dermatitis (dûrˌmətĪˈtĭs) [key], nonspecific irritation of the skin. The causative agent may be a bacterium, fungus, or parasite; it can also be a foreign substance, known as an allergen. Contact dermatitis is an allergic reaction to a substance that comes in contact with the skin, such as soap. Atopic dermatitis, also known as eczema, is a chronic, itching inflammation that tends to run in families susceptible to asthma and hay fever. Stasis dermatitis, or eczema of the legs, is caused by poor circulation and is found in older persons suffering from vascular disorders. When dermatitis is chronic it tends to cause thickening, pigmentation, and scaling, and when acute, a red, itching area of blisters and oozing.