Seborrheic keratosis is the presence of a benign (non-cancerous) raised growth on the skin. Seborrheic means greasy (although often the growth is not greasy) and keratosis means thickening of skin. The growths arise from the top layer of skin and can have a ‘stuck-on’ look. These growths may look like warts but don’t extend deep into the skin or contain the viruses that cause warts.

Seborrheic keratoses are not contagious, do not spread and will never turn into cancerous tumors. Therefore, they do not threaten your health, but can be irritating or cosmetically displeasing.

Causes

The direct cause of seborrheic keratoses is unknown. However, they are not caused by exposure to sunlight. In addition they appear after the age of 40 and are hereditary.

Risk Factors

Risk factors for developing seborrheic keratoses, include age over 40 and close family members with the condition.

Symptoms

Seborrheic keratosis:

• Can be located anywhere on body, but usually appear on the chest, torso, face, shoulders, or back

• Are typically yellow, tan, brown, or black

• Are elevated off the skin surface

• May have a rough or wart-like texture

• May have a pasted look, as if a blob of dirt or clay is stuck on the skin

• Usually have a round or oval shape

• Can be single or multiple growths

• May be itchy

• Can be irritated by clothing or jewelry and can bleed if picked or rubbed

Diagnosis

Since some seborrheic keratoses appear dark, they may difficult to distinguish from pigmented growths that are prone to becoming cancerous. Therefore it is very important that you have a doctor check and ensure that they are seborrheic keratoses. Doctors can usually make an accurate diagnosis upon examination of the skin growth, but a biopsy can be done to make sure in uncertain cases.

Treatment

Talk with your doctor about the best treatment plan for you. Because seborrheic keratoses do not pose a threat to your health, the best course of action may be to leave them alone. However, if they itch or become irritated, or if you feel they affect your appearance, they can be removed.

Treatment options include:

Topical medications

Alpha-hydroxy lotions or mild steroid creams help with itching and irritation, but do not remove the lesion.

Cryosurgery: Removal by Freezing

Liquid nitrogen is used to freeze and destroy the cells of the seborrheic keratosis but leave the underlying connective tissue intact. This procedure leaves a crust that falls off after several days. There might be a flat scar or lighter colored skin.

Surgical removal: Scraping or Shaving off

Your doctor can use a scalpel or razor to cut the growth off leaving a little scarring.

Laser Removal

The growths can be burned off with a laser (rarely necessary).

RESOURCES:

Academy of Dermatology
http://www.aad.org/

DermAtlas (photos)
http://dermatlas.med.jhmi.edu

CANADIAN RESOURCES:

Canadian Dermatology Association
http://www.dermatology.ca/english/

Dermatologists.ca
http://www.dermatologists.ca/index.html

References:

American Osteopathic College of Dermatology website. Available at: www.aocd.org/skin/dermatologic_diseases/seborrhiec_keraotos.html. Accessed August 22, 2005

National Library of Medicine and the National Institutes of Health website. Available at: http://www.nlm.hih.gov/medlineplus/encyclopedia. Accessed August 22, 2005