Dermatitis is a general term that describes an inflammation of the skin. There are different types of dermatitis, including seborrheic dermatitis and atopic dermatitis (eczema). Although the disorder can have many causes and occur in many forms, it usually involves swollen, reddened, and itchy skin. , a rash that results from either repeated contact with irritants or contact with allergy-producing substances, such as poison ivy., a chronic itchy skin condition localized to certain areas of the skin.