In the strict sense dermatitis simply means inflammation of the skin. The inflammation can be caused by chemical irritants such as solvents or detergents, allergens such as resin from poison ivy plants, superficial yeast or bacterial infections, and genetic tendencies toward dryness of the skin and sensitivity to changes in climate called atopic dermatitis.
Psoriasis is not included with dermatitis. Although it is also marked by redness indicating inflammation, the rapid turnover of skin cells is the predominant abnormality which leads to thickness and scaling of the lesions.
The most common types of dermatitis are seborrheic, allergic, and atopic.
Seborrheic dermatitis consists of light scaling on the scalp also known as dandruff and redness with yellowish greasy flakes on the face, especially in the eyebrows, sides of the nose, behind the ears, and in the moustache and beard areas of men. Mild cases are controlled by over the counter anti-dandruff shampoos and facial moisturizers or 1% hydrocortisone cream. Recently, it was learned that a certain type of yeast is found growing in the scales of seborrhea, and that treatment is vastly improved with the anti-yeast shampoo and cream containing 2% ketoconazole.
The best example of allergic contact dermatitis is the reaction to the resin in poison ivy plants. The rash consists of red raised bumps in lines or blotches with small clear fluid filled blisters on top. The rash is very itchy, and the skin sometimes weeps fluid. The rash develops 2-14 days after contact with the responsible substances. Other commonly encountered skin allergens that cause dermatitis include nickel in costume jewelry (think of unexplained rashes on ear lobes, necks, and fingers), neomycin, the popular topical antibiotic found in triple-antibiotic Neosporin ointment, as well as fragrances and preservatives found in scores of cosmetics, sunscreens, and prescription medicines.
The skin rash may be treated with either topically applied high potency cortisone creams or prednsone pills and shots. Antihistamines such as benadryl and anti-itch creams may be used to reduce the symptoms. The prevention of allergic contact dermatitis requires determining the cause and eliminating it from the environment if possible.
Probably the most difficult to treat dermatitis is the most common dermatitis known as atopic dermatitis or eczema. This condition affects about 4% of the population at some time in their lives, and is more common and more severe in children. The word atopy refers to an increased sensitivity to the environment including temperature, humidity, textures of clothing, and allergens in foods and in the air. An atopic person is also more likely to have asthma, food sensitivities, and be allergic to penicillin. The atopic tendency is a genetic trait, that is, it is inherited. Any of the features may be inherited singly or together. In other words, the allergies do not cause the eczema; they are separate components of the atopic tendency.
The rash begins as dry itchy skin. In very young children the face and diaper areas are affected first with redness. Later the skin folds of the neck, wrist, elbow and knee creases are attacked with scratch marks, accentuated skin lines, and breaks in the skin leading to infection. In adults, the eczema persists as hand dermatitis aggravated by wet work, soaps, cleaning agents, and food preparation.
Treatment has to be tailored to the individual case based on age, but generally consists of the combination of reduced bathing and exposure to water, use of gentle or super-fatted soaps, liberal use of bland moisurizers, antihistamines for itching and to help sleeping through the night. More severe cases require topical or oral antibiotics, medium to high potency corticosteroid ointments, or internal steroids such as short-acting prednisone or intramuscular injections of long-acting Kenalog. Newer non-steroidal creams for eczema suppress the local inflammation. These calcineurin inhibitors are named Elidel and Protopic and are only available by prescription. Chronic cases of eczema may also be helped by graded sun exposure. If so, then our narrow band ultraviolet B lamps in the office will also reduce itching and promote healing of the skin.
