There is no perfect way of knowing if a small kidney mass is cancer (malignant) or whether it is not (benign) without removing the whole mass. It is preferable not to do this type of surgery if the mass is benign because it can harm your kidney function.
To tell if the mass is actually cancer, your doctor may recommend another imaging test or a biopsy to test for cancer before a treatment option is chosen.
Imaging tests (MRI or CT) use pictures of your small kidney mass to make predictions about when a tumor is benign or malignant, and if it is malignant, what type of kidney cancer it is. If you already had a CT scan, the MRI may or may not be recommended for more information about the mass.
Biopsy is a procedure where a needle is used to take out one or more tiny pieces of the mass while you are under light anesthesia (sleepy but still aware of what is going on). This anesthesia is also called light sedation.
Not all patients with small kidney masses will have these tests recommended.
