Seborrhoeic warts

What are seborrhoeic warts?

Seborrhoeic warts are also known as seborrhoeic keratoses. In the past they were also called senile warts. They usually look like greasy or crusty spots which seem to be stuck on to the skin. The colour varies but usually they are darkish brown or black.

They are usually round although they can also be oval in shape. Some seborrhoeic warts have an irregular shape. Their size can vary from around one centimetre to several centimetres in diameter.

Seborrhoeic warts tend first to appear around the age of 40. They can sometimes run in families. The actual cause of seborrhoeic warts is unknown. It can be common to develop several seborrhoeic warts as you become older. Also, as time goes by, each wart tends to grow slightly and become darker. They can occur anywhere on your body, other than on your palms or soles.

Black pigmented verrucous lesion

By Alborz Fallah (Own work), CC BY-SA 3.0, via Wikimedia Commons

Seborrhoeic keratosis

By Lmbuga (Own work), Public domain, via Wikimedia Commons

Are seborrhoeic warts serious?

No. Seborrhoeic warts are always benign. That means they do not spread and they are not cancerous. The main problem is that they can sometimes look unsightly, particularly if they develop on your face.

Very rare cases have been reported of a type of skin cancer called melanoma developing within a seborrhoeic wart. It is not known if this is just a coincidence or whether it represents a true cancer change in the seborrheic wart. If you do notice a change in a seborrhoeic wart, it is worth asking your doctor to examine it.

Note: although they are called warts, they are not caused by the wart virus. They are not infectious.

Can seborrhoeic warts be treated?

If they do not cause any problems then it is best that they be left alone. Without treatment, they usually continue to grow and can become darker and more crusty. However, they do increase in size very slowly.

If required, however, they can be removed quite easily. Seborrhoeic warts are usually removed because they itch, they interfere with clothing or jewellery or they are unsightly.

Two commonly used methods to remove them are:

• By using a curette. This involves 'freezing' the surrounding skin with local anaesthetic. The seborrhoeic warts are then scraped off with a sharp surgical instrument called a curette.

• Liquid nitrogen treatment. Liquid nitrogen is very cold and anything it touches is killed by the cold. Small amounts of liquid nitrogen can be sprayed on to small seborrhoeic warts. The seborrhoeic warts are killed and drop off a few days later. Normal skin replaces the area left behind. Liquid nitrogen is not suitable for larger warts.

Once seborrhoeic warts have been removed, they usually do not return.