Eczema is an umbrella term that covers several types of skin inflammation, according to MedlinePlus, an online medical encyclopedia sponsored by the U.S. National Library of Medicine. Another name for eczema is dermatitis. Eczema is not an infection and the skin disorder has several different types. All types cause red, itchy and swollen skin.
Atopic Dermatitis
When people say "eczema," they are often referring to a specific type called atopic dermatitis. The National Institute of Arthritis and Musculoskeletal and Skin Diseases describes atopic dermatitis as a chronic, long-term skin disease that causes dry, itchy skin and rashes inside the elbows, behind the knees and on the hands, feet and face. Scratching the skin causes it to become swollen, red, cracking, scaling, crusty and thicker. Clear fluid may also leak from the wounds. Even though it is a long-term skin disorder, it has periods during which symptoms get worse or even clear up. The cause of atopic dermatitis is unknown, but it is most likely due to both genes and certain environmental factors.
Dyshidrosis
The Mayo Clinic describes dyshidrosis as another type of eczema, also called dyshidrotic eczema or pompholyx. This condition causes small blisters to appear on the hands or soles of the feet. These fluid-filled blisters generally last about three weeks once they appear, and they can be intensely itchy. The blisters can burst or dry out, and the resulting cracks can be painful. The cause of this type is unknown, but asthma and hay fever may accompany seasonal eruptions.
Seborrheic Eczema
According to the National Institute of Arthritic and Musculoskeletal Skin Diseases, seborrheic eczema causes yellowish patches on the skin that are often oily or scaly. The patches usually appear on the scalp and face, and may also appear on other parts of the body.
Nummular Eczema
The American Osteopathic College of Dermatitis reports that nummular eczema is characterized by very itchy coin-shaped patches on the skin. The patches may clear in the center as they get older, or they may become scaly. The older lesions may resemble ringworm or psoriasis patches. The cause of this type of eczema is generally unknown, though it is occasionally caused by an allergy to medication. The condition is usually chronic.
Contact Eczema
This type of dermatitis forms a patch of itchy and inflamed skin at one defined location on the skin, and is due to an allergy to a particular substance that has come into contact with the skin. Typical substances that cause contact eczema are cleaners, acids and other chemicals.
