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Actinic (solar) keratosis
What is actinic keratosis?
Actinic keratosis (AK), also known as solar keratosis, is a precancer caused by exposure to sun and ultraviolet light. It is a scaly, rough, or bumpy spot on the skin. Sometimes it is easier to feel it with a fingertip than to see it. The most common areas that actinic keratoses appear are on: the face, lower lip, bald scalp, ears, backs of the forearms and hands, shins and backs of the feet.
Actinic keratosis is most common in older Caucasian people, but recently we have started seeing them in younger people as well, including people in their 20s – likely due to tanning.
How can I recognize actinic keratosis on my skin?
Actinic keratosis is usually a rough, scaly, sandpaper–like spot on the skin that does not want to go away. Sometimes may look like red of light-brown spot without any roughness. It may be somewhat tender and feel sore, but it can be without any abnormal sensation.
What should I do if I think I have one?
You should see your health care provider since actinic keratosis can turn into a form of skin cancer called “squamous cell carcinoma.” This can happen in small percentage of actinic keratoses (up to 10%), but since no one can predict which one will turn into cancer your healthcare provider will probably treat it.
How will my health care provider determine that I have actinic keratosis?
Usually good physical exam with touching the skin and looking at it with special instrument called dermatoscope will be enough. Dermatoscope is a handheld instrument that looks similar to battery lamp, but with special system of polarized lenses and LED light that enables your healthcare provider to take deeper look into the skin. It is usually used by dermatologists. Another name for dermatoscope is epiluminescence microscope.
However, even the most experienced health care provider sometimes may not be sure whether the skin changes are due to actinic keratosis. In that case the best would be that you have a test called a skin biopsy.
What is a skin biopsy?
A skin biopsy is a cutting a small sample of the changing skin off to be looked under microscope. There are two types of biopsies, both performed under the local anesthesia and both taking about 5 -10 minutes to perform – a biopsy and a punch biopsy.
Shave biopsy is the most common type since it is usually preferred both by patients and by their health care providers, since it does not require placement of stitches and is faster. Your health care provider will numb the skin with small amount of fast acting local anesthetic and then use a razor blade or a more sophisticated instrument called a Dermablade (our favorite), which is actually a razor blade with handles that enable your healthcare provider to have a better control over the depth of the biopsy. Afterwards, the bleeding is stopped by using special liquid called aluminum chloride (which is, by the way, the active ingredient in many anti-sweating deodorants). Then plain Vaseline or a double antibiotic ointment and bandage are placed on the biopsy wound.
Punch biopsy is also a very fast procedure, where your health care provider will numb the skin with small amount of fast acting local anesthetic and then sterilize the skin using special cleansing swabs soaked with povidone-iodine, or chlorhexidine gluconate, put sterile drape over the area, and then use a pen-like cylindrical instrument called a punch, which looks like a very small cookie-cutter that would produce small cylindrical specimen with diameter of about 4 mm and depth of about 5-8 mm. We usually close the wound and stop the bleeding by placing a nylon stitch that should be removed in 1-2 weeks. Then plain Vaseline or a double antibiotic ointment and bandage are placed on the biopsy wound.
The results of the skin biopsy are usually available within 1-2 weeks. We always call our patients with all the results. Please, never agree to a policy of “no news is good news”, since results may be misplaced with possible bad outcome to your health.
What is the treatment of actinic keratosis?
Since up to 10% of actinic keratoses can turn into skin cancer called squamous cell carcinoma and since no one can predict which actinic keratosis will turn into cancer, your healthcare provider will probably treat it.
Usual treatment is called cryotherapy, or freezing using liquid nitrogen, which is suitable for relatively limited number of spots. When the involved area of skin is larger and with many spots, your health care provider may use so-called “field therapy” by prescribing creams that would clear most of the actinic keratoses. These creams are imiquimod (brand names: Aldara, Zyclara), 5-florouracil (brand names: Efudex, Carac), or ingenol mebutate (brand name: Picato). Another form of “field therapy” is a controlled burn of the involved area by using a special light also known as photodynamic therapy (brand name of the procedure: Blu-U). If the spot is larger and harder, then your health care provider may decide to do a curettage (i.e. scraping the spot off with a sharp instrument called curette) under local anesthesia.
How often should I see my health care provider after first treatment?
Since average treatment success is about 60-80% you should see your health care provider again within 3 months for a check-up. However, go and see your health care provider earlier if the treated spots get bigger, or if you develop more spots.
How do I prevent actinic keratosis? The best way is to follow the advice below, and not to tan. Any tan color of skin after exposure to sun or ultraviolet light is a sign of genetic damage to your skin.
● Seek shade and stay out of the sun in the middle of the day (from 10 a.m. to 5 p.m.). We teach our kids when playing outside to follow the shade of our home.
● Wear a wide-brimmed hat, long-sleeved loose-fitting shirt, long loose-fitting pants, or long skirt outside.
● Put on sunscreen with at least Sun Protection Factor (SPF) of 30. Look for sunscreens with titanium dioxide and zinc oxide. My family’s favorite is Banana Boat KIDS with SPF 50 that contains both titanium dioxide and zinc oxide, and is currently one of the cheapest sunscreens.
● Do not use tanning beds.
Worth of mentioning is an iconic Slip-Slop-Slap sun protection campaign in Australia during the 1980s.
It stands for:
Slip on a shirt,
Slop on the 30+ sunscreen,
Slap on a hat