Replying to Knee injury that confused my doctor

so after getting an MRI i went to an orthopedic surgeon. apparently i have a mass inside of my knee. its not really connected to anything, just there. well my doctor who's been practicing for over 20 years has no idea what the hell it is. he's sending me to get a biopsy and a bone screening, then is sending my MRI to some convention of doctors. its seriously fucked up. and my knee doesn't even hurt.

has anyone heard of anything like this before? its just a mass like 2 cm in diameter in the middle of my leg above my knee. i'm startin to freak out cuz they're thinking i'm gonna have to have it cut out