Moles

Published by Bupa's Health Information Team, March 2010.

This factsheet is for people who have moles, or who would like information about them.

A mole (melanocytic naevus or melanonaevus, plural naevi) is a small, dark area of skin. Moles are usually circular or oval-shaped. They may be present at birth, but most appear later. They may change shape or colour over time and some may even drop off completely.

Moles are usually harmless but sometimes they can become cancerous.

About moles

Moles are areas of skin where cells called melanocytes have grouped together. Melanocytes produce a pigment called melanin which gives your skin its colour - where they cluster together the skin is darker. You may have moles when you're born, but they usually develop later in childhood.

Moles vary in colour from flesh-coloured to dark brown. They may be raised or have hairs growing out of them.

The medical term for moles is naevi (plural) or nevus (singular).

Types of moles

There are many different types of moles. Some types look very similar to one another and it can be hard to tell them apart. They can also be confused with other skin conditions such as freckles and warts.

Moles that you're born with are called congenital moles. They are usually at least 1cm across but can be much bigger. As you grow, they tend to grow with you and may become more raised and hairier as you get older.

Moles that appear after you're born are called acquired moles. Some of the different types are described here.

• Junctional melanocytic naevi are flat and round. They are usually mid to dark brown.
• Compound melanocytic naevi are slightly raised and are often hairy. Their colour can vary.
• Dermal melanocytic naevi are raised bumps and often hairy. They may not be any darker than the rest of your skin.
• Blue naevi are dark blue and are usually found on the face, hands or feet.
• Halo naevi are more common in children and teenagers. These moles have a pale ring around them and may go away by themselves.
• Dysplastic naevi often appear in groups. They are often larger than other moles and can vary in shape, size and colour.

You may develop seborrhoeic warts (keratoses) later in life. They aren't actually moles, although they are often a similar colour, but are caused when ordinary skin cells build up. Seborrhoeic warts don't develop into cancer.

Symptoms of moles

Most moles are harmless and don't cause any problems. Some moles can become sore or inflamed.

Complications of moles

Certain types of moles are more likely to develop into skin cancer.

• If you have a congenital melanocytic naevus, there is a chance that it may become cancerous, particularly if it's large.
• Dysplastic naevi are more likely to progress into a malignant melanoma (a type of cancer).

It's a good idea to check your moles regularly so that you're aware if any of them change shape or colour. See your GP if you notice:

• an existing mole has grown
• a mole with a ragged/uneven edge
• a mole that has varying shades of colour
• a mole that bleeds, oozes or crusts
• a mole that feels painful or itches
• a mole where the two halves don't look the same

An easy way to remember these changes and what to do if you notice any of them is to use the ABCDE method.

A - asymmetry
B - border
C - colour
D - diameter
E - evolving (a mole that is changing in size, shape or colour)

Causes of moles

The exact reasons why you may develop moles aren't fully understood at present. However, many types seem to run in families, particularly dysplastic naevi. The likelihood of having lots of moles also seems to be inherited. If you have fair skin you will probably have more moles.

You're also more likely to have moles if you spend lots of time in the sun, especially if you have done so since childhood.

Moles can also change or appear because of changes in your hormones. This commonly occurs during puberty or during pregnancy.

Diagnosis of moles

Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history. Your GP may take a photo of your mole so that at your next appointment he or she can see if it has changed at all. This is called mole mapping. There are also lots of clinics that offer a mole mapping service.

You may need to have a biopsy of your mole. A biopsy is a small sample of tissue. This will be sent to a laboratory for testing to determine the type of cells and if these are benign (not cancerous) or cancerous.

It's possible that you will be referred to a dermatologist - a doctor who specialises in skin conditions.

Treatment of moles

Even if your mole isn't cancerous, you may want to have it removed - for example if it catches on things. Some people wish to have it removed for cosmetic reasons.

The exact procedure to remove your mole will vary depending on what type of mole you have.

• A shave biopsy - the top layer of skin is taken off using a blade.
• A punch biopsy - a disc of skin and tissue is removed.
• An excision biopsy - the entire mole is removed.

You may need to have stitches depending on the size of the mole and whether any of the surrounding skin cells are removed. If it's small, your doctor may just burn (cauterise) the area underneath where the mole was. This seals the blood vessels so stitches aren't needed. You will usually be given a local anaesthetic before any of these procedures are done. This completely blocks pain from the area and you will stay awake during the operation.

Living with moles

The more moles you have, the higher your risk of developing skin cancer. So, if you have a lot of moles, you should take extra care to look after your skin when you're out in the sun. This can help to prevent sunburn, which can increase your chance of developing skin cancer. If you're spending longer than a few minutes out in the sun:

• wear at least SPF15 sunscreen
• cover up with a hat, T-shirt and sunglasses
• seek shade when you can at the hottest times of the day (usually between 11am and 3pm)

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.