What Is a Seborrheic Keratosis?

A seborrheic keratosis is a common, harmless growth on your skin. Doctors call it “benign,” which means it doesn’t cause cancer. It can appear later in life, after about age 40. It’s most likely to happen on your face, scalp, chest, shoulders, or back. But it can show up anywhere.

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, she’ll 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. It’s important not to scratch, pick, or rub the area.

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 can appear during pregnancy, or if you’ve had hormone replacement therapy.

Some studies show sunlight might play a part. But more research needs to be done since the growths show up with or without exposure to the sun.

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.

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What’s Removal Like?

Start with your main doctor. She might refer you to a dermatologist -- a skin specialist.

She’ll choose one of the following, simple ways to remove the growth, usually in her 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.

WebMD Medical Reference Reviewed by Stephanie S. Gardner, MD on March 06, 2019

Sources

SOURCES:

American Academy of Dermatology: “Seborrheic Keratoses: Who Gets and Causes.”

Mayo Clinic: “Seborhheic Keratosis.”

Medscape: “Seborrheic Keratosis Clinical Presentation.”

National Institutes of Health: “Does It Look Like Melanoma? A pilot study of the effect of sunless tanning on dermoscopy of pigmented skin lesions.”

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