Seborrheic keratoses

  • Overview
    Seborrheic keratosis: This non-cancerous growth can grow quite thick and have a warty surface.

    Seborrheic keratoses: Overview

    Seborrheic keratosis (seb-o-REE-ik care-uh-TOE-sis) is a common skin growth. It may look worrisome, but it is benign (not cancer). These growths often appear in middle-aged and older adults. Some people get just one. It is, however, more common to have many. They are not contagious.

    Most often seborrheic keratoses start as small, rough bumps. Then slowly they thicken and get a warty surface. They range in color from white to black. Most are tan or brown.

    They can appear almost anywhere on the skin.

    Seborrheic keratoses can look like warts, moles, actinic keratoses, and skin cancer. They differ, though, from these other skin growths. Seborrheic keratoses have a waxy, “pasted-on-the-skin” look. Some look like a dab of warm, brown candle wax on the skin. Others may resemble a barnacle sticking to a ship.

    Image used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.

    Seborrheic keratosis
  • Symptoms
    Seborrheic keratoses: Seborrheic keratoses can look like stucco splattered on the skin.

    Seborrheic keratoses: Signs and symptoms

    Seborrheic keratoses tend to:

    • Start as small, rough bumps, then slowly thicken and develop a warty surface.
    • Have a waxy, stuck-on-the-skin look.
    • Be brown, though they range in color from white to black.
    • Range in size from a fraction of an inch to larger than a half-dollar.
    • Form on the chest, back, stomach, scalp, face, neck, or other parts of the body (but not on the palms and soles).
    • Cause no pain — some itch.
    Seborrheic keratoses: Like his father, this man developed many of these growths on his skin.

    Images used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.





    Seborrheic keratosis

  • Causes

    Seborrheic keratoses: Who gets and causes

    Who gets seborrheic keratoses?

    The people most likely to develop these harmless growths have fair skin and family members who have seborrheic keratoses. These growths also develop in people with medium to dark skin. In dark skin, seborrheic keratoses tend to be small and appear around the eyes.

    Some people develop seborrheic keratoses during pregnancy or after estrogen replacement therapy.

    Most people develop seborrheic keratoses in middle age or later. The number of seborrheic keratoses tends to increase with age.

    Children rarely have seborrheic keratoses.

    What causes seborrheic keratoses?

    The cause of seborrheic keratoses is unknown. We do know the following:

    • Seborrheic keratoses seem to run in families. Some people seem to inherit a tendency to get many of these growths.

    • The sun may play a role in causing seborrheic keratoses. Studies suggest that these growths develop on skin that's gotten lots of sun. Because these growths also develop on skin that's always covered, more research is needed.

    • Seborrheic keratoses are not contagious. These growths may seem to multiply and spread to other parts of the body. What's really happening is that people get more of these growths as they age.

    Seborrheic keratosis
  • Treatment

    Seborrheic keratoses: Diagnosis and treatment

    How do dermatologists diagnose seborrheic keratoses?

    In most cases, a dermatologist can tell if your skin growth is a seborrheic keratosis by looking at it. Sometimes, a seborrheic keratosis can look like a skin cancer. If it does, the dermatologist will remove the growth so that it can be looked at under a microscope. This is the only way to tell for sure whether a growth is skin cancer.

    How do dermatologists treat seborrheic keratoses?

    Because seborrheic keratoses are harmless, they most often do not need treatment. A dermatologist may remove a seborrheic keratosis when it is:

    • Looks like a skin cancer
    • Gets caught on clothing or jewelry
    • Becomes irritated easily
    • Seems unsightly to a patient

    If the growth looks like skin cancer, your dermatologist will likely shave off the growth with a blade or scrape it off. This will allow a specially trained doctor to look for skin cancer cells under a microscope.

    Other treatments for seborrheic keratoses include:

    • Cryosurgery: The dermatologist applies liquid nitrogen, a very cold liquid, to the growth with a cotton swab or spray gun. This destroys the growth. The seborrheic keratosis tends to fall off within days. Sometimes a blister forms under the seborrheic keratosis and dries into a scab-like crust. The crust will fall off.

    • Electrosurgery and curettage: Electrosurgery (electrocautery) involves numbing the growth with an anesthetic and using an electric current to destroy the growth. A scoop-shaped surgical instrument, a curette, is used to scrape off the treated growth. This is the curettage. The patient does not need stitches. There may be a small amount of bleeding. Sometimes the patient needs only electrosurgery or just curettage.


    After removal of a seborrheic keratosis, the skin may be lighter than the surrounding skin. This usually fades with time. Sometimes it is permanent. Most removed seborrheic keratoses do not return. But a new one may occur elsewhere.

    Seborrheic keratosis

  • Tips

    Seborrheic keratoses: Tips for managing

    Most seborrheic keratoses do not require treatment. You should see a dermatologist if the growth:

    • Grows quickly, turns black, itches, or bleeds (possible signs of skin cancer).
    • Appears suddenly, along with many other new skin growths (possible sign of cancer inside the body).
    • Differs from what a typical seborrheic keratosis looks like.
    • Looks dry, flat, rough, and scaly (it could be an actinic keratosis, which can progress to a type of skin cancer).
    • Becomes easily irritated, such as from shaving or clothes rubbing against it.
    • Displeases you and you want it removed.

    Do not try to remove a seborrheic keratosis yourself. There is a risk of infection.

    Seborrheic keratosis