Actinic keratosis is precancerous localized skin growths on sun-damaged areas.
Years of cumulative sunlight (ultraviolet) exposure damages skin and causes it to grow abnormally. Patches on skin pale or redden to produce a mottled appearance. Then rough, scaly, or crusted areas develop that are usually pink, but can be gray. Sometimes a small “horn” of fingernail-like material grows.
These lesions are more common in older men, probably related to occupational exposure. They are benign, but they occasionally convert to squamous cell skin cancer and must be surgically removed. The rate of transformation from actinic keratosis to skin cancer within one year is approximately 1 in 1000. People with sun-damaged skin should see a physician at regular intervals to check for skin cancer.
Causes
Risk Factors
The following factors increase your chances of developing actinic keratoses. If you have any of these risk factors, tell your doctor:
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Fair complexion
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Easy sunburning
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Cumulative exposure to sun
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Occupations or pastimes in sunlight (eg, farmer, lifeguard, outdoor sports)
Symptoms
If you have these lesions on your skin, do not assume they are actinic keratoses. These skin lesions may be cancer or another serious condition. If you find one of them, see your physician.
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Mottled red and white, thinning skin on sun-exposed areas
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Rough, scaly, or crusted patches on sun-exposed areas
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam. You may be referred to a dermatologist (a skin doctor).
Tests may include the following:
Treatment
Talk with your doctor about the best treatment plan for you. Treatment options include the following:
Surgical Removal
Individual lesions can be curetted (scraped with a circular cutting instrument under local anesthesia) or shaved with a scalpel. If there is a question of cancer, a biopsy specimen will be sent for microscopic examination.
Cryosurgery
Liquid nitrogen or a freeing spray kills the abnormal tissue, allowing normal healing to replace the lesion.
5-fluorouracil (5-FU) Cream
Applied twice a day for 2-4 weeks, 5-FU selectively attacks damaged skin so that normal skin can grow in its place. The result is temporary redness and rawness (like a bad sunburn), but the worse the reaction, the better the final result. This is the treatment of choice for badly sun-damaged skin with multiple actinic keratoses.
Chemical Peeling
Various acids can destroy superficial layers of skin, allowing normal skin to heal over the damage.
Photodynamic Therapy (PDT)
A chemical, 5-aminolevulinic acid, applied to the skin sensitizes the abnormal growths to light. If they are then exposed to strong light, the keratoses are destroyed.
Imiquimod
A topical cream that treats actinic keratosis by modulating a local immune response.
Diclofenac Gel
This is applied locally and is found to be helpful in treating actinic keratosis.
Prevention
To help reduce your chances of getting actinic keratoses and skin cancer, take the following steps:
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Avoid sun exposure.
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Wear long sleeves, long pants or a long skirt, and a wide-brimmed hat when outdoors, especially during the middle of the day.
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Use sun screen with an SPF of at least 15. Use of sunscreen was found to reduce the rate of actinic keratosis by 50%.
RESOURCES:
American Academy of Dermatology
http://www.aad.org
American Osteopathic College of Dermatology
http://www.aocd.org
CANADIAN RESOURCES:
BC Cancer Agency
http://www.bccancer.bc.ca
BC Health Guide
http://www.bchealthguide.org
References:
Actinic keratosis. DynaMed website. Available at: http://www.dynamicmedical.com/dynamed.nsf?opendatabase. Accessed August 11, 2005.
Actinic keratosis: what you should know about this common precancer. The Skin Cancer Foundation website. Available at: http://www.skincancer.org/ak/index.php. Accessed December 11, 2006.
Actinic keratosis: what you should know about this common precancer. The Skin Cancer Foundation website. Available at: http://www.skincancer.org/ak/index.php. Accessed August 11, 2005.
Chronic effects of sunlight. In: The Merck Manual, 17th ed. West Point, PA: Merck and Co.; 1999.
Jeffes EW III, Tang, EH. Actinic keratosis. Current treatment options. Am J Clin Dermatol. 2000;1:167.
Rivers JK, Arlette J, Shear N, et al. Topical treatment of actinic keratoses with 3.0% diclofenac in 2.5% hyaluronan gel. Br J Dermatol. 2002;146:94.
Stockfleth E, Meyer T, Benninghoff B, Christophers E. Successful treatment of actinic keratosis with imiquimod cream 5%: a report of six cases. Br J Dermatol. 2001;144:1050.
