Symptoms (signs) vary from person to person. The most common symptoms are dry, itchy skin and rashes on the face, inside the elbows and behind the knees, and on the hands and feet. Itching is the most important symptom of atopic dermatitis. Scratching and rubbing in response to itching irritates the skin, increases inflammation, and actually increases itchiness. Itching is a particular problem during sleep when conscious control of scratching is lost.
The appearance of the skin that is affected by atopic dermatitis depends on the amount of scratching and the presence of secondary skin infections. The skin may be red and scaly, be thick and leathery, contain small aised bumps, or leak fluid and become crusty and infected. Atopic dermatitis may also affect the skin around the eyes, the eyelids, and the eyebrows and lashes. Scratching and rubbing the eye area can cause the skin to redden and swell. Some people with atopic dermatitis develop an extra fold of skin under their eyes. Patchy loss of eyebrows and eyelashes may also result from scratching or rubbing.
Researchers have noted differences in the skin of people with atopic dermatitis that may contribute to the symptoms of the disease. The outer layer of skin, called the epidermis, is divided into two parts: an inner part containing moist, living cells, and an outer part, known as the horny layer or stratum corneum, containing dry, flattened, dead cells. Under normal conditions the stratum corneum acts as a barrier, keeping the rest of the skin from drying out and protecting other layers of skin from damage caused by irritants and infections. When this barrier is damaged, irritants act more intensely on the skin.
The skin of a person with atopic dermatitis loses moisture from the epidermal layer, allowing the skin to become very dry and reducing its protective abilities. Thus, when combined with the abnormal skin immune system, the person’s skin is more likely to become infected by bacteria (for example, Staphylococcus and Streptococcus) or viruses, such as those that cause warts and cold sores.
Skin Features Associated With Atopic Dermatitis
• Atopic pleat (Dennie-Morgan fold)—an extra fold of skin that develops under the eye
• Cheilitis—inflammation of the skin on and around the lips
• Hyperlinear palms—increased number of skin creases on the palms
• Hyperpigmented eyelids—eyelids that have become darker in color from inflammation or hay fever
• Ichthyosis—dry, rectangular scales on the skin
• Keratosis pilaris—small, rough bumps, generally on the face, upper arms, and thighs
• Lichenification—thick, leathery skin resulting from constant scratching and rubbing
• Papules—small raised bumps that may open when scratched and become crusty and infected
• Urticaria—hives (red, raised bumps) that may occur after exposure to an allergen, at the beginning of flares, or after exercise or a hot bath