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 aren't a type of cancer. The way they look may bother you, but they aren't harmful.

These skin growths often appear on the back or chest, but they can occur on any part of the body. They grow slowly and seldom go away on their own.

These skin growths are common in middle-aged and older people, but they can appear as early as the teenage years. 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:

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

What are the symptoms?

Seborrheic keratoses can itch, bleed easily, or become red and irritated when clothing rubs them.

How the growths look can vary widely. They:

• 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.
• Range in colour from white to light tan to black. Most are brown. Some are multicoloured.

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 single growth or 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.

These growths may be mistaken for warts, moles, skin tags, or melanoma (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 if it's not clear what the growth is or if it:

• 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 (cryotherapy).
• Cut it out (curettage or excision).
• Use a tool that burns it off (electrocautery or laser treatment).

Should you worry about seborrheic keratoses?

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 your doctor says your skin growth is a seborrheic keratosis, you usually don't need to worry about it. But if it is growing fast, looks unusual, or is bleeding or causing pain, see your doctor. You may be referred to a dermatologist.