Mole (skin marking)A mole is a small spot of darkened pigment on the skin, which forms where there is a high concentration of melanin. Moles are usually circular or oval and not very large. Some children are born with moles, and almost everyone has at least one or two moles on their bodies. Sudden and unexpected changes in skin moles (eg.bleeding, irritation, darkening, sudden growth) can be a sign of skin cancer so they need to be watched carefully. If a mole appears suspicious, it will be biopsied and checked for signs of malignancy.