Skin biopsies show inflammatory cells and swelling. When dermatitis becomes subacute, the intense reaction becomes milder, and the blisters begin to heal. Crusts and scale are common at this time. Chronic dermatitis is identified by thickened, leathery skin with excess ridges, as well as dark and dull skin. There is a wide range of dermatitis types.
Atopic dermatitis is an inherited condition characterized by dry, sensitive, itchy skin.
Infants and children are most affected, and the disorder can continue into adulthood. Contact dermatitis is caused by an irritation or an allergy and occurs on areas of the skin that have come in contact with the identified substance. These reactions can be sudden and severe, such as with poison oak or poison ivy, or more insidious and chronic, such as from repeated exposure to harsh soaps or chemicals. Seborrheic dermatitis is a fairly common condition seen mostly in adults and has a tendency to affect men more than women. The disease has a natural waxing and waning course.