Advice with injury or sickness !

Is anyone able to help me identify what this rash or scratch is on my boy ? A yellow pinky mark on his skin, fur in that area has disappeared aswell. He’s had it for at least a week now. And it hasn’t affected his behaviour in any way. We haven’t taken him to the Vet yet but will do if needed !

Any info would be greatly appreciated!

Any questions please ask aswell.