Scaly patches of skin not caused by infection

Scaly, itchy skin patches often represent one of the conditions referred to as eczema.

Atopic dermatitis: Atopic dermatitis is perhaps the most common form of eczema. This is a hereditary skin problem that often begins in childhood as chapped cheeks and scaly patches on the scalp, arms, legs, and torso. Later in childhood, atopic dermatitis may affect the inner aspects of the elbows and knees. Adults get atopic dermatitis on the hands, around the eyelids, on the genitals, as well as on the body as a whole.

The word "dermatitis" means inflammation of the skin. "Atopic" refers to diseases that may be associated with allergies and tend to run in families. Atopic diseases include asthma, hay fever, and atopic dermatitis. In fact, people may refer to what doctors call eczema as "allergic skin." However, this is usually not the case. Patients with atopic dermatitis may have allergies, but most cases of atopic dermatitis are not themselves allergic.

Eczema comes and goes on its own schedule, in a manner not related to the allergy usual suspects—foods, soaps, and detergents—which may be blamed for flare-ups. In most cases, changing diet and detergents helps eczema very little.

Atopic dermatitis is often worse in the winter months, when the air is cold and dry, so that frequent washing may irritate the skin and aggravate the condition Although the skin feels "dry," it really isn't; it is inflamed, and therefore moisturizing alone does not help much.

Skin affected by atopic dermatitis becomes extremely itchy and inflamed. It may look red, swollen, and cracked. In some cases, the skin can also weep and crust. Liquid that oozes out of such crusts is often not infected; what comes out is the body's normal tissue fluid. Treatment specific for eczema is helpful, not antibiotics.

Patches of atopic dermatitis may appear on various parts of the body, but the condition is not contagious. It may appear off and on throughout life, but there may be long intervals between outbreaks. Also, the condition does not get progressively worse with age; if anything, it is most extensive during childhood.

Treatment of eczema involves minimizing irritation if that is contributing to the problem and using prescription-strength steroids (cortisone creams). Nonsteroidal creams like tacrolimus (Protopic) and pimecrolimus (Elidel) have become less popular both because of relative lack of effectiveness and concerns about safety. Tap water soaks with Burow's solution (available without prescription) can help dry up atopic dermatitis in its oozy stages.

Contact dermatitis: Contact dermatitis is a rash that is brought on either by contact with a specific material that causes allergy on the skin or with something that irritates the skin, like too-frequent hand washing.

Common examples of contact dermatitis caused by allergy are poison ivy and reactions to costume jewelry containing nickel. With occasional exceptions, allergic contact dermatitis affects just those parts of the skin touched by whatever material causes the allergy, as opposed to atopic dermatitis, which can be widespread because, as explained above, it is not an allergy to a specific substance.

Treatment of contact dermatitis involves avoiding the allergen that caused it, if there is one, or minimizing whatever exposure is irritating the skin (water on the hands, solvents at work, saliva around the mouth from lip licking). Effective treatments include topical steroids, including over-the-counter 1% hydrocortisone and many prescription-strength creams. Here too, nonsteroidal creams like tacrolimus and pimecrolimus are used less than they once were. Tap water soaks with Burow's solution cab help dry up oozy contact dermatitis as well.

There are of course many other scaly rashes. Two worth mentioning are psoriasis, a hereditary condition affecting elbows, knees, and elsewhere, and pityriasis rosea, which primarily affects teens and young adults, producing scaly patches on the chest and back and generally disappearing in about a month. Xerosis, very dry skin, may also appear as a rash during the cold, dry months of the year.