Medical Definition of actinic keratosis
: a rough, scaly, pink or white growth that occurs on the surface of the skin in areas (such as the face, neck, and back of the hands) frequently exposed to sunlight and that may develop into squamous cell carcinoma Excessive exposure to sunlight causes skin cancer, but a precancerous lesion called an actinic keratosis appears long before the cancer.— Gabe Mirkin, The Chicago Tribune, 7 July 1994
Note: Actinic keratosis is caused by sun-induced damage to the DNA of keratinocytes in the skin. People with blond or red hair and fair skin are more susceptible to actinic keratosis.
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