A seborrheic keratosis is a common, harmless growth on your skin. Doctors call it “benign,” which means it isn't a sign of cancer. Like moles, a seborrheic keratosis happens when extra skin cells bunch up together on the top layer of skin. Unlike a mole, it won't become cancerous. It can appear later in life, after about age 40. It’s most likely to happen on your face, scalp, chest, shoulders, belly, or back. It can show up anywhere except your palms and soles.
Often, your doctor can tell what a seborrheic keratosis is just by looking at it. If you’re worried that it could be cancer, or your doctor isn’t sure, they’ll do a biopsy to remove the growth and study it more closely.
What Does It Look and Feel Like?
Normally, it has a round or oval shape. It ranges from light tan to black in color. At first it looks and feels soft and smooth, like velvet. It might be about the size of a dime.
Over time, a seborrheic keratosis becomes scaly and thick, like melted candle wax that’s stuck to your skin. It can grow to be as large as a half-dollar coin.
It’s not painful. It can feel greasy, rough, or soft when you touch it.
It might itch. Sometimes it can rub against your clothes and get in the way of shaving and other things you do. Even though it can be annoying, it’s important not to scratch, pick, or rub the area. That can cause it to swell, bleed, or get infected.
What Are the Causes?
Doctors aren’t sure what causes seborrheic keratoses. So there’s no real way to prevent them.
The condition tends to run in families. It almost always happens later in life, especially after age 50. You're more likely to have one if other people in your family have it too. It's most common in people with light skin. It can appear during pregnancy, or if you’ve had hormone replacement therapy.
Some studies show sunlight might play a part. But these growths can show up with or without exposure to the sun, so we need more research to know exactly why they form.
They aren’t contagious. If you have one, it won’t spread to other people or to other parts of your body, though it is common to have not just one, but many. They usually don’t go away on their own.
When Should I See My Doctor?
Most of the time, a seborrheic keratosis won’t cause problems. But make an appointment if you notice any of the following:
- It bothers you a lot, or becomes irritated or inflamed.
- You notice lots of growths at once. Normally, they appear one or two at a time and increase in number.
- It seems to change, or grow quickly.
- It bleeds and doesn’t heal.
If any of these things happen, or if you just don’t like how a growth looks or feels on your skin, you can have it removed.
What’s Removal Like?
Start with your main doctor. They might refer you to a dermatologist – a skin specialist.
They’ll choose one of the following, simple ways to remove the growth, usually in their office or clinic.
- Burning. This uses an electric current to burn away the seborrheic keratosis. It can take longer than other ways.
- Freezing. Doctors called this “cryosurgery.” It uses super-cold liquid nitrogen to remove the growth. It might require several treatments if it’s very large or thick.
- Laser. A harmless beam destroys the physical structure of the area.
- Scraping. The doctor uses a special tool to raze it off. This is often done along with freezing or burning.
Most seborrheic keratoses don’t return after they’re removed. But a new one can still appear somewhere else on your body.
Sometimes removing one can make your skin a little lighter at that spot. It usually blends in better over time, but not always.
Do Self-Tanners Affect It?
It’s normal for seborrheic keratoses to grow darker over time. But if you use an artificial tanning product that contains DHA, an omega-3 acid, it can change the color of the growths as well as the skin around them.
Some people who’ve used these products have seen seborrheic keratoses grow darker quickly. That’s because the skin absorbs the artificial tan pigments. Doctors have found that this kind of color change isn’t a sign of cancer.