Yes, melanomas can arise from pre-existing moles, so we do have to vigilant to detect any changes in the moles. As you have rightly pointed out, changes in the size and in the colour of the moles and important signs to look out for in a changing mole.
Melanomas are one of the most sinister skin cancers as they have a potential to spread or metastasize. It is important to detect melanomas early as this can significantly improve the prognosis and outcome.
You can see your dermatologist if you have any concerns for a detailed examination of the moles. A dermatoscopic examination can be done to examine the mole in greater detail and the doctor can then advise you on how to proceed from there, including a skin biopsy if needed.
