Overview

A seborrheic keratosis (seb-o-REE-ik ker-uh-TOE-sis) is a common noncancerous skin growth. People tend to get more of them as they get older.

Seborrheic keratoses are usually brown, black or light tan. The growths look waxy, scaly and slightly raised. They usually appear on the head, neck, chest or back.

Seborrheic keratoses are harmless and not contagious. They don't need treatment, but you may decide to have them removed if they become irritated by clothing or you don't like how they look.

Symptoms

A seborrheic keratosis usually looks like a waxy or wartlike growth. It typically appears on the face, chest, shoulders or back. You may develop a single growth, though multiple growths are more common.

A seborrheic keratosis:

  • Ranges in color from light tan to brown or black
  • Is round or oval shaped
  • Has a characteristic "pasted on" look
  • Is flat or slightly raised with a scaly surface
  • Ranges in size from very small to more than 1 inch (2.5 centimeters) across
  • May itch

When to see a doctor

See your doctor if:

  • Many growths develop over a short time.
  • The growths get irritated or bleed when your clothing rubs against them. You may want the growths removed.
  • You notice suspicious changes in your skin, such as sores or growths that grow rapidly, bleed and don't heal. These could be signs of skin cancer.

Causes

Doctors don't know exactly what causes seborrheic keratoses. The growths tend to run in some families, so genes may play a role.

Risk factors

You're generally more likely to develop seborrheic keratoses if you're over age 50. You're also more likely to have them if you have a family history of the condition.