Many people think of dermatitis as synonymous with eczema, however almost any rash can be thought of as a dermatitis including psoriasis, skin cancer, and seborrhea.

There are several distinct types of dermatitis that are defined by the agent or mechanism responsible for the rash. Examples of specific types of dermatitis are:

• Allergic contact dermatitis - A delayed hypersensitivity reaction involving allergens and antibodies. Irritant contact dermatitis - Exposure to irritating chemicals or detergents.
• Atopic dermatitis - An allergic-type reaction that is accompanied by hay fever, asthma, and very dry skin.
• Stasis dermatitis - Occurs on the ankles and lower legs of people with venous insufficiency.
• Diaper dermatitis - A type of irritant dermatitis caused by long exposure of the skin to wet diapers.
• Dyshidrotic dermatitis (pompholyx) – A type of dermatitis on the hands or feet that is characterized by redness, scaling, and deep blisters.

Dermatitis is usually diagnosed clinically based on the history and appearance of the rash. It is often difficult to tell the difference between types of dermatitis: there are very few tests performed that can specify an exact cause. Some examples of tests that may help with diagnosis are skin tests for contact or atopic dermatitis or a KOH test identifying a fungal infection.