What is the difference between atopic dermatitis and contact dermatitis?

Q:  What is the difference between atopic dermatitis and contact dermatitis?

A:  Atopic dermatitis appears early in life as chapped skin in areas that go through frequent wet-dry cycles (for example, the area around the mouth in babies) or in skin folds. Atopic dermatitis patients are susceptible to skin infections, which often make inflammation worse. Protein molecules, such as foods, or pollen or latex can penetrate broken and inflamed skin, and atopic patients are especially likely to develop an immune response to these types of allergens.  Irritant contact dermatitis can occur even in patients without a genetic predisposition to atopic dermatitis under extreme conditions. Examples of such conditions would be frequent wet work with harsh chemicals, such as the work done machine operators or hairdressers.  In any circumstance where skin is inflamed and broken, allergic contact dermatitis can develop to allergens in contact with the skin, such as components of topical medications, rubber in gloves, and preservatives or fragrances in personal care products.