Seborrheic Keratosis

Topic Overview

What are seborrheic keratoses?

Seborrheic keratoses (say "seh-buh-REE-ick kair-uh-TOH-seez") are skin growths that some people get as they age. They are benign, which means they are not a type of cancer. The way they look may bother you, but they aren't harmful.1

These skin growths often appear on the back or chest, but they can occur on any part of the body. They grow slowly, and they may appear as single growths or in groups.

Seborrheic keratoses don't spread from person to person. There is no known way to prevent them.

These skin growths are common in middle-aged people, but they can appear as early as the teen years.2 Some women get them during pregnancy or after taking estrogen. Children seldom have them.

What causes seborrheic keratoses?

Experts don't know what causes seborrheic keratoses. But research has found that:2

  • They tend to run in families.
  • They seem to be related to sun exposure.

What are the symptoms?

Seborrheic keratoses usually cause no symptoms. But they can itch, bleed easily, or become red and irritated when clothing rubs them.

How seborrheic keratoses look can vary widely. They:

  • Range in color from white to light tan to black. Most are brown. Some are multicolored.
  • Range in size from tiny to larger than about 1 in. (2.5 cm) in diameter.
  • Range in texture from waxy and smooth to velvety to dry, rough, and bumpy.

They also:

  • May have dry scale, which you can easily pick off, or have a surface that crumbles when picked.
  • Can be dome-shaped with tiny white or black "horns" growing from the surface.
  • Can occur as a cluster of growths.
  • Can look like skin tags (small, soft pieces of skin that stick out on a thin stem).
  • Can swell and turn red.
  • Slowly grow over time and seldom go away on their own.

These growths may be mistaken for warts, moles, skin tags, or skin cancer.

How are seborrheic keratoses diagnosed?

Your doctor will look at the skin growth. He or she may need to take a sample (biopsy) of the growth to rule out cancer if the growth:

  • Itches or bleeds.
  • Becomes inflamed and red.
  • Is dark brown to black.

How are they treated?

Seborrheic keratoses don't need to be treated. But if one bothers you or you don't like how it looks, your doctor can remove it. Your doctor may freeze it off, cut it out, or use a tool that burns it off.

Since these growths aren't harmful and don't have to be treated, your insurance company may not pay for having them removed.

Should you worry about seborrheic keratoses?

A diagnosed seborrheic keratosis is nothing to worry about. But if you are unsure what type of skin growth you have, see your doctor. It may be hard to tell whether the growth is a keratosis, a mole, a wart, or skin cancer.

If you have a dark skin growth or any growths that form quickly, call your doctor right away.

Frequently Asked Questions

Learning about seborrheic keratosis:

Being diagnosed:

Getting treatment:

Symptoms

Seborrheic keratoses are common skin growths that usually cause no symptoms. They are benign, which means they are not cancerous. But they can itch, bleed easily, or become red and irritated when clothing rubs them.

Seborrheic keratoses can grow on any part of the body in clusters or singly. They occur most commonly on the back or chest. They often look like they have been pasted onto the skin. They can be flat or raised and can vary in appearance. Seborrheic keratoses:

  • Range in color from white to light tan to black. Most are brown. Some are multicolored.
  • Range in size from tiny to larger than 3 cm (1.2 in.) in diameter.
  • Range in texture from waxy and smooth to velvety to dry, rough, and bumpy.
  • May have dry scale, which you can easily pick off.
  • Can have a surface that crumbles when picked.
  • Can be dome-shaped with tiny white or black "horns" growing from the surface.
  • Can be in a cluster of different-colored growths.
  • Can resemble skin tags (small, soft pieces of skin that stick out on a thin stem).
  • Can swell and turn red without apparent cause.
  • Slowly grow over time, and seldom go away on their own.

The tendency to have seborrheic keratoses that grow in clusters seems to run in families and may be passed down from parent to child. In rare cases, a sudden growth of many seborrheic keratoses is related to cancer elsewhere in the body.

Several other skin conditions, such as warts and skin cancer, can look like seborrheic keratosis.

Exams and Tests

Your doctor can diagnose most seborrheic keratoses by doing a visual exam. He or she will look for the common appearance of a rough and bumpy surface.3 You may need a skin biopsy to rule out cancer if you have growths that:

  • Itch or bleed.
  • Become inflamed and red.
  • Are dark brown to black.

Treatment Overview

Seborrheic keratoses do not require treatment because they are not cancerous or otherwise damaging to your health. But if a seborrheic keratosis causes pain and discomfort or causes you concern about how it looks, your doctor can remove it.

Your treatment choices are:

  • Cryotherapy, the use of extreme cold. It works well for flat or slightly raised growths, but it may not work well for thicker growths.
  • Curettage, in which your doctor uses a spoon-shaped instrument (curette) to remove the growth. Regrowth is common after curettage alone.
  • Electrocautery (or electrodesiccation), which sends a low-voltage electrical charge through the tip of a needle to burn off a growth. This treatment is sometimes combined with curettage.
  • Surgical excision, the removal of the growth with a scalpel after your doctor injects a local anesthetic.
  • Laser, an intense beam of light that burns and destroys the growth.

What To Think About

Your doctor can tell you which treatments are best for your seborrheic keratosis, based on its type, size, and location. Be aware that your health insurance may view seborrheic keratosis removal as an elective procedure.

After a seborrheic keratosis is removed, the wound may be painful for a few days. Your doctor will tell you how to care for the wound as it heals. You may need to clean the area regularly and apply antibiotic ointment to prevent infection.

Removal of seborrheic keratoses is usually done in a way to minimize scarring. Cryotherapy, electrocautery, or laser treatment may cause permanent lightening of darker skin. Factors that may slow healing include advanced age, sun damage, and tobacco smoking.

Home Treatment

If clothing and daily activities irritate a seborrheic keratosis, you can cover it with an adhesive bandage to prevent rubbing and bleeding.

If you have had a seborrheic keratosis removed, your doctor will tell you how to care for the wound as it heals. You may need to clean the area regularly and apply antibiotic ointment to prevent infection.

References

Citations

  1. Motley RJ (2006). Seborrheic keratosis. In MG Lebwohl et al., eds., Treatment of Skin Disease, 2nd ed., pp. 609–610. London: Mosby Elsevier.
  2. Thomas VC, et al. (2008). Seborrheic keratosis section of benign epithelial tumors, hamartomas, and hyperplasias. In K Wolff et al., eds., Fitzpatrick's Dermatology in General Medicine, 7th ed., vol. 1, pp. 1054–1056. New York: McGraw-Hill Medical.
  3. Habif TP (2004). Seborrheic keratoses. In TP Habif, ed., Clinical Dermatology: A Color Guide to Diagnosis and Therapy, 4th ed., pp. 698–705. Edinburgh: Mosby.

Other Works Consulted

  • Habif TP, et al. (2005). Seborrheic keratosis section of Benign skin tumors. In Skin Disease: Diagnosis and Treatment, 2nd ed., pp. 384–393. Philadelphia: Elsevier Mosby.

Credits

Author Bets Davis, MFA
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer Alexander H. Murray, MD, FRCPC - Dermatology
Last Updated February 26, 2009

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