causemild to severe dandruff or an inflammatory condition known as exfoliative erythroderma (widespread reddening and scaling of the skin that affects up to 90% of its surface).
  
  In cases of eczema related dandruff, the area affected in infants and children is typically the scalp. Adults with the condition may also have dandruff of the scalp as well as in their eyebrows, on the sides of their nose, behind the ears, the centre of their chests and even the groin.
  
  Seborrheic dermatitis results in the skin flaking and falling off and while researchers are still trying to determine the exact cause of the condition, they believe a number of factors may be at play in its development. These include a combination of a low T-cell count (T-cells play a role in immune system function) and activation of the immune system (known as the alternative complement pathway), as well as elevated sebum levels (resulting in greater oil production). It is thought that the overgrowth of a certain form of yeast that usually lives within the areas in which this condition occurs and an overgrowth of cells that rapidly shed are also contributing factors. Some medications like auranofin, chlorpromazine, fluorouracil, lithium and methyldopa (amongst many others) may lead to the development or cause flare-ups of this type of dermatitis.
• Stasis dermatitis – This form of eczema occurs on the lower legs of those who are middle-aged or older and have poor circulation in their leg veins. This causes a build-up of pressure in the veins and fluid leakage into surrounding tissues and skin which leads to swelling, redness, itching, scales and pain. Stasis dermatitis tends to develop rapidly, resulting in the crusting and weeping of the person’s skin, over time the rash may result in the development of brown stains on the skin.
• Nummular dermatitis – This type of eczema tends to commonly affect more men than women. Men will usually have their first outbreak of nummular dermatitis after their 50’s with women suffering from the condition during their early adult years. The symptoms of the rash will manifest through red-shaped coin marks on the backs of hands, legs forearms, hips and lower back. Factors which may contribute to its development include extremely dry skin, weather conditions (especially winter), contact allergies, emotional stress and problems with nutrition.

Other conditions resembling eczema

• Scabies – This condition is the result of skin infestation by the human itch mite and may often cause a rash similar to that of eczema.
• Fungal infections – Some fungal infections may create an extremely similar pattern to those of other forms of eczema, however, in these instances the fungus can be identified by a scraping being examined under a microscope or grown in culture and eczema is then ruled out.