Skin Lesions (Actinic Keratosis)

Actinic keratoses (AKs) are common skin lesions.  Caused by years of sun exposure, AKs also are called “solar keratoses” or “sun spots,” Fair-skinned people are more susceptible, and AKs tend to appear on skin that receives the most sun.  The forehead, ears, neck, arms, hands, lower lip, a bald scalp, and lower legs of women are common sites.  No matter where AKs develop, they are considered the earliest stage in the development of skin cancer.

Like skin cancer, AKs develop when ultraviolet (UV) light from the sun damages cells in the skin.  When AKs form, the affected skin cells are the keratinocytes. These tough-walled cells make up 90 percent of the epidermis (the outermost layer of skin) and give the skin its texture. Changes to these cells cause the skin to become rough and scaly.  Bumps or small horn-like growths form.  If the cells continue to change, AKs can progress to squamous cell carcinoma, a type of skin cancer. 

The typical actinic keratosis (AK) is a dry, scaly, rough bump that is skin-colored to reddish brown. The lesion may range from the size of a pinhead to larger than a quarter. Some skin colored AKs may be easier to feel than see.  When touched, these often feel like sandpaper.

Sometimes an AK grows rapidly upward, causing it to resemble the horn of an animal.  When this happens, the AK is called a “cutaneous horn.”  Horns vary in size from that of a pinhead to a pencil eraser.  Some horns grow straight; others curve.  Cutaneous horns often form on the ears, which tend to receive years of sun exposure.

AKs also commonly form on the lower lip.  An AK on the lower lip is known as “actinic cheilitis” and looks like a diffuse, scaly patch on a dry, often cracked lip.

No matter where an AK forms, it can seem to disappear for weeks or months and then return.  This also can happen when an AK is scraped off.  The damaged cells continue to grow, and the AK returns.  A dermatologist can determine when to treat AKs and how.

When treating AKs, dermatologists may use one therapy or combine therapies.  Some available treatments for actinic keratoses are:

CRYOSURGERY The most common treatment for AKs, cryosurgery involves applying a cryogenic (extremely cold) substance, usually liquid nitrogen, to the lesion.  This freezes the surface skin, causing the skin to flake off.  New skin forms.  The main side effect is skin redness; blistering may occur.

TOPICAL CHEMOTHERAPY To destroy AKs, patients apply a cancer fighting cream or lotion (e.g., 5-fluoruracil,) to their skin.  Red spots may remain on the treated skin for a while.  Another treatment option such as cryosurgery may be necessary to treat thicker lesions that a cream or lotion cannot fully penetrate.

 TOPICAL IMMUNOTHERAPY When applied to the skin, this medication (e.g., imiquimod) stimulates the patient’s own immune system to destroy the AKs and accompanying damaged skin cells.  Patients apply this medication at home as directed by their dermatologist.

TOPICAL NSAID (NON-STEROIDAL ANTI-INFLAMMATORY DRUG) Patients apply this medication (e.g., sodium diclofenac gel) to the lesions as directed. During treatment, patients should avoid the sun.  The medication works to destroy the AKs and accompanying solar damage.

PHOTODYNAMIC THERAPY A solution that makes the skin more sensitive to light is applied and left on the skin.  After a few hours, the treated skin is exposed to “blue” or “red” light, which activates the solution and destroys the AKs.  Areas of redness may develop in treated regions. These will fade after several days.

CHEMICAL PEELING A chemical solution is applied to the skin in order to peel away the AKs and damaged skin.  As the treated skin peels off, new healthy skin replaces it.  It is common to experience discomfort, redness, and crusting in the treated areas.

LASER SKIN RESURFACING A laser may be used to remove AKs and damaged skin.  A common side effect is redness immediately afterward.  It may take a week or two for the skin to heal.

Research and development of other treatments for AKs is ongoing. No one therapy works on all AKs or in all individuals.

This should start early in life.  Sun damage begins in childhood and puts the child at risk for AKs and skin cancer later in life. However, it is never too late to prevent new AKs – even in adults who have AKs.


-Seek shade when appropriate, remembering that the sun’s rays are strongest between 10 a.m. and 4 p.m.  If your shadow is shorter than you are, seek shade.

-Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses, where possible.

– Generously apply sunscreen daily.  Sunscreen should have a sun protection factor (SPF) of 15 or higher and offer broad-spectrum protection (both UVA and UVB protection). Sunscreen should be applied at least 20 minutes before going outdoors to all skin that will be exposed such as the face, ears, and hands.

– Reapply sunscreen every 2 hours, after swimming or sweating, even on cloudy days