Additional Clinical Features
There are a number of physical findings that, if present, support a diagnosis of atopic dermatitis. Most of these findings are not specific to atopic dermatitis and may also be seen in healthy patients without atopic dermatitis.
Persistent, generalized dry skin without inflammation is a hallmark of atopic dermatitis. The cause of the dry skin is unclear, but studies have shown increased water loss and impaired skin hydration in atopic patients when compared to controls.
This disorder is seen in 20 to 50 percent of atopic dermatitis patients and mainly affects the distal lower extremities. It is characterized by excessive, “fish-like” scaling. It can sometimes persist despite appropriate atopic dermatitis therapy. It may contribute to the itching in atopic dermatitis.
Hyperlinearity of palms and soles
Increased prominence of the lines on the palms and soles may be seen in atopic dermatitis patients. These findings are also commonly seen in association with ichthyosis vulgaris (see above).
These are extra creases or folds just below the lower eyelid that can be present in atopic dermatitis patients as early as birth. The finding is not specific to atopic dermatitis and may be seen in other inflammatory conditions that affect the area around the eye. If present, Dennie-Morgan lines support the diagnosis of atopic dermatitis when seen in association with other typical findings. They are often seen along with swelling and darkening (like a black eye) beneath the eyes, the so-called allergic shiners.
This very common condition is often seen in atopic dermatitis patients, but it is also seen in a large number of otherwise healthy children. Keratosis pilaris is caused by plugging of the hair follicles. It results in small bumps usually seen on the outside parts of the upper arms and thighs. The cheeks may be involved as well, especially in young children. The bumps may become inflamed (red, warm, tender) but are, most commonly, flesh-colored and do not cause the patient any problems. The condition is strongly associated with dry skin (xerosis), also seen in atopic dermatitis. Treatment is aimed at hydrating the skin with emollients and/or lactic acid preparations.
This is an associated condition often seen together with atopic dermatitis that results in patchy areas of hypopigmentation (lightening of the skin) covered with fine scale. The patches most commonly occur in sun-exposed areas such as the face and extremities. The lesions are the result of a low-grade inflammatory process. Pityriasis alba is more noticeable in darkly pigmented and/or tanned individuals. It can be treated with emollients and low-potency topical steroids or calcineurin inhibitors for more bothersome cases. Parents should also be counseled regarding use of sunscreen to lessen the appearance of contrasting colors between healthy and involved skin.
Cracks, crusting, and scaling of the corners of the mouth or dry, chapped lips are commonly seen in patients with atopic dermatitis.
Lichen simplex chronicus
Lichen simplex chronicus is a result of repeated rubbing and scratching of the skin. It can be due to itching of any cause, including atopic dermatitis. It often begins with a small bump but then grows into a thickened, larger area. The skin has a leathery appearance with exaggeration of the natural skin markings. Lesions of lichen simplex chronicus often occur on the neck or backs of the hands, feet and ankles. Treatment consists of topical steroids to control itching. A dressing to prevent scratching may also be necessary to allow for healing.
Prurigo lesions are commonly seen in atopic patients. They are thickened, reddish bumps that tend to localize to the arms and/or legs. As opposed to lichen simplex chronicus, which results from scratching, prurigo nodules are the result of chronic picking of itchy, irritated skin.
Atypical vascular reactivity
Although not specific to atopic dermatitis, patients often show what is called atypical vascular reactivity. Paleness of the face is one commonly seen example of this phenomenon. So-called white dermatographism is another example (white line that appear on the skin within one minute of being stroked).
A number of eye findings have been described in association with atopic dermatitis. Itching and sensitivity to light are the most common. Chronic red, itchy eyes may also be seen, sometimes in association with allergic runny nose. Cataracts have been described and tend to occur in older patients, generally in association with more severe cases of atopic dermatitis. An abnormally-shaped cornea (keratoclonus) occurs infrequently and in very severe cases. Cataracts and keratoclonus are thought to be caused by chronic rubbing in response to inflammation.