Actinic keratosis (AK) or solar keratoses are scaly, crusty growths (lesions) caused by damage from the sun’s ultraviolet (UV) rays.

 

You’ll often see the plural, “keratoses,” because they seldom come as one.

 

They typically appear on sun-exposed areas such as the face, bald scalp, lips, and the back of the hands, and are often elevated, rough in texture, and resemble warts. Most often, actinic keratoses develop slowly and reach a size from an eighth to a quarter of an inch. Early on, they may disappear only to reappear later. Most become red, but some will be light or dark tan, pink, red, a combination of these, or the same color as your skin. Occasionally they itch or produce a pricking or tender sensation. They can also become inflamed and surrounded by redness. In rare instances, actinic keratoses can even bleed. If left untreated, up to ten percent of AKs develop into squamous cell carcinoma (SCC), the second most common form of skin cancer. In rarer instances, AKs may also turn into basal cell carcinomas, the most common form of skin cancer.

 

In the beginning, actinic keratoses are often very small and only recognized by touch rather than sight. It feels as if you are running a finger over sandpaper. Patients may have many more invisible (subclinical) lesions than those appearing on the surface.

If you have actinic keratoses, it indicates that you have sustained sun damage which could develop in any kind of skin cancer – not just squamous cell carcinoma.

 

Although the vast majority of actinic keratoses remain benign, some studies report that up to ten percent may advance to squamous cell carcinoma. This percentage does not sound very large, but it has a large impact. When it comes to squamous cell carcinomas, 40-60 percent begin as untreated actinic keratoses and may advance to invade the surrounding tissues. About 2 to 10 percent of these squamous cell carcinomas spread to the internal organs and are life-threatening.

 

The more keratoses you have, the greater the chance that one or more may turn into skin cancer. In fact, some scientists interpret actinic keratosis as the earliest form of squamous cell carcinoma.

 

Examine your skin regularly for lesions. But it’s not always that simple: many actinic keratoses have quite a different appearance, so if you find any unusual or changing growth, be suspicious and see your doctor promptly.