What are the aims of this leaflet?
This leaflet has been written to help you understand more about melanocytic naevi. 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 melanocytic naevi?
The lay term for a melanocytic naevi is a “mole”. The word ‘melanocytic’ means that they are made up of the cells (melanocytes) which produce the dark pigment (melanin) that gives the skin its normal colour. Melanocytes cluster together to form naevi. In other words, moles are localised and benign accumulations of melanocytes.
Some moles (congenital melanocytic naevi) are present at birth. Most come up later (acquired melanocytic naevi). Most people have at least one acquired mole and many people have several moles. Some come up in early childhood, and others come up later, particularly during adolescence and pregnancy. Some even go away in old age.
What causes melanocytic naevi?
Their cause is not fully understood. A genetic factor is likely. Another factor is exposure to too much sun in childhood, as those who grow up in the sunniest countries tend to have the most moles. Moles are most common in people with fair skin.
Are melanocytic naevi hereditary?
A tendency to have many ordinary melanocytic naevi runs in some families. ‘Dysplastic naevi’ (see below), in particular, tend to run in families.
What are the symptoms of melanocytic naevi?
Usually there are none. Some people do not like the appearance of their moles. Raised moles may catch on things. Moles may become sore and inflamed after hairs have been plucked out of them.
What do melanocytic naevi look like?
Those that are present at birth (congenital melanocytic naevi) are seldom less than 1 cm in diameter but can be much larger. They grow in proportion with you as you grow. They are dark and tend to become more raised and hairy with age.
There are three main types of acquired melanocytic naevi:
Junctional melanocytic naevi are flat, and usually circular. Their colour is usually even, and ranges from mid to dark brown.
Compound melanocytic naevi are raised brown bumps, most of which are hairy. Some have a slightly warty surface.
Dermal melanocytic naevi are raised, often hairy, bumps, looking like compound naevi, but are more pale coloured.
In childhood, most moles are of the junctional type. Later in life some become raised and more hairy.
There are several other, less common, types of mole. They include the ‘blue naevus’ (a harmless mole that has a dark blue colour), the ‘halo naevus’ (a mole surrounded by a pale ring which may gradually go away by itself), and ‘dysplastic naevi’ (these are usually multiple, with irregular pigmentation and shape, and run in some families. They have a greater tendency than most moles to change into a melanoma, which is a cancer of moles).
How will melanocytic naevi be diagnosed?
Most moles can be recognised easily by their appearance. If there are any worries over the diagnosis, particularly over the possibility of a melanoma (see below), your doctor will arrange for the mole to be removed and checked in the laboratory. It may occasionally be hard to tell a mole from a ‘seborrhoeic keratosis’ (a harmless dark warty area that is common in older people).
Can melanocytic naevi be cured?
Yes. They can be removed surgically if necessary, but most are best left alone.
How can melanocytic naevi be treated?
There are three main reasons for removing moles:
- The most important reason is doubt about the diagnosis. The mole then has to be checked under the microscope. The main worry is usually whether or not the mole is a melanoma. The changes that suggest this are described in more detail in the British Association of Dermatologists’ information leaflet entitled Melanoma. In brief, they include changes in size (getting bigger), shape (becoming asymmetrical with an irregular ragged edge) or colour (an uneven colour with different shades of black brown or pink). Suggestive symptoms include itching and a tendency to bleed, ooze or crust. melanomas.
- The mole has become a nuisance by catching on clothing or being cut while shaving.
- Cosmetic reasons.
If there is any doubt about the diagnosis, the mole should be cut out completely under a local anaesthetic. Other techniques can be used for moles being removed because of their cosmetic appearance or have become a nuisance. These include shaving the mole off, if it is raised (shave excision) and then touching the raw area left behind with a hot point (cautery).
Self care (What can I do? )
If you have a large number of moles:
You should examine your skin monthly for moles that are growing, or changing in the ways described above. If you find any worrying changes, or one that is clearly different from the rest, you must contact your doctor immediately.
You must also protect yourself from too much sun exposure. This does not mean that you can’t ever go on a sunny holiday again; it just means that you need to be careful to avoid sunbathing and burning. You should cover yourself up and use sun protection creams (see the ‘top sun safety tips’ below for more information).
Top sun safety tips
Protect your skin with clothing, and don’t forget to wear a hat that protects your face, neck and ears, and a pair of UV protective sunglasses.
Spend time in the shade between 11am and 3pm when it’s sunny. Step out of the sun before your skin has a chance to redden or burn.
When choosing a sunscreen look for a high protection SPF (SPF 30 or more) to protect against UVB, and the UVA circle logo and/or 4 or 5 UVA stars to protect against UVA. Apply plenty of sunscreen 15 to 30 minutes before going out in the sun, and reapply every two hours and straight after swimming and towel-drying.
Keep babies and young children out of direct sunlight.
The British Association of Dermatologists recommends that you tell your doctor about any changes to a mole or patch of skin. If your GP is concerned about your skin, make sure you see a Consultant Dermatologist – an expert in diagnosing skin cancer. Your doctor can refer you for free through the NHS.
Sunscreens should not be used as an alternative to clothing and shade, rather they offer additional protection. No sunscreen will provide 100% protection.
It may be worth taking Vitamin D supplement tablets (available from health food stores) as strictly avoiding sunlight can reduce Vitamin D levels.
Vitamin D advice
The evidence relating to the health effects of serum Vitamin D levels, sunlight exposure and Vitamin D intake remains inconclusive. Avoiding all sunlight exposure if you suffer from light sensitivity, or to reduce the risk of melanoma and other skin cancers, may be associated with Vitamin D deficiency.
Individuals avoiding all sun exposure should consider having their serum Vitamin D measured. If levels are reduced or deficient they may wish to consider taking supplementary vitamin D3, 10-25 micrograms per day, and increasing their intake of foods high in Vitamin D such as oily fish, eggs, meat, fortified margarines and cereals. Vitamin D3 supplements are widely available from health food shops.
Where can I get more information about melanocytic naevi?
Web links to detailed leafets: