what causes moles

Moles are small, dark marks that appear on the skin and are usually round or oval in shape. They are caused when cells that produce pigment, called melanocytes, grow in groups. Most people have 10 to 40 moles that appear during childhood and adolescence and may change in appearance or fade over time. The number of moles is mainly caused by the genes you inherit, but exposure to sunlight, especially in childhood and early teenage years, can lead to new moles developing. Moles can develop anywhere on your body, including your scalp, armpits, under your nails, and between your fingers and toes. Moles are usually harmless, but some people have a higher-than-average risk of their moles becoming cancerous and developing into melanoma. Factors that increase melanoma risk include being born with large moles, having dysplastic nevi, and having a family history of melanoma. If you notice changes in a moles color, height, size, or shape, or if it starts to itch, bleed, or become painful, you should have a dermatologist evaluate it.