Author: Vanessa Ngan, Staff Writer, 2006.
Chronic actinic dermatitis is a rare skin condition that mainly affects men over the age of 50 years. It is characterised by severely itchy, red, inflamed, and thickened dry skin, mainly in areas that have been exposed to sunlight or artificial light. The condition is also known as chronic photosensitivity dermatitis and actinic reticuloid (this name comes from the histological findings of skin biopsies which resemble a reticulosis or cutaneous T-cell lymphoma).
Chronic actinic dermatitis mostly affects middle-aged or elderly men.
In many patients with the condition there is frequently a history of other kinds of dermatitis, including atopic dermatitis, allergic contact dermatitis (especially to plants such as chrysanthemum) and photocontact dermatitis for many years before the photosensitivity develops. In these cases it is sometimes called persistent light reaction
The rash may develop in all areas exposed to the sun, with the face, neck, upper chest in a V distribution and backs of hands most commonly affected. The lesions are usually red and inflamed with scaling and lichenification (thickened and hardened patches of skin). The rash can be very itchy. The rash may spread to other areas of the body where the skin is covered by clothing.
The rash can be provoked by as little as 30 seconds exposure to daylight. It is condition that is often present throughout the year. Patients are at risk even on dull days and through window glass. Some of them also react to artificial light sources, especially naked fluorescent lamps.
Testing shows chronic actinic dermatitis is due to abnormal reactions to UVB, UVA and in severe cases to visible light.
Phototesting can be used to confirm the diagnosis. This involves specialized tests in which areas of skin are exposed to known amounts of light of specific wavelengths. The reactions that develop confirm the presence of an abnormal reaction to the light.
Patch testing and photopatch testing are also used. It has been found that positive patch-test reactions to one or more allergens occur in 75% of patients with chronic actinic dermatitis, most often fragrance, sunscreens, colophony and a sesquiterpene lactones (found in the diasy family of plants).
Patients with chronic actinic dermatitis must take measures to avoid sun exposure by following sun protection strategies. In severe cases it may be necessary to admit the patient to a dark room in hospital.
In addition, if a contact allergy in involved the patient must try to avoid the offending substance.
Treatment also includes:
In severe cases, oral immune suppressive treatments may be required. These include:
The condition may spontaneously resolve, sometimes many years after the onset of the disease. For most people it is a lifelong condition that requires significant lifestyle changes to avoid sunlight as well as contact allergens.
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