Seborrhoeic Keratosis

What are seborrhoeic keratoses?

Seborrhoeic keratoses, also called seborrhoeic warts or basal cell papillomas, are very common, harmless skin growths. Despite the name, they are not warts, are not caused by a virus and have nothing to do with oil glands. They are not cancerous and do not become cancerous.

Who gets them?

They are extremely common and become more common with age. More than half of men and over a third of women in the UK have at least one. About 30 in 100 people have them by the age of 40, rising to about 75 in 100 by the age of 70. Many people develop dozens over time. They affect all skin types. In people with brown and black skin, many small, dark seborrhoeic keratoses on the face and neck are called dermatosis papulosa nigra.

What causes them?

The cause is not fully understood. Age is the main factor. A tendency to develop them can also be inherited, and sun exposure may play a part.

Are they hereditary or contagious?

A tendency to seborrhoeic keratoses can be passed down in families. They are not contagious and cannot be passed on.

What do they look and feel like?

Seborrhoeic keratoses typically have a stuck-on appearance, as if they could be picked off the skin. They have a waxy, rough or warty surface, sometimes with tiny plugs or cracks, and range in colour from pink or light brown to almost black. They may be flat or raised, and can measure anything between a few millimetres and several centimetres. They most commonly appear on the trunk, head and neck, but can occur anywhere except the palms and soles.

They are usually painless but can be itchy, become irritated, catch on clothing, jewellery or bra straps, or bleed if knocked. Many people find them cosmetically troublesome.

How are they diagnosed?

Seborrhoeic keratoses are usually easy to recognise, especially with a dermatoscope, which shows characteristic features. However, some, particularly dark or irritated ones, can look similar to melanoma or other skin cancers. If there is any doubt, a biopsy may be taken. Any new, rapidly changing or unusual-looking growth should be checked rather than assumed to be a seborrhoeic keratosis.

What are the treatment options?

Dr Mounsey will confirm the diagnosis using a dermatoscope and reassure you that seborrhoeic keratoses are harmless. Treatment is not needed, but they can be removed if they catch on clothing, itch or are unsightly. Removal is often regarded as cosmetic. Options include cryotherapy, curettage and cautery, or shave excision, all of which he carries out himself. Where the diagnosis is uncertain, the lesion can be removed and sent to the laboratory.

What is the outlook?

Seborrhoeic keratoses are harmless and do not need to be removed for medical reasons. They do not usually go away on their own, and new ones tend to appear over time.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/seborrhoeic-keratosis

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.