Seborrheic keratosis (seb-o-REE-ik care-uh-TOE-sis) is a common skin growth. It may look worrisome, but it is benign (not cancer). These growths often appear in middle-aged and older adults. Some people get just one. It is, however, more common to have many. They are not contagious.
Most often seborrheic keratoses start as small, rough bumps. Then slowly they thicken and get a warty surface. They range in color from white to black. Most are tan or brown. They can appear almost anywhere on the skin.
Seborrheic keratoses can look like warts , moles, actinic keratoses, and skin cancer . They differ, though, from these other skin growths. Seborrheic keratoses have a waxy, “pasted-on-the-skin” look. Some look like a dab of warm, brown candle wax on the skin. Others may resemble a barnacle sticking to a ship.
Who gets seborrheic keratoses?
In most people, seborrheic keratoses first appear in middle age or later. People who are most likely to get these growths have family members with seborrheic keratoses.
Sometimes the growths appear during pregnancy or after estrogen replacement therapy. Children rarely have these growths.
What causes seborrheic keratoses?
The cause of seborrheic keratoses is unknown. We do know the following:
- Seborrheic keratoses seem to run in families. Some people seem to inherit a tendency to get many of these growths.
- Some studies suggest that sun exposure may play a role. But we know that these growths appear on skin that gets sun and skin that is always covered. So more research is needed.
- Seborrheic keratoses are not contagious. These growths may seem to multiply and spread to other parts of the body. The truth is, this does not happen.