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Seborrhoeic Keratoses: Causes and Treatment Options

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Seborrhoeic Keratoses (SKs) are common, benign (non-cancerous) growths that can occur almost anywhere on the skin. Some people get just one; others develop many.

Seborrhoeic Keratoses

Usually beginning as small, rough bumps, SKs tend to eventually thicken and develop a warty surface. They can be flat or raised. Most are brown but can range in colour from light tan to black. Some SKs measure a fraction of an inch; others are larger than a half-dollar. Sometimes the surface feels smooth. What often distinguishes these growths from other lesions is a waxy, stuck-on the-skin appearance.


The exact cause remains unknown. SKs seem to run in families, and it appears that some people inherit a tendency to develop many. Although these growths develop on both sun-exposed and non-sun-exposed skin, some studies suggest that sun exposure may play a role. And while SKs may seem to multiply and spread to other areas, they are not contagious.

happy woman in a bicycle

Those At Risk

Anyone can develop SKs but usually these growths generally first appear in middle age or later. Occasionally, SKs erupt during pregnancy or following estrogen therapy. They are rarely found on children.

Where They Appear

Most often form on the chest and back but can SKs also can be found on the scalp, face, neck, or almost anywhere on the skin. They do not develop on the palms or soles.

When Treatment Is Needed

Since SKs are benign, treatment is generally not necessary. However, sometimes SKs grow quickly, turn black, itch, or bleed, making it difficult to distinguish from skin cancer. Such growth should be biopsied to determine if it is cancerous or not.

Occasionally, numerous new SKs develop suddenly. This can indicate a serious health problem. If this
occurs, see a doctor.

Treatment may be recommended if the growth is large or easily irritated by clothing or jewellery. Sometimes, an SK is treated because the patient considers it unsightly.

doctor checking skin cancer

Treatment Options

  1. Cryosurgery

Liquid nitrogen is applied to the growth with a cotton swab or spray gun. This “freezes” the growth. The SK usually falls off within days. Sometimes a blister forms under the SK and dries into a scab-like crust that falls off. After the growth falls off, a small dark or light spot may appear on the skin. This usually fades over time. A permanent white spot is a possible side effect of this treatment.

  1. Electrosurgery and curettage

Electrosurgery involves anaesthetizing (numbing) the growth and using an electric current to cauterize (burn) the growth. A scoop-shaped surgical instrument, a curette is used to scrape off the treated lesion. This is the curettage. Stitches are not necessary. There may be minimal bleeding, which is controlled by applying pressure or a blood-clotting chemical.

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