They might look unusual but are generally benign. Most people have moles. Only about one in a hundred persons has a mole or moles present at birth. These so called congenital melanocytic naevi are often bigger than acquired naevi moles that develop after birth. Moles typically appear in childhood and early teenage years, so that by the age of 15, Australian children have an average of more than 50 moles.
Like moles, the colour associated with freckles is due to the presence of melanin that is formed in melanocytes that has appeared or darkened with sun exposure. Moles appear when skin cells form a cluster. Freckles have a normal number of pigment-producing cells and cannot turn into moles. Most moles are harmless. However, some types can develop into skin cancer. Overexposure to the sun, especially in childhood, can increase the number of moles, and people with a lot of normal moles can have a higher risk of developing melanoma.
Irregular moles dysplastic or atypical naevi are a sign that a person has an increased risk of developing melanoma and the risk increases with the number of moles a person has.
Not all spots that appear on your skin are cancerous. Anyone can develop sunspots, also known as actinic or solar keratoses, but they more often occur in people aver the age of Sunspots usually appear on skin that is frequently exposed to the sun such as the hands, forearms, lower legs, neck and head.
They are a warning sign that the skin has had too much exposure to the sun and this can increase the risk of developing skin cancer. Moles can be benign or cancerous. Cancerous moles, such as melanomas, develop as a result of genetic mutations. The exact cause of benign moles remains unknown. Common moles can appear at birth or later in childhood.
These moles usually appear on areas of the skin that a person exposes to sunlight. A common mole typically has a round, symmetrical appearance with a smooth surface and a defined border. Common moles are relatively small, measuring less than 5 millimeters mm in diameter. These moles rarely develop into cancer. However, people who have more than 50 common moles may have a higher chance of developing melanoma, according to the National Institutes of Health NIH.
Congenital moles, or birthmarks , are present at birth. Congenital moles can vary drastically in size with some being quite large. However, figures may vary from study to study. Atypical moles, or dysplastic nevi, can develop anywhere on the body and usually appear larger than other mole types. Their color and texture can vary, and they usually have an uneven border that fades into the surrounding skin.
According to the American Cancer Society , some atypical moles may become cancerous. However, most atypical moles do not develop into melanomas. Since atypical moles may show some similar characteristics to melanoma, people should visit their dermatologist to be sure that there are no concerns. This rare type of mole looks a lot like melanoma, but it is not cancerous.
It usually develops in fair skinned children and young people under 20 years old. However, some people who are diagnosed with melanoma have few moles, and melanoma often develops in areas of the body that are not exposed to the sun. Researchers are working to identify additional susceptibility genes to better understand the genetics of moles and their relationship with cancer.
The natural history of common melanocytic nevi: a systematic review of longitudinal studies in the general population. J Invest Dermatol. Epub May Atypical mole syndrome and dysplastic nevi: identification of populations at risk for developing melanoma - review article. Clinics Sao Paulo. Topics in the Genetics and Human Traits chapter Are fingerprints determined by genetics? Is eye color determined by genetics? Is intelligence determined by genetics?
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