What is seborrheic keratosis?

Date: Sep-28-2013Seborrheic keratosis is a very common harmless, usually pigmented, noncancerous growth on the skin. It usually appears as a pale, black or brown growth on the back, shoulders chest or face, but can appear anywhere on the skin.

The plural of keratosis is keratoses. Seborrheic keratoses are also known as basal cell papillomas or seborrheic warts.

The American Academy of Dermatology says that although seborrheic keratosis may look worrisome, it is benign - not a cancer.

They tend to appear from middle-age onwards. Some individuals may have just one, however, most people who have them have several.

Seborrheic keratosis is not contagious.

Note on spelling: USA/Canada - seborrheic. UK, Ireland, Australasia - seborrhoeic.
What are the signs and symptoms of seborrheic keratosis?

Seborrheic keratoses may look like:

warts
moles
skin cancer
actinic keratoses - a rough, scaly patch that develops on the skin after years of sun exposure.

However, they are different from the skin growths mentioned above. Seborrheic keratoses have a waxy look. They look as if they were pasted on the skin. Some may look like a blob of brown candle wax on the skin, while others have the appearance of the barnacles that stick to the legs of a pier.

Seborrheic keratoses:

usually start off as small, rough bumps, which gradually get thicker and develop a warty surface
have a waxy appearance, and look as I they have been stuck on the skin
are brown in color, but may be various shades between white and black
can range in size from tiny to over 1 inch (2.54 centimeters) across
may itch
are not painful

What are the causes of seborrheic keratosis?

Dermatologists are not completely sure why seborrheic keratoses develop.

Sunlight - as they most commonly appear in parts of the body that are more exposed to sunlight, many suggest that ultraviolet light may play a role.

Genetics - seborrheic keratoses seem to run in families. Scientists at the University of Regensburg in Germany reported in the Journal of Investigative Dermatology that a mutation of a gene coding for a growth factor receptor appeared to be linked to seborrheic keratosis.

The British Association of Dermatologists says they are caused by a build up of ordinary skin cells.

Unlike moles, seborrheic keratosis is not caused by a virus.
Diagnosing seborrheic keratosis?

When the growth is very dark, doctors usually recommend a biopsy, to rule out melanoma

The doctor should be able to diagnose seborrheic keratosis after a visual and physical examination.

As the darker lesions may sometimes look like skin cancer (nodular melanoma), the doctor may recommend taking a biopsy which will be examined under a microscope.

In an analysis of 9204 cases of diagnosed seborrheic keratosis, researchers at Massachusetts General Hospital and Harvard Medical School reported in JAMA Dermatology that 61 cases (0.66%) were found to be of melanoma after taking biopsies and testing them (histological examinations).

If the seborrheic keratosis is on the skin and is very thin, it might be hard to rule out lentigo maligna (cancer cells that do not appear to have spread).
Treatment for seborrheic keratosis?

If the doctor is sure it is seborrheic keratosis and not something more serious, he or she will explain that no treatment is needed.

Removal of the growth may be recommended if:

It is hard to distinguish from skin cancer.
The patient does not like it and wants it removed.
It causes problems with clothing or jewelry (rubs against it).

On most occasions, if a biopsy is to be done the dermatologist will probably remove the seborrheic keratosis.

There are several ways of removing seborrheic keratosis:

Cryosurgery - liquid nitrogen is applied to the growth with a spray gun or cotton swab. The lesion instantly freezes and falls off in a few days. A blister may form when the growth falls off, it will eventually dry into a crust, which will fall off.

Electrocautery (electrosurgery) and/or cutterage - an electric current is used to burn (cauterize) the growth. An anesthetic is administered to the area before the procedure begins. The doctor uses a curette, a scoop-shaped surgical instrument, to scrape off the burnt growth, this is called cutterage.

Some patients may require just electrocautery, some cutterage, and others both.

Ablation - this means vaporizing the growth with a laser.

The Mayo Clinic in the United States says that most insurance companies and Medicare do not pay for the removal of seborrheic keratoses if done just for cosmetic reasons. The British Association of Dermatologist also informs "Such treatments may not be funded by the local NHS service."

After the seborrheic keratosis has been removed, the skin in that area may be lighter, and also some surrounding skin. In time this usually fades, but not always.

In the vast majority of cases, the growth does not return, but new ones may appear in other parts of the body.
Video - Seborrheic keratosis

In the video below, dermatologist Kevin St.Clair M.D., discusses the diagnosis and management of seborrheic keratoses.

Written by Christian Nordqvist

Copyright: Medical News Today

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