Dermatitis is a term often used to denote an inflammation of the skin. In its acute stage, dermatitis is characterized by redness, itching, and either blister formation or oozing. In its chronic form, dermatitis is characterized by a thickening and increased pigmentation of the skin and the formation of scales.
Usually the term "dermatitis" is used interchangeably with the term "eczema". Sometimes, however, "dermatitis" refers to an inflammation whose cause is known, while "eczema" is reserved for a skin inflammation whose cause is undetermined.
There are many different types of dermatitis. Probably one of the most common forms is contact dermatitis, which is caused by a substance that comes into contact with the skin. This substance may be an irritant, such as soap, that produces an inflammation when applied to the skin often enough. Sometimes the causative agent is a substance that is harmless to most people but induces an allergic reaction in others. Among the substances that are particularly allergenic and thus frequent causes of contact dermatitis are the metals nickel and chromium, the antibiotic neomycin, and catecholamine, the substance produced by poison ivy. In all forms of contact dermatitis, a cure may be brought about by eliminating the offending substance or replacing with a specially formulated natural hypoallergenic soap.
Another form of dermatitis is atopic dermatitis, a condition that tends to run in families whose members also have asthma and hay fever. The rash, which starts within the first year of life, primarily involves the neck and the bends of the elbows and knees. The basic characteristic of atopic dermatitis is an excessive dryness of the affected skin, often leading to itchiness.
Stasis dermatitis occurs on the inner side of the legs, usually starting near the ankles. The underlying cause is an inadequate venous drainage of the legs, usually resulting from varicose veins or thrombophlebitis. The affected skin becomes heavily pigmented and tends to develop painless ulcers that heal slowly. The successful treatment of stasis dermatitis rests on the alleviation of the underlying circulartory problem.
Neurodermatitis is the term applied to any form of dermatitis that seems to have no cause other than the patient's own rubbing and scratching. When it occurs as a chronic condition, it appears as a patch of thick, heavily pigmented skin with exaggerated surface markings. Neurodermatitis is treated by applying cortico-steroid preparations.
A few skin conditions are called "dermatitis" even though they are not manifested as dermatitis. For example, dermatitis medicamentosa refers to any skin lesion, such as hives or blisters, that is caused by the administration of drugs.