S.O.
Most people have areas of different pigmentation. I think you might be worrying too much. I have a patch of very light skin on my right leg and a small blog of very dark skin on my left hip.
My blonde son has a patch of white hair right above one ear. It's been there since he was 7.
Be careful when doing online research for health. There are a lot of scare stories posted out there by non-medical professionals.