What does these 'spots' mean?

I have a cat. Its a siberian cat. you know those very hairy cats? well i have one. its a gray young male. he is soon going to be 2 years. His name is Bruno and its a home/inside cat. He's castrated and have no other animal around since I live in a small department with no yard. so the question is, I've notice that some yellowish spots are growing in his ear skin, i mean inside his ears. first it was only on the right ear, then the spots appeared on both ears, these spots have started to appear since maybe october from last year. since they are definitely not going away Im a bit concerned about the issue. please let me know anything you might know about these case. :)