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PHOTODERMATITIS - CHRONIC ACTINIC DERMATITIS

Chronic Actinic Dermatitis (CAD) comprises a broad range of abnormal reactions of the skin to ultra violet or other visible light radiation. The reactions cause inflammation, sunburns and occur on sensitized skin, where the sensitizers could be both external and internal agents.

It occurs mostly in people who are allergic to sensitizers, such as, flowers, types of wood, perfumes, sunscreens and rubber compounds. More than half the patients with chronic actinic dermatitis have a pre-existing allergic contact dermatitis or an endogenous condition like atopic or seborrheic dermatitis.

It affects mainly the exposed areas of the body. However, if UV light is the cause, then even the unexposed areas can be affected, unless the clothing totally blocks the light. The shaded areas affected, like, eyelids, points to associated allergic contact dermatitis.

Chronic actinic dermatitis probably occurs worldwide, but in places, it may remain undetected due to lack of diagnostic facilities. All skin types are affected including black African – African Americans. It is common among the elderly but youngsters between 12 to 14 years old are being increasingly affected.

In some patients, chronic actinic dermatitis clears after a long time, but it tends to remain unresolved in 80% patients, even 10 years after diagnosis. The prognosis for the associated contact allergic dermatitis is even worse, with some predicting chronic actinic dermatitis. However, it is not a life threatening disease, but management of chronic actinic dermatitis requires significant changes in life style to avoid certain allergens and sunlight.

Symptoms

Symptoms include occurrence in areas exposed to sunlight or applied with medications. The milder form looks like sunburn with the skin showing redness, itchiness and scaly skin in patches. If chronic actinic dermatitis occurs frequently, the skin may be thick and dark. In severe chronic actinic dermatitis, vesicles and bullae may be seen. Bullae are bubble like formations under the skin.

Risk factors

Risk factors include sunlight, diseases like porphyria and drugs like birth control pills, phenothiazines, tetracycline sulfonamides, diuretics and thalidomide.

Clinical features

The abnormal reactions consist of persistent light reactivity, actinic reticuloid, photosensitive eczema and photosensitivity dermatitis.

Causes

The causes of chronic actinic dermatitis remain unknown. Whatever be the cause cited, it must consider the broad range of chronic actinic dermatitis reactions, the presence of allergic dermatitis in chronic actinic dermatitis patients, its incidence in those with dermatitis, and its higher incidence in elderly men.

Some of the causes given are:

Phototoxicity, where the direct effect of the UV rays or taking chemicals or substances that make the skin more sensitive to UV light, can cause reactions.

Photoallergicity, where reactions occur when individuals exposed to sun are also taking certain chemicals or medications that make their skin allergic to sunlight.

Polymorphous light eruptions where the skin on exposure to sunlight, develops a red rash, hives which are flat or raised red areas with irregular borders, and vesicles which are small fluid filled bumps.

However, since all these causes are still hypotheses in need of confirmation, for the present it is best to regard chronic actinic dermatitis as a condition where an individual develops, for reasons unknown, increased allergic susceptibility to some external and internal photo sensitizing agents.

Diagnosis

Since chronic actinic dermatitis is caused by sunlight as well as artificial UV light from tanning beds, it can be difficult to find the source of the problem. One helpful way to proceed with the diagnosis is to check the condition of the unexposed parts of the skin as, for example, the skin under a watchstrap or bracelets.

Further diagnosis is done by photo testing, which consists of having various areas of skin exposed to known amounts of light of specific wavelengths and comparing the resulting reactions with that caused by the disease. The procedure is painless and can be repeated to assess improvement.

Patch testing is another common way of confirming chronic actinic dermatitis diagnosis. A range of chemicals is applied to the skin and left for two days. The skin is then examined for reactions.

Skin biopsy may be required if there is an underlying medical problem.

Treatment

Since external agents are involved in causing chronic actinic dermatitis, an avoidance protocol is essential. This consists of avoiding direct exposure to sunlight, as well as medications and topical creams that cause the problems. Wearing hats, long sleeves and using sunscreen are good ways to avoid UV radiation in sun light. A broad-spectrum zinc oxide sunscreen is recommended. Protective plastic film on home and car windows may be used.

For sunburns, cold water, ice compresses and aloe vera lotions can have soothing effects. In case of pain, aspirin may be taken. Corticosteroid creams (Betamethasone 0.1%) can ease the pain, redness, and itching of the inflammation. Topical steroids may be used in case of flares. High potency steroids should be used for short periods. For severe cases, prednisone pills can be a good medication.