What are the aims of this leaflet?

This leaflet has been written to help you understand more about dysplastic naevus (moles). It explains what they are, what causes them, what can be done about them, and where you can find more information about them.

What is a dysplastic naevus?

The word “dysplastic” means that the mole is odd looking but is not cancerous. Normal moles are clusters of skin pigment cells (melanocytes), small and uniform in colour and structure. The melanocytes in dysplastic moles become irregular.

If you are diagnosed with one dysplastic mole, you are more likely to be diagnosed with another at some point in time.

What causes a dysplastic naevus?

People with lighter coloured skin are more likely to develop dysplastic moles. In fact, about one in fifteen white people have at least one dysplastic mole. Those who are at greater risk of developing a dysplastic mole include:

• Lighter coloured skinned, red haired and blue-eyed individuals
• People with previous history of dysplastic mole(s)
• Those who have a rare condition called atypical mole syndrome, which can be inherited
• People who have had bad sunburn as a child. However, not all dysplastic moles are related to sun exposure and may appear in areas that are not usually exposed to the sun.

Is dysplastic naevus hereditary?

Atypical mole syndrome (a rare condition which can cause dysplastic moles) can be inherited.

It is also important to remember that factors such as lighter skin colour and red hair can be inherited, and individuals with these features are at increased risk of dysplastic naevus.

However, the majority of dysplastic moles are not hereditary (they are instead called ‘sporadic’).

Although some dysplastic moles may turn into a skin cancer called melanoma, most do not. However, people with dysplastic mole syndrome are at a higher risk of developing a melanoma over the course of their life.

What are the symptoms of a dysplastic naevus?

A dysplastic mole appears different to a typical mole in size, shape, and colour. Dysplastic moles do not usually itch, bleed, or become inflamed.

What does a dysplastic naevus look like?

A dysplastic naevus tends to be larger than a normal mole, measuring 5 - 10 mm or more. It may have irregular, indistinct borders and can have multiple colours such as shades of tan, brown, pink, and black. Dysplastic moles may be flat or raised.

How is a dysplastic naevus diagnosed?

Dysplastic moles may be diagnosed by your GP or more likely a specialist doctor. They will make a diagnosis by looking at the size and variation in colour and shape. The mole may be removed surgically under local anaesthetic and sent to a pathologist for assessment. Once looked at under a microscope, the pathologist can advise if the mole is dysplastic. Some dysplastic moles are difficult to tell apart from melanomas, therefore the safest way forward is to remove them.

Can a dysplastic naevus be cured?

Yes, a dysplastic naevus can be completely removed by a small operation using a local anaesthetic. Once the mole has been fully removed it should not come back.

How can a dysplastic naevus be treated?

If a mole is very different from your other moles, your specialist may advise that it to be removed surgically under local anaesthetic. The removed mole will then be sent to a pathologist to be analysed under a microscope.

If the dysplastic naevus is mildly or moderately abnormal when checked by the pathologist and the mole was completely removed, there is usually no need for any further treatment. However, if the pathologist finds that there are more severe changes, then sometimes you may be advised to have a further operation under local anaesthetic. This is to remove some extra skin around the site of the previously removed mole, with a safety margin of healthy-looking skin around it, as a precaution. This further surgery is called a ‘wide local excision’.

Some people have many dysplastic moles, and it is not practical to remove them all. If you have this problem, then it is important to monitor your skin, as described below.

Self-care (What can I do?) 

• Monitor your skin regularly to look out for any signs that the moles may be turning into melanomas. This involves checking all your skin including hairline, soles of feet, armpits, and buttocks. You must check for asymmetry, irregular edges, colour changes and an increase in size of the mole. To do this, you can use the ‘ABCDE’ guide, used by healthcare professionals when diagnosing dysplastic naevus. This guide looks for the following features of a mole:

Asymmetry – the two halves of the area differ in their shape.

Border – the edges of the area may be irregular or blurred, and sometimes show notches.

Colour – this may be uneven. Different shades of black, brown, and pink may be seen.

Diameter – most melanomas are at least 6 mm in diameter.

Evolution – rapid changes in a pre-existing mole.

• It may be helpful to take one set of whole-body pictures on your phone at different time points so that you can compare your moles and notice any changes.

• You should be careful not to get sun-burned or get too much sunlight. This means covering up with long sleeves, trousers, and a hat on sunny days, if possible. Sunbeds and sun tanning are best avoided completely.

• It is recommended that you wear sun protection cream SPF 50 between the months of March and October on all sun exposed areas, such as hands, face, ears, and neck. Sunscreen is best used half an hour before going outside. It is advisable to apply some more sun cream every couple of hours if you are out and about. Choose SPF 50 with five stars for maximal UVA and UVB cover.

• Sunscreens should not be used as an alternative to clothing and shade; rather, they offer additional protection. No sunscreen will provide 100% protection.

• Sunshine is the most important source of vitamin D so make sure to maintain a varied diet rich in Vitamin D. It is advised that everybody should take vitamin D tablets over the winter period. These can be bought from a chemist or supermarket.  You may also need to take vitamin D in the summer if you are being very careful about sun protection.  Sometimes a blood test for vitamin D levels can be helpful to guide this.

Where can I get more information about dysplastic naevus?

Web links to detailed leaflets:

https://dermnetnz.org/topics/atypical-melanocytic-naevus

https://www.skincancer.org/risk-factors/atypical-moles/

https://www.pcds.org.uk/clinical-guidance/atypical-dysplastic-melanocytic-naevus

Jargon Buster: https://www.skinhealthinfo.org.uk/support-resources/jargon-buster/

Please note that the BAD provides web links to additional resources to help people access a range of information about their treatment or skin condition. The views expressed in these external resources may not be shared by the BAD or its members. The BAD has no control of and does not endorse the content of external links.

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

BRITISH ASSOCIATION OF DERMATOLOGISTS PATIENT INFORMATION LEAFLET

PRODUCED MAY 2022

NEXT REVIEW DATE MAY 2025