Seborrheic keratoses are benign (noncancerous) skin growths that develop from skin cells called keratinocytes. These growths have a waxy or greasy look and can be tan, brown or black. They look like they have been glued or stuck onto the skin. Over time, the growths become rough and crusty looking.

They are usually found on the chest and back but can appear anywhere on the body, including the face, scalp and neck. No one knows what causes seborrheic keratoses, but they become more common with age. Most people will develop some as they get older, and children rarely have them.

Seborrheic keratoses tend to have a greasy appearance and look as though they were glued onto the skin, as opposed to growing from it. They may be tiny, or larger than 3 inches across. They rarely itch. They are not contagious and there is no way to prevent them from developing. Importantly, they do not go away on their own. If they are not removed, they will last a lifetime.

Physicians usually can diagnose seborrheic keratoses by looking at them. In rare cases, they may look like other skin disorders, including malignant melanoma. If the diagnosis is uncertain, your physician may want to do a biopsy, in which case a portion of the growth is removed and examined under a microscope.

Seborrheic keratoses do not require treatment. Although they may grow relatively large and can become dark, they are not dangerous. If they become irritated, itchy or unsightly or if they bleed, they can be removed in a doctor’s office. Treatment is mostly painless. The three main methods of removal are:

  • Curettage -After the skin is numbed, the growths are sliced or scraped off using an instrument called a curette.
  • Cryosurgery or freezing – Liquid nitrogen is applied to the growths. The growths crust over and then fall off a few weeks later.
  • Electrosurgery – An electric current burns the growths off.

Schedule an appointment if you develop any unusual skin growths, if existing growths start to change their appearance, or if multiple seborrheic keratoses develop suddenly. It may be a sign of another disease.

Remember, seborrheic keratoses do not go away on their own, but they can be removed if they become irritating or unsightly. There is no harm in not treating the growths, because they are benign (noncancerous) and do not become cancerous.