Atypical mole syndrome

What are the aims of this leaflet?

This leaflet has been written to help you understand atypical mole syndrome. It tells you what it is, what causes it, what can be done about it and where you can find out more about it.

What is atypical mole syndrome?

Atypical mole syndrome is a disorder of the skin which is seen in approximately 2% of the population. It is defined when an individual has more than 50 moles composed of melanocytes (pigment producing skin cells) present on their skin, and three or more are atypical (unusual) in their appearance, such as their size, shape or colour. An atypical mole is one greater than 5 mm in diameter, often with flat and raised areas, oval rather than round, and with some colour variation.

Solitary atypical moles are individually benign moles with a low risk of progression to melanoma (a type of skin cancer). However, people with multiple atypical moles (atypical mole syndrome) are considered to have a higher risk (increased 7 to 10-fold) of developing melanoma compared to the general population, due to the presence of atypical moles especially if some of these moles are on the scalp, buttocks, or feet. The risk is increased further if one or more first or second degree relatives (i.e. a close blood relative including parents, full siblings or children, or a blood relative including grandparents, grandchildren, aunts, uncles, nephews, nieces or half-siblings, respectively) have been diagnosed with malignant melanoma; this combination is known as familial atypical mole syndrome.

What causes atypical mole syndrome?

It is likely that both genetic causes and ultraviolet (UV) radiation have a role to play in development of atypical moles. The Caucasian population, especially Celtic (fair-skinned) people, are much more prone to developing multiple atypical moles, whereas the condition is rare in other ethnic groups.

Is atypical mole syndrome hereditary?

Yes, it is a hereditary condition; however, it may also occur sporadically with no family history.

What are the symptoms of atypical mole syndrome?

There may be no symptoms at all with atypical mole syndrome, other than the appearance of the moles themselves. It is also possible for new moles to appear over time, for existing moles to itch, become crusted or inflamed, or for a mole to change in size, shape or colour.

What does atypical mole syndrome look like?

Atypical moles are generally larger than normal moles (greater than 5 mm in diameter), have irregular borders and some asymmetry meaning that they are often oval rather than round. Their colour varies from pink to dark brown and they are usually flat or slightly raised from the surface of the skin. They can be positioned on any part of the body, but are most commonly found on sun-exposed areas such as the scalp, upper limbs and trunk. Atypical moles may resemble a melanoma in appearance; however, they do not have other features of melanoma such as persistent and ongoing change.

How is atypical mole syndrome diagnosed?

Atypical mole syndrome can often be recognised by its appearance, if examined by a dermatologist. If there are any concerns over the diagnosis your doctor can arrange for the mole to be removed and examined under a microscope. A set of baseline photographs of the entire skin surface are sometimes requested to facilitate monitoring of the moles.

People who have atypical mole syndrome, or familial atypical mole syndrome, are at an increased risk of developing melanoma and therefore it is recommended that the skin is checked, on a regular basis, for any changes (as mentioned under the Self care (What can I do?) section).

Can atypical mole syndrome be cured?


How can atypical mole syndrome be treated?

An individual atypical mole can be removed surgically if the dermatologist is concerned about it. However, most moles will not require removal, and any surgical procedure carried out will, inevitably, leave a scar.

Self care (What can I do?)

Check your skin for changes once a month. A friend or family member can help you, particularly with checking areas that you cannot easily inspect such as your back. If you notice any changes, present to your GP.

Top sun safety tips

Sun protection is recommended for all people. It is advisable to protect the skin from further sun damage.

Vitamin D advice

The evidence relating to the health effects of serum vitamin D levels, exposure to sunlight and vitamin D intake, is inconclusive. People who are avoiding (or need to avoid) sun exposure may be at risk of vitamin D deficiency and should consider having their serum vitamin D levels checked. If the levels are low, they may consider:

·         taking vitamin D supplements of 10-25 micrograms per day

·         increasing intake of food rich in vitamin D such as oily fish, eggs, meat, fortified margarine and cereals.

Where can I get more information about atypical mole syndrome?

Web links to detailed leaflets:

British Association of Dermatologists

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

Published on:
October 31, 2023

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