Had this same thing. Turned out to be nothing. I think he'll be alright, hopefully. They'll do more scans for him to make sure.
a mass is different from cyst which might was in your case biopsy is not advisable in case of mass, only surgical removal will be the option
renal mass exclusively used to describe a tumors ,we shoud agree to this . a cyst ultrasound looks distinctively different and wont be interchangeably named a mass even without additional CT/MRI so your Doctor is fine with a kidney tumors ?
I did a kidney ultrasound. They found what was described as a "hump", described potentially as both a cyst and mass at various points. They sent me for a CT and was then described as a "dromedary hump" of no concern. The reporters who are reporting this aren't doctors or even science journalists. Its entirely possible that something is lost in translation between what the doctors say, and what comes out via team sources to sports reporters.