The latest advance in Mole Diagnosis, Mapping and Treatment

Taranaki's only dedicated Skin Cancer Unit

One of these moles will kill you, the other is harmless. Do you know which one it is? With the naked eye its very hard to be sure

What are moles?

Moles are common, usually harmless, skin lesions. They are correctly called melanocytic naevi as they are due to a proliferation of the pigment cells, melanocytes. Moles can be flat or protruding. They vary in colour from pink flesh tones to dark brown or black. The number of moles a person has depends on genetic factors and on sun exposure; most New Zealanders have 20 - 50 of them.

Melanocytic Naevi may be present at birth (congenital) but more usually begin to grow during childhood. New moles can appear at any age though incidence does decrease with age. Early naevus cells form nests on the junction between the epidermis (outer layer of the skin) and the dermis (inner layer) so are known as junctional naevi. These are flat moles.

Naevus cells can also form in the epidermis and the dermis (compound naevi) or may be found in the dermis (intradermal naevi). These moles are thickened and often protrude from the skin surface. Heavily pigmented dermal naevi often appear blue (blue naevi).

Moles may darken following sun exposure or during pregnancy. During adulthood they may lose their pigmentation, and they may even disappear in old age.

ATYPICAL MOLES (Dysplastic Naevi)

Atypical Naevi, also called Clarks Naevi or Dysplastic Naevi, are moles that have unusual features such as an indistinct edge and/or larger size. They often resemble a cancerous mole (melanoma), but are actually benign. Because of their worrying appearance, they are often removed. Dermoscopic examination can be very helpful in distinguishing these from melanomas. People with atypical naevi have an increased risk of developing melanoma.

CONGENITAL PIGMENTED NAEVUS (CPN)

This is the name for a mole present at birth. One in a hundred babies has a congenital naevus varying in size from a few millimetres in diameter to covering half the baby's skin. There may be an increased risk of melanoma developing within congenital naevi, especially very large ones, so if any change has been noted it should be checked.

HALO NAEVUS

Sometimes the skin around a mole losses its colour so the mole appears to be surrounded by a white ring. This 'halo' naevus occurs most often in children and teenagers. It is harmless, and with time the central mole and white ring disappear. It is caused by the body’s immune system attacking the melanocytes.