Moles

Moles are common skin growths which are usually benign but can sometimes undergo change to become a malignant melanoma.

The medical term for moles is melanocytic naevi as they are due to a proliferation of the pigment cells (melanocytes).

If they are brown or black in colour they may also be called pigmented naevi. Moles are benign in nature, but a malignant melanoma (cancerous mole) may start within a benign mole.

Moles may be flat or protruding from the skin. They vary in colour from pink or flesh tones to dark brown or black. Although mostly round or oval in shape, they are sometimes unusual shapes and range in size from a couple of millimetres to several centimetres in diameter.

The number of moles a person has depends on genetic factors and on sun exposure; most Pakeha New Zealanders have 20-50 of them. People with a greater number of moles have a higher risk of developing melanoma than those with just a few moles, especially if they have over 100 of them.

When do moles first appear?

One or more moles may be present at birth. These brown birthmarks are known medically as congenital melanocytic naevi. Other birthmark like moles can appear within the first two years of life.

More frequently moles arise during childhood or early adult life, when they are called acquired melanocytic naevi. Exposure to sunlight increases the number of moles. Teenagers and young adults tend to have the greatest number of moles and there are fewer in later life because some of the moles fade away over time.

Classification of moles

The conventional classification of melanocytic naevi depends on their appearance under a microscope . They are described according to the site of the naevus (mole) cells in the skin.

Junctional naevi

Junctional naevi have groups or nests of naevus cells at the junction of the epidermis (outer layer of the skin) and the dermis (inner layer). These tend to be flat colourful moles.

Dermal naevi

Dermal or intradermal naevi have naevus cell nests in the dermis. These moles are thickened and often protrude from the skin surface. They may be pigmented or skin-coloured.

Compound naevi

Compound naevi have nests of naevus cells at the epidermal-dermal junction as well as within the dermis. These moles have a central raised area and may be surrounded by flat pigmentation.

A new classification of moles relies on their appearance on dermoscopy,  a technique used by doctors to evaluate the structure of moles using a hand-held magnification device. Dermoscopic patterns of melanocytic naevi include:

• Reticular naevi
• Globular naevi
• Blue naevi
• Starburst naevi
• Site-related naevi
• Naevi with special features
• Unclassifiable naevi

The best way to monitor moles, particularly if you are in a high risk group is to have a full body skin check including a special diagnostic intrument called dermoscopy. Mole map is not as useful as this is just serial photography but moles of concern will be mapped for comparison ifthey do not requireimmediate punch biopsy or excision.  At Palm Clinic Dr Martin Denby, or Dr John Barrett offer full body skin checks with dermoscopy.  If they are concerned that you may have a type of skin cancer depending on the size and site of the lesion they can perform a punch biopsy and surgical excision at Palm Clinic.

Benign moles can be removed for cosmetic reasons using Surgitron radifrequency which is less likely to leave a scar than a surgical excision.

Palm Clinic is now an Affiliated Provider to Southern Cross Health Society for skin checks, skin biopsies, liquid nitrogen and skin cancer surgery. Medical necessity must apply.

.