What are my chances that my kidney tumor is benign?

UroToday – Incidence of Benign Pathologic Findings at Partial Nephrectomy for
Solitary Renal Mass Presumed to be Renal Cell Carcinoma on Preoperative Imaging

The authors conclude that there is no reliable
indicator of benign pathology preoperatively in solitary renal masses, as
all of these were considered to be renal cell carcinoma on preoperative
imaging. Overall, management of these tumors should favor parenchymal
sparing approaches that can be both diagnostic and therapeutic, while
preserving functional renal mass.

Urologists once told patients that 90-95% of solid masses were malignant. We are now finding smaller tumors incidentally (by ultrasound or CT Scan done for another reason) and the likelihood of not having cancer has increased. I currently tell patients they usually have about a 15-20% chance of having a benign lesion if it is small (under 4 cms). I agree that in most cases, nephron sparing procedures (partial nephrectomy, cryosurgery or RF ablation) should be recommended.