Small Renal Mass

A 65-year-old man with a history of well-controlled hypertension presents for a follow-up visit after an incidental finding of a small mass in the right kidney on an abdominal computed tomographic scan (ordered to evaluate lower-quadrant pain, which has since resolved). The mass is 3.2 cm, anterior, heterogeneous, and solid, and is in the right renal hilum near the main renal artery, vein, and ureter; the left kidney appears normal. The patient feels well, his physical examination is unremarkable. His serum creatinine level is 1.2 mg per deciliter. How should this patient be further evaluated and treated?