Mole Removal Surgery

Mole Removal Surgery

The average adult has between 15 and 40 moles, but how and when do they develop?

Skin Pigmentation

The outer layers of the human skin contain specialist cells known as melanocytes. These produce the hormone melanin, a pigment that gives the skin its characteristic color.  Typically, people with few melanocyte cells have light-colored skin whereas those with an abundance of cells have dark skin.

Moles, referred to as nevi or nevus in dermatology, are small, dark patches on the skin. According to The American Academy of Dermatology, they are formed when the melanocyte cells cluster together instead of being evenly distributed throughout the body. Moles can be both flat and raised and come in a variety of shapes, sizes and colors including brown, blue, black and tan. They can be present at birth, acquired through life or appear as the result of a hereditary disease.

Birth Moles (Congenital Nevi)

According to The American Academy for Dermatology, one percent of babies are born with at least one mole. These birthmarks are known as congenital nevi and are the result of a skin defect. As Dr Greene, Clinical Professor of Paediatrics at Stanford University, explains congenital nevi that are “smaller than ¾ inch in diameter are called small nevi. Those larger than 7.5 inches in diameter are called giant nevi.”

Acquired Moles (Acquired Nevi)

Acquired moles are a form of localized benign neoplasm (tumour). These moles are more common than birth moles and are developed in early adult life. As consultant dermatologist Professor James Ferguson highlights “most of these [acquired] moles appear during the first 20 years of life, although they may continue to develop into the 30s and 40s. However, the majority disappear with age.” Acquired moles are a common occurrence with the average adult developing 15-40 moles during the course of their life.

Exposure to the sun’s ultra violet light increases the occurrence of acquired moles. A study in the June 2000 edition of the Journal of the American Medical Association (JAMA) followed 458 Caucasian children over a three year period. One group of children were told to use Sun Protection Factor (SPF) 30 whenever they were exposed to the sun’s rays whereas the other group were given no instructions. The results showed that the group that received regular sun protection developed significantly fewer moles than the group without. The number and size of acquired moles can also increase with hormonal changes such as pregnancy, the menopause and puberty.

Atypical Mole Syndrome (Dysplastic Nevi)

Atypical Mole Syndrome, or dysplastic nevi, is a hereditary condition that causes the sufferer to develop a large quantity of moles, commonly over 100. Many of these moles will be larger than normal or atypically shaped. People with this condition are more likely to develop melanoma, a form of skin cancer and so should have their moles regularly checked by a doctor or dermatologist.


The vast majority of moles are a harmless, natural occurrence. However, a mole that changes shape or color, bleeds or itches, needs to be checked by a doctor as it could be a sign of malignant melanoma, or skin cancer.  According to Dr. Greene, there is an “A, B, C, D, E” mnemonic that helps people check for cancerous moles. Here, ”A” stands for asymmetry, “B” for borders, “C” for color, “D” for diameter and “E” for evolving. Unusual moles only occur in 10% of the population and, of these, only one in 10, 000 is a malignant cancerous mole. However, early detection can stop the spread of the disease and so it is worth checking your body regularly for unusual moles.

The American Academy of Dermatology (AAD) is the world’s largest organization of dermatologists. More information can be found at

Professor James Ferguson is Consultant Dermatologist at the University of Dundee. More information can be found at

Dr Alan Greene is Clinical Professor of Paediatrics at Stanford University School of Medicine. More details of his credentials can be found at

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