Actinic Keratosis
Actinic Keratosis and Precancerous growths:
The term "precancerous" is used because these abnormal areas of skin are more likely to turn malignant than 
healthy skin. Precancerous growths (lesions) are visible to the naked eye, and they look different from normal cells when examined under a microscope. They are important to recognize, because they are a warning sign of potential skin cancer.
Actinic keratoses (AKs) are rough, dry and scaly patches of skin that develop on the outermost layer of the skin after years of exposure to ultraviolet (UV) rays of the sun. Often they feel like sandpaper or crusts of dry skin. These lesions typically range in color from skin-toned to reddish brown and in size from that of a pinhead to larger than a quarter. Occasionally, a lesion has a rapid upward growth and resembles an animal horn and is called a “cutaneous horn.”
A dermatologist should evaluate anyone who is suspicious that may have developed AKs. These lesions are considered to be the earliest stage in the development of skin cancer and can progress to squamous cell carcinoma, a type of skin cancer that can be fatal. Having AKs makes one more susceptible to other forms of skin cancer, including melanoma. Melanoma is considered the most lethal form of skin cancer because it can rapidly spread to the lymph system and internal organs.
AKs are most likely to appear on the face, lips, ears, scalp, neck, backs of the hands and forearms, shoulders and back — the parts of the body most often exposed to sunshine.
AKs usually appear after age 40 because they take years to develop. However, even teens can have AKs when they live in areas that receive high-intensity sunlight year round, such as Florida and Southern California.
Millions of Americans have AKs, and the number continues to grow. In fact, AKs are so common today that treatment for these lesions ranks as one of the most frequent reasons people consult a dermatologist.
