It’s not uncommon to get a scaly or crusty spot on your skin. Maybe you think it’s a scab, and you might even pick it off. But if it comes back, don’t ignore it. It could be something called actinic keratosis (or solar keratosis), which, untreated, could turn into skin cancer. Joshua Tournas, MD, a dermatologist with Banner Health, explained more about this skin condition.
What is actinic keratosis (AK)?
Actinic keratoses are precancerous areas or lesions on your skin. They usually appear in places where you’ve had a lot of sun exposure over time. Having them on the head, neck, hands or arms is very common. People who don’t realize their hair is thinning often develop them on their balding scalp. Women sometimes get them in their part or at the hairline if they pull their hair back and don’t wear a hat or apply sunscreen up to the hairline. You can get one, a few or many of them.
What are the symptoms?
You’ll notice a scaly or crusty spot on your skin. They’re usually small—just a few millimeters in diameter—and sometimes, they are itchy. Left untreated, they can become painful. You might feel your clothing snag on them, which can be annoying. “You can catch your fingernail on them, and people are tempted to pick them off,” Dr. Tournas said. But the damage causing the scaling comes from deeper in your skin, so it will keep regenerating—the crusty spot is a byproduct of a deeper problem.
“AKs are a big part of dermatology, especially as people get older. An estimated 15% of all dermatology visits relate to AKs,” Dr. Tournas said. It can spread quickly and may be well established before you notice symptoms.
Anyone can get AKs, but they are more common in lighter-skinned people who have had a lot of sun damage in their lifetime. Dr. Tournas said that people who work outdoors, golfers, tennis players and swimmers often get them.
What are the risks of actinic keratosis?
Untreated, these skin growths can become squamous cell carcinoma, which is a type of skin cancer. “We try to find as many as we can before they progress,” Dr. Tournas said.
How can you prevent actinic keratosis?
Protecting your skin that is exposed to the sun can help prevent AKs. But they may develop after many years of sun exposure. Over time, the sun’s ultraviolet rays cause genetic mutations in your skin that trigger AKs. So, it’s always important to protect your skin, but if you’ve had a lot of sun exposure in the past, you may not be able to prevent AKs from forming.
“You can’t go back in time and prevent the damage that’s already happened. But you can prevent progression with good sun protection now,” Dr. Tournas said.
How is actinic keratosis diagnosed and treated?
AKs are common, and dermatologists can usually diagnose them with a physical exam. Sometimes, they will use magnification to get a closer look. “We look at them and feel for that roughness,” Dr. Tournas said. Rarely, if it’s hard to tell whether an AK has become cancerous, you might need a procedure called a biopsy, where your doctor cuts out a small area to examine under a microscope.
There are two types of treatment for actinic keratosis, spot treatment and field treatment.
Spot treatment is used if you have a small number of AKs. Your doctor can use cryotherapy to treat them. That’s when the lesion is sprayed with cold liquid nitrogen in a controlled way to freeze the area. “The freeze penetrates to the base layer that’s causing the problem. The area may blister, or it may just peel away,” Dr. Tournas said.
You may develop other AKs in the future, but if you don’t have many, this treatment should continue to work.
Field treatment is used when you have a lot of AKs. There are a few reasons why you might develop many AKs. Dr. Tournas said it’s common in bald or balding men who didn’t realize how thin their hair was getting for many years, so they didn’t protect their scalp with a hat or sunscreen: “They might have dozens of these lesions on their scalp. They start to grow into each other and become almost innumerable.”
In those cases, you can’t simply freeze the AKs—the area is too big to treat that way. So, you can apply a chemotherapy agent called five fluorouracil to the site to clear the lesion field. Or you can use Imiquimod cream that helps your body’s immune system take care of the AKs. “These treatments do similar things, with a different mechanism of action,” Dr. Tournas said.
After several weeks of treatment, you’ll get a red, rashy reaction and most of the AKs should resolve. “You may need to come back and freeze a couple, but you’ve smoothed everything out,” Dr. Tournas said.
An alternative type of field treatment is called photodynamic therapy treatment (PDT) or blue light treatment. With it, your doctor will apply aminolevulinic acid to the affected area, and you’ll wait for from 90 minutes (about one and a half hours) to several hours while your skin converts it to a substance that’s sensitive to light. Then the skin is exposed to a specific wavelength of light, usually blue light, which kills the abnormal skin cells. Your skin may seem sunburned or may peel afterward, but it usually heals in a couple of weeks. “Photodynamic therapy treatments can replace a long-term course of topical agents,” Dr. Tournas said.
You may need to repeat field treatments every year or every few years to lower the number of AKs and reduce the likelihood that they will progress to skin cancer.
The bottom line
Actinic keratosis is a precancerous skin condition that causes small scaly or crusty spots on your skin. “If you’re picking something off your skin and it doesn’t go away, it’s time to see somebody,” Dr. Tournas said. To connect with a doctor who can evaluate your skin and recommend any needed treatments, reach out to Banner Health.