Moles, which are also referred to as melanocytic naevi, are skin lesions that can be located anywhere on the body. Because moles vary in size and shape many people believe they are caused by a virus but there has been no evidence found to prove that theory.
Moles are caused by a sudden abnormal growth of melanocytes cells, which are responsible for giving skin its natural colour and protecting it from ultraviolet radiation. Moles are the result of the accumulation of these cells causing the skin to become considerably darker than normal skin tone. Moles can be present at birth or develop during the first 30 years of life.
The appearance of moles varies in location, size and colour. People with lighter skin tend to have more moles, which are also a darker brown colour. They are normally small in size, rarely exceeding half an inch in diameter and can be bumpy or flat.
Moles can become cancerous and cause malignant melanoma. The exact cause of malignant melanoma is not known though it is generally thought to be the result of excessive exposure to the sun or genetic factors. Moles that change in colour or size, become red and itchy or begin to bleed could be an indication of malignant melanoma. It is important to check moles regularly and look for any changes in their appearance.