Lebret T et al. (2007) Percutaneous core biopsy for renal masses: indications, accuracy and results. J Urol 178: 1184–1188

Most suspicious solid renal masses are found by radiological imaging, and are treated by radical nephrectomy; however, not all solid masses turn out to be malignant, so some operations are unnecessary for satisfactory long-term results.

The increasing sophistication of imaging techniques has enabled more accurate differentiation between benign and malignant lesions; however, interpretation can still be difficult in some cases, particularly if the tumor is smaller than 40 mm. Lebret et al. have assessed the accuracy and safety of image-guided renal tumor biopsies in patients with smaller tumors and where radiological information is not conclusive.

They performed a total of 119 percutaneous core biopsies of renal masses over a 6-year period. Benign lesions were diagnosed in 20.1% of biopsies and malignancy was identified in 58.8%. No accurate diagnosis was possible in 21% of biopsies, but repeat biopsies in 13 patients identified a total of 11 malignant lesions. A total of 64 nephrectomies were performed, and assessment revealed that biopsy accuracy for histopathological tumor type was 86%. A period of watchful waiting was proposed for 31 patients and no renal malignancies were found. CT showed stabilization or disappearance of the initial renal mass.

The authors conclude that percutaneous renal tumor biopsies are safe, cost-effective and mostly conclusive for an acute histological diagnosis. They stress that this procedure could aid accurate diagnosis and clinical decision-making, and could allow patients with benign lesions to avoid nephrectomy.