Basic Information:

Dermatitis describes a skin disorder usually typified by superficial scaling, redness papules and swelling. These skin disorders are associated with unknown factors and many of them are difficult to diagnose because of the similarities among the different rashes.

Atopic dermatitis (atopic eczema), seborrheic dermatitis (which includes common dandruff of the scalp) and psoriasis are among the major dermatoses that are endogenous (malfunctioning skin). These disorders are inclined to spontaneous worsening (or remission) which may be due to irritants such as soap, detergents or abrasive cleaners. These external factors influencing dermatitis are described as exogenous. Most dermatoses, including those named above, are thought to result from a combination of endogenous and exogenous factors.

Dermatitis also refers to skin rashes whose origin is known and result from exposure to environmental substances. Poison oak or poison ivy would be an example of this sort of rash. This kind of dermatitis is called allergic contact dermatitis. Contact dermatitis is quite common. It can be caused by an allergy to or irritation stemming from the skin coming into contact with certain clothing or materials such as wool. It is estimated that over half of Americans have experienced some form of contact dermatitis.

Psoriasis:

This is a chronic, itchy skin disorder that also runs in families -- the lesions are slightly raised, whitish scales with pink or reddish margins. It is a chronic condition that affects up to 2% of the U.S. population. Men and women seem to be equally affected, though the African American and Native American population, as well as the Asian population, are less affected than whites. Like eczema psoriasis usually begins in childhood and can re-appear chronically in adulthood. It can appear at the site of a physical disturbance (sunburn or intense scratching or minor injury). Stress or infections can also activate this chronic disorder, an episode of which can last for a few days up to a few months. The psoriasis can be mild to quite severe and is not contagious, nor is it curable, only controllable.

Seborrheic Dermatitis:

This is a genetically acquired scaling rash that is harmless and quite common. We are familiar with seborrheic dermatitis of the scalp -- it is called dandruff. Seborrheic dermatitis can also appear on:

• the eyebrows;
• the earsl;
• the armpits;
• the groin;
• the chest (patches);
• the back (patches).

This rash runs in families, is not contagious and its cause is unknown. Stress appears to contribute to its appearance, but it can be chronic, coming and going at any age, getting better or worse seemingly at will, with no known factor to point to.

Contact Dermatitis:

As discussed above, contact dermatitis is the result of exposure to environmental substances and can be divided into two groups:

• Irritant contact dermatitis
• soaps, detergents;
• shampoos and hair tints (beauticians);
• ragweed;
• rubber -- rubber gloves (medical);
• cement (construction workers);
• certain clothing.

Allergic contact dermatitis:

• poison oak;
• poison sumac;
• poison ivy;

also, but less frequent:

• formaldehyde (cosmetics);
• nickel (jewelry).

With irritant contact dermatitis, dry fissures and swelling or inflammation occurs. Allergic contact dermatitis can present with blisters whose pattern is usually asymmetric. One-fifth of dermatitis cases in young children are caused by allergic contact dermatitis.