What are seborrheic keratoses?

Seborrheic keratoses are a type of skin growth common in older adults with a waxy “stuck-on” look. They are not cancerous but can resemble moles, warts, or actinic keratoses, a type of pre-cancerous skin growth. They are not contagious and can appear nearly anywhere on the body. Most seborrheic keratoses are tan or brown, but they can range in color from black to white. They develop slowly, starting as small, rough bumps, then gradually thickening and develop a warty surface.


What are the causes of seborrheic keratoses?

Although some studies have suggested that sun exposure is a contributing factor, seborrheic keratoses also appear on skin that is not exposed to the sun. A tendency to develop seborrheic keratoses seems to have a genetic component as it often runs in families. In most people, these growths first appear in middle age or even later, but occasionally they appear during pregnancy or after hormone replacement therapy. They are rare in children.

What are the symptoms of seborrheic keratoses?

Seborrheic keratoses can develop almost anywhere on the body. They tend to develop slowly, starting as small brown patches, then over time thicken and develop a bumpy surface. They can be larger than a quarter or very tiny. They are not painful, but some people experience itching. If the seborrheic keratosis is easily irritated by clothing or shaving, or it if grows quickly, bleeds or turns color, please visit Dermatology of Seattle right away! These are all possible signs of skin cancer.

What is the treatment and diagnosis?

Although most seborrheic keratoses do not require medical care, they should be examined by a dermatologist to confirm the diagnosis. At Dermatology of Seattle, our dermatologists can diagnose seborrheic keratosis with a quick exam most of the time. However, if the growth resembles skin cancer, a biopsy may be necessary. The dermatologist will remove it with a scalpel and examine the cells under a microscope to be sure.

Seborrheic keratoses can also be removed using a small amount of liquid nitrogen to freeze the growth. Other removal options include using electrocautery or cutting off using a surgical knife. These methods do not require stitches and usually the growth will not return in that spot, although more may develop elsewhere on the body.