Diagnostic value of CT-guided biopsy of indeterminate renal masses

To evaluate the role of percutaneous core biopsies in the diagnosis of renal masses that could not be classified as benign or malignant based upon imaging alone.

We retrospectively analysed core biopsies of indeterminate renal masses of 23 patients who were referred to us for computed tomography (CT)-guided biopsy from 1996-2001. Follow-up ranged from 1-5 years. Analysis was based on indications for biopsy, size and characteristics of the lesion and accuracy of biopsy results.

There was one technical failure in 22 patients included in the analysis. Fifteen core biopsies revealed malignancies that were confirmed either clinically or surgically. Seven were benign, one of which was false-negative. The sensitivity was 93%, specificity 100%, positive predictive value 100% and negative predictive value 75%. The results in tumours <==3 cm were similar to those in larger lesions.

We recommend the use of core biopsy as a diagnostic tool for indeterminate renal masses, regardless of mass size. Renal core biopsy can influence the management of lesions: primary renal lesions are resected, while treatment for metastatic disease is tailored to the primary tumour. Tumours with benign biopsy results should be re-evaluated and either referred for resection of the mass or followed up closely with clinical observation and of imaging studies.