What Is Actinic Keratosis?

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What Is It?

An actinic keratosis, also known as a solar keratosis, is a scaly or crusty growth (lesion). It most often appears on the bald scalp, face, ears, lips, backs of the hands and forearms, shoulders, neck or any other areas of the body frequently exposed to the sun. You’ll often see the plural, “keratoses,” because there is seldom just one.

In the beginning, actinic keratoses are frequently so small that they are recognized by touch rather than sight. It feels as if you were running a finger over sandpaper. Patients may have many times more invisible (subclincal) lesions than those appearing on the surface.

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

  • Actinic keratosis on the back of the hand. These precancers commonly occur on the face and the back of the hands.

  • Closeup shows elevation, roughness, and crusting. Some keratoses, like this one, are quite discrete and difficult to distinguish clinically from squamous cell carcinoma.

  • Photos courtesy of:
    Pearon G. Lang, Jr., MD, and
    Memorial Sloan Kettering Cancer Center
    Deptartment of Dermatology

Is There Cause for Concern?

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.

Another form of actinic keratosis, actinic cheilitis, develops on the lips and may evolve into squamous cell carcinoma.

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.