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Actinic Keratosis

What Is Actinic Keratosis?

If you’ve spent a lot of time outside under the sun, you’ll probably start to notice brown spots appearing on your hands and arms as you get older. Sometimes called sun spots or age spots, the correct term for this condition is actinic keratosis. The spots themselves are called actinic keratoses.

Actinic keratosis (AK) is a very common skin condition. It occurs when skin cells called keratinocytes start to grow abnormally, forming scaly discolored spots. The skin patches may be brown, tan, grey, or pink. They tend to appear on the parts of the body that get the most sun exposure such as the hands, arms, face, scalp, and neck.

AK may actually be in situ stage squamous cell carcinoma (SCC) lesions. “In situ” means the lesions are confined to one location and not invading other tissue. In most cases, AK lesions are relatively benign. However, each lesion has about a 10 percent chance of progressing into an invasive form of SCC. Because of this risk, the spots should be monitored regularly for any suspicious changes.

What Causes Actinic Keratosis?

Actinic keratosis is primarily caused by long-term exposure to sunlight. People with the highest risk of developing AK generally:

  • are over the age of 60
  • have fair skin and blue eyes with a tendency to sunburn easily
  • have a history of sunburns earlier in life
  • have high levels of sun exposure over their lifetimes
  • have the human papilloma virus (HPV)

Other people at high risk for AK include albinos and organ transplant recipients who are taking immunosuppressant drugs

What Are the Symptoms of Actinic Keratosis?

Actinic keratoses start out as thick, scaly, crusty skin patches. These patches are generally about the diameter of a pencil eraser. Over time, the lesions may disappear, remain the same, or develop into SCC. There is no way of predicting which lesions may turn cancerous. If you notice any of the following changes in an age spot, you should have it examined by a dermatologist:

  • hardening of the lesion
  • inflammation
  • rapid enlargement
  • bleeding
  • redness
  • ulceration

If there are cancerous changes, don’t panic. This type of skin cancer is relatively easy to diagnose and treat in its early stages. Squamous cell skin cancer is the second most common type of human cancer. Over 250,000 new cases are diagnosed each year in the United States.

How Is Actinic Keratosis Diagnosed?

Most actinic keratoses can be diagnosed by eye. Your dermatologist may want to take a skin biopsy of any lesions that look suspicious. The only sure way to tell if an AK has changed into squamous cell carcinoma is with a skin biopsy.

What Kinds of Treatment are Available for Actinic Keratosis?

There are six main strategies for treating actinic keratoses.

  • Excision. Excision means cutting the lesion from the skin. The doctor may choose to remove extra tissue under and around the lesion if there are concerns about skin cancer. Depending on the size of the incision, stitches may or may not be needed. 
  • Cauterization. The affected lesions are burned with electric current. This kills the cells. 
  • Cryotherapy. The lesion is sprayed with a cryosurgery solution. It freezes the cells on contact. This kills them. The lesion then scabs over and drops off in a few days.
  • Chemical peels. Topical treatments such as5-fluorouracil kill the skin cells and cause the lesion to scab over and drop off. This treatment may be temporarily disfiguring. Be sure to ask your doctor about side effects of chemical peels, and what to expect after treatment.
  • Phototherapy. A solution is applied to the lesion and the affected skin is then exposed to a special light. The solution reacts to the light and causes the targeted cells to die. Common solutions used in phototherapy include prescription medications like aminolevulinic acid (such as Levulan Kerastick) and methyl aminolevulinate cream (Metvixia).
  • Immunotherapy. Imiquimod is a topical cream that is applied to the actinic keratoses several times a week. It increases the activity of the body’s immune system. It is not clearly understood exactly how Imiquimod works on actinic keratoses.

Ongoing Care and Prevention

Reducing exposure to sunlight is the best way to prevent new actinic keratoses. It also minimizes the risk of skin cancer. Remember to:

  • Always use sunscreen and wear long-sleeve shirts and hats in bright sunlight.
  • Avoid going outside at midday when the sun is brightest.
  • Use sunscreens with an (SPF) rating of at least 15. They should block both UVA and UVB light.
  • Use sunscreen year round and avoid tanning beds.

If you have AK, you should see a dermatologist regularly. They can monitor your skin for signs of SSC. When caught early, SSC is very treatable. So don’t put off seeing your dermatologist if you have any worrisome spots!

Content licensed from:

Written by: Janet Barwell and Elizabeth Boskey, PhD
Published on: Jul 16, 2012
Medically reviewed on: Sep 07, 2017: Justin Choi, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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