Dark line / Circle around neck

I'm hoping someone can help me out with this, I have a dark ring / line on my neck region. I have asked my GP before and he said it was normal. There seems to be thinning on the skin as well. If anyone has any suggestions I would be happy. I have included a few images, hope it helps.

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It looks very much like Acanthosis Nigricans.Its usually seen in skin folds especially in overweight people and the solution is usually to lose weight. Its not harmful in itself but sometimes can be an indication of something else like diabetes.Has your GP suggested a blood test to rule this out?
You can try a skin lightening cream…there are lots on the market and online but try talking to your pharmacist to get recommendations.You could also try lathering your neck using a soft brush when you wash your hair or shower.

Thank you for your response Marina_Dee.