What is eczema?
Eczema or dermatitis are the terms used to describe a group of dermatological diseases that cause inflammation or irritation of the skin.
Clinically, eczema manifests itself as redness, itching, scaling, cracking, and rougher skin. In some cases, blisters may also occur.
Dermatitis is very common and accounts for up to one in every three visits to the dermatologist. About 10 to 20% of children and up to 3% of adults have some form of eczema.
Eczema is not a contagious disease. You will not “catch” eczema just because you have touched the sore or had close contact with someone with a dermatitis condition.
Although the exact cause of dermatitis is unknown, we do know that people who develop eczema do so because of a combination of genetic and environmental factors. When an irritant or allergen “activates” the immune system of a genetically susceptible individual, the body’s defense cells begin to behave inappropriately, causing the skin to become inflamed.
Contact dermatitis is a good example. It arises from direct injury to the skin after contact with irritating substances, such as acids, solvents, or detergents, or from an allergic reaction after contact with an allergen, such as costume jewelry, latex, or henna.
There are several causes of eczema. The most common are
- Atopic dermatitis.
- Contact dermatitis.
- Dyshidrotic eczema.
- Nummular eczema.
- Seborrheic dermatitis.
- Stasis dermatitis.
Atopic dermatitis, also known as atopic eczema, is the most common form of eczema. Very common in babies and children, it can also affect adults.
Contrary to what many people think, atopic dermatitis is not an allergic disease. It appears to arise because of a genetic defect in a skin protein, facilitating the appearance of inflammation and symptoms of itching, scaling, dry skin and redness.
The extensor surfaces of the joints, such as the elbow and knee fossae, are areas that are frequently affected, both in children and adults.
The treatment is mainly done with skin hydration and elimination of factors that favor the aggravation of injuries, such as heat, sweating, stress, sudden changes in temperature and exposure to certain chemical products or cleaning solutions.
Contact dermatitis, as the name implies, is a form of eczema that occurs when the skin comes in contact with a substance that causes an allergy or irritation.
In up to 80% of cases, contact dermatitis is triggered by substances that cause direct irritation to the skin. In only 20%, contact dermatitis is caused by an allergic reaction.
Irritants are products that cause dermatitis in virtually everyone, as long as there is sufficient contact with the skin.
Patients with irritative contact dermatitis are generally more susceptible, who develop eczema with less prolonged contact than the majority of the population. Detergents, alcohol, acids, some types of metals and rubber are examples of irritating substances.
Allergic contact dermatitis only appears when the person is allergic to the substance in contact with the skin. In these cases, only a small group of people develop this form of eczema. Nickel, henna, latex, deodorants are examples of substances that often cause allergic contact dermatitis.
Contact eczema usually causes intense redness and itching, which are more or less restricted to the place where the irritating agent was in contact.
The key to treating this form of dermatitis is to remove contact with the product that causes irritation or allergy.
Dyshidrosis, also known as dyshidrotic eczema, is a skin disease that causes lesions in the form of small, itchy blisters on the palms of the hands and soles of the feet.
These small blisters usually persist for 3 to 4 weeks and then disappear, causing the skin to peel off.
We do not know what causes dehydrosis, and in most cases a causative factor is not usually found. However, several risk factors have been identified. The most common are:
- Personal or family history of atopic dermatitis.
- Personal or family history of allergies.
- Exposure to nickel or cobalt
- Exposure to irritants
- Hyperhidrosis (excessive sweating)
- Tobacco smoking
- Exposure to the sun.
- Physical or emotional stress.
- HIV infection.
Treatment is by general care measures designed to reduce skin irritation. In more severe cases, corticosteroid ointments or tablets may be used.
Nummular eczema, also called discoid eczema, is a chronic inflammatory skin disease characterized by reddish, oval-shaped lesions ranging from 1 to 10 cm in diameter that itch and usually involve the extremities and/or trunk.
Most patients are over the age of 50, although individuals of any age can be affected.
The exact causes of nummular eczema are still unknown. Numerous factors have been implicated in the origin of the disease, including dryness and decreased oil production in the skin.
Treatment for nummular eczema involves general measures to reduce dryness of the skin and exposure to irritants, as well as corticosteroid ointments and phototherapy.
Seborrheic dermatitis is a fairly common and mild form of eczema. This form of dermatitis is a chronic inflammation that appears on areas of the skin that contain large numbers of sebaceous glands.
The lesions usually appear in areas with high oil production in the skin, such as the scalp, face, chest, ear canal, and back. When it affects the scalp, the production of dandruff is one of its most common signs.
The skin lesions are usually reddish plaques that itch and may flake off.
The causes of seborrheic dermatitis are not fully understood. The most accepted theory nowadays is that the oiliness produced by the sebaceous glands allows the creation of a favorable environment for the growth of fungi of the genus Malassezia (formerly called Pityrosporum ovale).
Mild cases, only with dandruff on the scalp, can be controlled with anti-dandruff shampoo only.
If there is no improvement with traditional anti-dandruff shampoos, a consultation with a dermatologist is necessary. The use of ointments, lotions or special shampoos with corticoids may be necessary to control the lesions.
Stasis dermatitis, also called gravitational dermatitis or venous eczema, occurs when the patient has lower-limb venous insufficiency, i.e. poor blood circulation in the leg veins, usually with multiple varicose veins.
Venous insufficiency occurs when the veins in the legs are diseased and cannot adequately drain blood back to the rest of the body, causing damming and increased pressure in the leg veins.
This increased pressure causes fluid to leak from the veins and skin, resulting in swelling and redness in the legs.
Symptoms of stasis dermatitis include:
- Swelling in the legs, especially in the feet and ankles.
Treatment of the patient with stasis dermatitis involves treating the chronic venous insufficiency, skin dryness, itching, and inflammation.
- Overview of dermatitis (eczema) – UpToDate.
- Acute palmoplantar eczema (dyshidrotic eczema) – UpToDate.
- Stasis dermatitis – UpToDate.
- Eczema – Medline Plus – US National Library of Medicine.