What is Eczema?

Eczema is a form of dermatitis, or inflammation of the epidermis. The term eczema is broadly applied to a range of persistent skin conditions. These include dryness and recurring skin rashes which are characterized by one or more of these symptoms: redness, skin edema (swelling), itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding. Areas of temporary skin discoloration may appear and are sometimes due to healed lesions, although scarring is rare. In contrast to psoriasis, eczema is often likely to be found on the flexor aspect of joints.

Causes

There are several types of eczema that look quite similar but have different causes and require different treatments. Contact dermatitis can be divided into two distinct problems, which are referred to as direct irritant contact dermatitis and allergic contact dermatitis. The former term refers to exposure to acids, alkaline mixtures, detergents and various other chemicals that acutely inflame the skin. The condition can become chronic with repeated exposure. This form of dermatitis is often encountered in the workplace.
Allergic contact dermatitis is caused by exposure to an allergen that sensitises the skin leading to acute inflammation when re-exposure occurs. This of course can also be due to a food allergy reaction. A crucial distinction between the two is that prior exposure to the agent is necessary for allergic contact dermatitis to occur whereas direct irritant contact dermatitis can occur at the first exposure. For example, most people will develop dermatitis on first exposure to strong chemicals that are acid or alkaline in nature.

Other types of eczema arise as a result of causes within the body. These include: atopic eczema, seborrhoeic dermatitis, discoid or nummular eczema, pompholyx or dishydrotic eczema, and varicose dermatitis also known as stasis eczema. Other similar conditions, which are caused by internal factors, include juvenile plantar dermatosis and lichen simplex. Eczema can cause a wide range of symptoms.

Symptoms

All types of eczema cause itch, with the exception of seborrhoeic. The main symptoms (one or all may be present) include: redness, weeping skin, pain, heat, tenderness, scaling, crusting, dryness, fissures (broken skin) and vesicles (small blisters) occur.

Over time, damage to the epidermis, the upper layer of the skin, can cause it to thicken and become scaly. This process is referred to as lichenification.