Seborrheic Keratosis

What is seborrheic keratosis?
Seborrheic keratoses are very common skin growths. These growths are totally benign and cannot turn into cancer. They usually appear after the third decade of life and are seen increasingly with age. Yet, they cannot be considered a sign of aging, since they are found as early as in the twenties and thirties.

The reason for the appearance of seborrheic keratoses is unknown; most likely, genetic predisposition is responsible. Sunburns and sun exposure are not associated with seborrheic keratoses.

Seborrheic keratoses may first appear as brown flat growths (macules). Later they can develop into waxy, raised, brown to black thick protrusions (plaques). Their appearance is usually described as “stuck-on”. In other words, they look as if they can be easily separated or “taken off” of the skin. Seborrheic keratoses may be seen anywhere on the skin, except mucous membranes, palms, and soles.

When is appearance of seborrheic keratoses important?

Since seborrheic keratoses are benign, their presence is not detrimental to health. There is, however, one scenario when it is important to address the presence of seborrheic keratoses. If multiple lesions suddenly appear or increase in size, an internal cancer (colon, rectum, stomach, breast, and others) is possible. This eruption (sign of Leser-Trelat) is most commonly seen on the chest and back. It is important to mention that this sign of Leser-Trelat is very rare. Most seborrheic keratosis lesions gradually appear on the skin, and have no health consequences.

If your doctor suspects Leser-Trelat, he or she may order blood work, chest X-rays, mammography, evaluation of gastrointestinal tract, and other testing if symptoms are present.

Seborrheic keratoses are usually treated only if they are irritated or cosmetically displeasing to the patient. Various destructive modalities are successfully used to remove the lesions. These include cryotherapy (freezing the lesions with liquid nitrogen), electrodesiccation (cautery with electric current), curettage (scraping), surgical removal, laser removal, and dermabrasion.

Alexander Doctoroff, D.O., F.A.O.C.D.
Assistant Chief of Dermatology,
Veterans Administration Medical Center
East Orange, New Jersey

Assistant Clinical Professor of Medicine,
University of Medicine and Dentistry of New Jersey