Health Library Seborrheic KeratosisFrom Healthwise

What are seborrheic keratoses?

Seborrheic keratoses (say "seh-buh-REE-ick kair-uh-TOH-sus") are noncancerous (benign) skin growths that some people develop as they age. They often appear on the back or chest, but they can occur on any part of the body. Seborrheic keratoses grow slowly, in groups or singly. They are usually easy for a doctor to diagnose. You may not like how they look, but they aren't harmful.¹

How can I identify a seborrheic keratosis?

How seborrheic keratoses look can vary widely. They may be pale white to brown or black. The most common texture is rough, with a bumpy, grainy surface that crumbles easily.² But they also may be smooth and waxy. They usually look like they've been stuck onto the skin. Some are tiny, and others grow larger than 3 cm (1.2 in) in diameter.²

Seborrheic keratoses may be mistaken for warts, moles, skin tags, or skin cancer.

What causes seborrheic keratoses?

Doctors don't know what causes seborrheic keratoses. But research has found:³

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

They are not contagious, so you cannot spread them to someone else. There is no known way to prevent them.

Seborrheic keratoses are common in middle-aged people, but they can appear as early as the teen years.³ Some women notice that they get them during pregnancy or after taking estrogen. Children seldom have these skin growths.

Are there risks related to seborrheic keratoses?

A diagnosed seborrheic keratosis is nothing to worry about. But seborrheic keratoses sometimes are mistaken for cancerous (malignant) skin growths. Or cancerous growths may blend in with seborrheic keratoses. If you have a skin growth that appears to be a seborrheic keratosis, ask your doctor to examine it. If you have a dark skin growth or a group of growths that develop rapidly, make an appointment to have them checked now.

How is it treated?

Seborrheic keratoses do not need to be treated. But if a seborrheic keratosis is easily irritated or painful or if the way it looks bothers you, you can have it removed.

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.

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.² 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.

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.

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.

Organization

• Skin Cancer, Melanoma
• Skin Cancer, Nonmelanoma
• Skin Changes
• Warts and Plantar Warts

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. 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.
3. 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.

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.

Author:	Bets Davis, MFA	Last Updated: February 26, 2009
Medical Review:	Kathleen Romito, MD - Family Medicine Alexander H. Murray, MD, FRCPC - Dermatology
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