OTHER than Cancer, What could a kidney mass be?

My doctor is still trying to figure out what this mass is on my kidney. If it is not cancer anyone have any other ideas of what it could be?

A Kidney Stone?

A kidney mass may not be cancerous all the times. For example, simple cysts, a type of renal mass, are often benign, meaning that they require no additional treatment.

It is better to wait for the doctor's opinion IMO.