The term eczema is broadly applied to a range of persistent or recurring skin rashes characterized by redness, skin edema, itching and dryness, with possible crusting, flaking, blistering, cracking, oozing or bleeding.
Eczema classification remains haphazard and unsystematized, and the proliferation of synonyms hinders understanding. At times, there is focus on the location (e.g. hand eczema), or on the specific appearance (eczema craquele or discoid), and other times on possible cause (varicose eczema). Further adding to the confusion, many sources use the term eczema and the term for the most common type of eczema (atopic eczema) interchangeably.
The four most common eczemas;
- Atopic eczema (aka infantile e., flexural e., atopic dermatitis) is thought to be hereditary, and often runs in families whose members also have hay fever and asthma. Itchy rash is particularly noticeable on face and scalp, inside of elbows, behind knees, and buttocks. Experts are urging doctors to be more vigilant in weeding out cases that are in actuality irritant contact dermatitis. It is very common in developed countries, and rising.
- Contact dermatitis is of two types: allergic (resulting from a delayed reaction to some allergen, such as poison ivy or nickel), and irritant (resulting from direct reaction to, say, a solvent). Some substances act both as allergen and irritant (e.g. wet cement). And some substances cause a problem after sunlight exposure, bringing on phototoxic dermatitis. About three fourths of contact eczema are of the irritant type, which is the most common occupational skin disease. Contact eczema is curable provided the offending substance can be avoided, and its traces removed from one’s environment.
- Xerotic eczema (aka asteatotic e., e. craquele or craquelatum, winter itch, pruritus hiemalis) is dry skin that becomes so serious it turns into eczema. It worsens in dry winter weather, and limbs and trunk are most often affected. The itchy, tender skin resembles dry cracked river bed. This disorder is very common among the older population. Ichthyosis is a related disorder.
- Seborrheic dermatitis (aka cradle cap in infants, dandruff) causes dry or greasy scaling of the scalp and eyebrows. Scaly pimples and red patches sometimes appear in various adjacent places. In newborns it causes a thick, yellow crusty scalp rash called cradle cap which seems related to lack of biotin, and is often curable.
Less common eczemas include;
- Dyshidrosis (aka dyshidrotic e., pompholyx, vesicular palmoplantar dermatitis, housewife’s eczema)
- Discoid eczema (aka nummular e., exudative e., microbial e.)
- Venous eczema (aka gravitational e., stasis dermatitis, varicose e.)
- Dermatitis herpetiformis (aka Duhring’s Disease)
- Neurodermatitis (aka lichen simplex chronicus, localized scratch dermatitis)
- Autoeczematization (aka id reaction, autosensitization)
- eczemas overlaid by viral infections (e. herpeticum, e. vaccinatum), and eczemas resultant from underlying disease (e.g. lymphoma).
- Eczemas originating from ingestion of medications, foods, and chemicals, have not yet been clearly systematized. Other rare eczematous disorders exist in addition to those listed here.
