Actinic Keratosis

Actinic keratosis is a common precancerous skin condition

man who has undergone photo dynamic therapy on face
Photo Dynamic Therapy is a method used in dermatology to repair skin that has been damaged by over exposure to sunshine. Charles Bowman/Photolibrary/Getty Images

Actinic keratosis (AK) (also called solar keratosis or sun spots ) is a common precancerous skin condition caused by excessive exposure to ultraviolet light.

What is Skin Cancer?

Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun. But this common form of cancer can also occur on areas of your skin not ordinarily exposed to sunlight.

There are three major types of skin cancer — basal cell carcinoma, squamous cell carcinoma and melanoma.

Causes of Skin Cancer

Skin cancer begins in your skin's top layer — the epidermis. The epidermis is a thin layer that provides a protective cover of skin cells that your body continually sheds. The epidermis contains three main types of cells:

  • Squamous cells lie just below the outer surface and function as the skin's inner lining.
  • Basal cells, which produce new skin cells, sit beneath the squamous cells.
  • Melanocytes — which produce melanin, the pigment that gives skin its normal color — are located in the lower part of your epidermis. Melanocytes produce more melanin when you're in the sun to help protect the deeper layers of your skin.

Where your skin cancer begins determines its type and your treatment options.

Much of the damage to DNA in skin cells results from ultraviolet (UV) radiation found in sunlight and in the lights used in tanning beds. But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight.

This indicates that other factors may contribute to your risk of skin cancer, such as being exposed to toxic substances or having a condition that weakens your immune system.

Actinic Keratosis

AKs are rough, dry, tan- or pink-colored blemishes that often appear on facial skin -- near the eyes, on the nose, on the ears, or the lips -- or other parts of the body that receive intense sunlight, such as the back of the hands.

They are most common in fair-skinned, middle-aged or elderly individuals, who may have a single lesion or many.

Actinic keratosis can lead to more serious invasive squamous cell carcinoma (SCC) if left untreated. It is estimated that 20 to 40 percent of SCCs begin as actinic keratosis. In fact, some doctors believe that AK is actually an early stage of squamous cell carcinoma. Treatments include cryosurgery (freezing), surgical excision (removal), curettage (scraping), photodynamic therapy or topical (skin-only) creams such as fluorouracil, diclofenac, and imiquimod. The choice of treatment depends on the location of the lesion, how many there are, and the choice of the patient.

A gallery of photographs of actinic keratosis is available to help you identify them.


Mayo Clinic. Skin Cancer.

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