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Seborrhoeic keratosis


What are the aims of this leaflet?

This leaflet has been written to help you understand more about seborrhoeic keratoses. It tells you what they are, what causes them, what can be done about them, and where you can find out more about them.

What are seborrhoeic keratoses?

Seborrhoeic keratoses (SK) are also known as seborrhoeic warts, and as basal cell papillomas. They are benign growths due to a build-up of skin cells. SK are very common, harmless, often pigmented, growths on the skin. In the UK more than half the men and more than third of women would have at least one SK. By the age of 40 30% of the population would be affected while by the age of 70 it increases to 75%. They are also found in younger people. Some people will have only few seborrhoeic keratoses, while others will have large numbers.

They are not infectious and do not become skin cancer.

What causes seborrhoeic keratoses?

Despite their name, SK are nothing to do with sebaceous glands or viral warts. We don’t know what causes them. It has been suggested that exposure to sunlight and the human papilloma virus (HPV) are risk factors.

Are seborrhoeic keratoses hereditary?

Yes, some individuals may inherit the tendency to develop SK from their parents.

What are the symptoms of seborrhoeic keratoses?

SK are harmless, and usually do not cause symptoms. They can sometimes itch, become inflamed, and catch on clothing. Many people dislike the look of them, particularly when they occur on their face.

What do seborrhoeic keratoses look like?

SK have a rough surface, and range in colour from golden brown to mid brown to almost black. They can affect anyone, but on dark- skinned people they can also appear as multiple small dark brown or black bumps, especially on the face and the neck; in such a case this is called Dermatosis Papulosa Nigra. 

Small flat SK can often become more raised and larger as the years go by. Their size varies from less than one centimetre to severalcentimetres across. They give the impression that they are stuck onto the surface of the skin; however, some look like small pigmented skin tags.

SK occur most often on the trunk, but they are also common on the head and neck. Their numbers vary, and one person may have just one seborrhoeic keratosis whilst others can have hundreds. Once present, they usually stay, and new ones often appear over the years.

How are seborrhoeic keratoses diagnosed?

SK are much more common than skin cancers; however, a very dark seborrhoeic keratosis can look similar to a melanoma. It is therefore important that either a general practitioner or specialist checks any pigmented lesions to ensure that the correct diagnosis is made.

SK can cause worry by becoming inflamed or bleeding. If there is any doubt, a skin biopsy can be done to confirm the diagnosis.

Can seborrhoeic keratoses be cured?

Individual SK can be treated successfully in the ways listed below. However, new SK may continue to appear.

How can seborrhoeic keratoses be treated?

As SK are so common, it would be impossible to routinely treat every individual and every single keratosis. Most need no treatment as they are harmless and cause no symptoms; however, for those who wish to have some of their keratoses removed it may be possible to have them treated by a general practitioner in primary care. SK are not routinely removed in hospitals.  Treatment can occur by either freezing them with liquid nitrogen (cryotherapy), or scraping them off (curettage) under a local anaesthetic.

Such treatments may not be funded by the local NHS service.

What can I do?

Always contact your doctor if you are worried about a pigmented spot that is changing in any way.

Where can I get more information about seborrhoeic keratoses?

Web link to detailed leaflets:

For details of source materials used please contact the Clinical Standards Unit (

This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor.

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel


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