Diagnostic Efficacy of Percutaneous Renal Tumor Biopsy - Concomitant Use of Frozen Section to Accurately Diagnose Renal Tumor with Necrosis.

OBJECTIVES:To evaluate the diagnostic efficacy of percutaneous renal tumor biopsy. METHODS:We retrospectively investigated 23 patients who underwent percutaneous renal tumor biopsy since 2008 at Department of Renal and Urologic Surgery, Asahikawa Medical University Hospital. We examined indications of biopsy, diagnostic concordance rate between urologists, radiologists and biopsy findings, pathological findings and biopsy-related complications. RESULTS:Renal tumor biopsy was performed under ultrasonography guidance in 21 patients and computed tomography guidance in 2. The most frequent indication to perform biopsy was to determine histological subtype of renal cell carcinoma(RCC)before treatment. The second indication was to clarify the nature of renal tumor. Biopsy findings revealed RCC in 17 patients and urothelial carcino- ma(UC)in 6. Diagnostic concordance rate between urologist's diagnosis and biopsy findings was 91%(21/23), which showed the same result between radiologists and biopsy findings. Biopsy-related adverse event included needle tract implantation in 1 patient with UC. Another patient who had central necrosis in the tumor showed insufficient material causing repeat biopsy with frozen section. Except this patient, initial renal tumor biopsy was successful in all patients by concomitant use of frozen section for tumor with central necrosis. The overall diagnostic rate of initial biopsy was 95.7%(22/23). CONCLUSIONS:Despite a small number of patients and a retrospective nature, the present study shows that renal tumor biopsy plays an important role in diagnosis of renal tumor. Concomitant use of frozen section might be considered at the time of renal tumor biopsy in patients with necrotic renal tumor to avoid repeat biopsy. However, we should take into consideration that there are some possible risks of needle tract implantation in cases with UC when we perform percutaneous renal tumor biopsy.