Hi, My 12 Year Old Son Has A Large Dark

Hi, my 12 year old son has a large dark brown mole on the nape of his neck. The paediatrician told me at birth that I was to have it checked when he is older. In the past week I have noticed that the hair on it is beginning to turn white/grey.

Is there a need for me to worry and do I need to bring him to a dermatologist?

Regards,
Lora