Seborrheic Keratosis

A seborrheic keratosis (seb-o-REE-ik ker-uh-TOE-sis) is a common benign skin growth, similar to a mole. Most people will have at least one in their lifetime. They tend to appear in mid-adulthood and their frequency increases with age. They are harmless and don’t require treatment, but you can have them removed if they bother you.

Skin growths like seborrheic keratoses are sometimes also called epidermal tumors. That doesn’t mean they’re cancer, though. Technically, moles and warts are also epidermal tumors. That just means they are clusters of extra cells on the epiderma, the outer layer of the skin. They aren’t considered a risk factor for skin cancer.

What does seborrheic keratosis look like?

Seborrheic keratoses are roundish or oval-shaped patches on the skin with a “stuck on” appearance. They are sometimes described as waxy or scaly. They are raised above the skin and even when they are flat you can feel them with your finger. They are usually brown, but can also be black or tan, and less often, pink, yellow or white. They often appear in numbers.

Seborrheic keratoses are characterized by keratin on the surface — the same fibrous protein that fingernails, hooves, and horns are made of. This causes the textural details that often distinguish the growths. Sometimes it looks like small bubbles or cysts within the growth. Sometimes it looks scabby or wart-like. Sometimes it looks like the ridges and fissures in a brain.

Who gets seborrheic keratosis?

Anyone can get one, but most commonly:

• People who are 50 and older. They usually begin to appear in middle age, and rarely in younger people. About 30% of people have at least one by the age of 40, and about 75% by the age of 70.
• People with a family history of it. About half of all cases of multiple seborrheic keratoses occur in families, suggesting that the tendency to develop many of them may be inherited.
• Lighter-skinned people. Classic seborrheic keratosis as described here appears less frequently in darker-skinned people. However, a variant of seborrheic keratosis called dermatosis papulosa nigra is very common in darker-skinned people, including those of African, Asian and Hispanic descent.