Moles (naevi)

What is a mole?

A mole (also known as a naevus, pleural naevi) is a collection of pigment cells, known as melanocytes in the skin. Most individuals with European skin will have some naevi.

Naevi come in many shapes, size and colours. Their shape can be can be round or oval and asymmetrical shape is less likely to be concerning. They usually measure less than a quarter-inch in diameter (about the size of a pencil eraser). They are often brown, black, or tan, and can be smooth, wrinkled, flat, or raised. Some naevi have hair growing from them.

Naevi can appear alone or in groups.

The majority of moles are entirely harmless (benign) but rarely, can become malignant. If this happens it becomes a malignant melanoma, a type of skin cancer, which can spread to other organs in the body.

What causes a mole?

Naevi may be present at birth (congenital) or develop through life (acquired). Congenital naevi tend to be darker and larger than acquired naevi and may become thickened on the surface and hairier with time.

What are the different types of mole?

There are several types of moles. The most common are:

  • Acquired moles (common moles) these appear after birth. Most people who have acquired moles have more than one, often between 10 and 40 of them. Moles are most likely to appear up to age 25.
  • Congenital moles are present at birth. They are slightly more likely to develop into the more serious type of skin cancer–melanoma–than moles that appear after birth, especially if they are very large.
  • Dysplastic moles also called atypical moles, these may have more than one colour and irregular edge. Dysplastic moles have a small but higher chance of developing into melanoma. If you have a dysplastic mole, you should have your Dermatologist check the mole regularly.
  • Spitz naevus moles are typically pink, raised, and shaped like a dome. They might be red, black, brown, or multi-coloured. They might also bleed. These moles should be monitored regularly by your Dermatologist.

A mole that has changed character can be a sign of melanoma and it is important it is checked out by a dermatologist without delay. Although melanoma can be deadly, it is highly treatable if caught early.

An easy way to remember what to look for when checking your moles is to follow the ABCDE checklist.

If any of your moles show any of these signs, then have it checked out by our Dermatologists.

  • Asymmetry—if you draw an invisible line down the middle of the mole, one half of the mole doesn’t match the other half
  • Border—the edges of the mole are ragged or irregular
  • Colour—the colour of the mole is not the same throughout or there are multiple colours visible within the mole
  • Diameter—the mole is larger than a pencil eraser
  • Evolution—the mole changes in size, shape, or colour

What are the treatments for moles?

If you are worried because a mole has changed character, then arrange to see one of our Dermatologists who will check if it is harmful. In some cases, he/she may recommend a biopsy which is performed under local anaesthetic.

Moles can also be removed if they are a nuisance or appear unsightly. For cosmetic removal of moles, our Dermatologist may refer you to one of our Plastic surgeons.

01709 464200 




By submitting information on this form you are giving us permission to contact you regarding your enquiry.

This information will NOT be used for marketing purposes.