Diagnostic Accuracy of Computed Tomography-Guided Percutaneous Biopsy of Renal Masses

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1 european urology 53 (2008) available at journal homepage: Kidney Cancer Diagnostic Accuracy of Computed Tomography-Guided Percutaneous Biopsy of Renal Masses Joerg Schmidbauer a, *, Mesut Remzi a, *, Mazda Memarsadeghi b, Andrea Haitel c, Hans Christoph Klingler a, Daniela Katzenbeisser a,c, Helene Wiener c, Michael Marberger a a Department of Urology, Medical University of Vienna, Vienna, Austria b Department of Radiology, Medical University of Vienna, Vienna, Austria c Department of Pathology, Medical University of Vienna, Vienna, Austria Article info Article history: Accepted November 14, 2007 Published online ahead of print on November 26, 2007 Keywords: Biopsy Carcinoma Computed tomography Kidney Renal cell cancer Abstract Objective: Modern imaging modalities increase the detection of small (4 cm) renal tumors, of which about 20% are benign. As a result, minimal invasive treatments, such as radiofrequency ablation and cryotherapy, and surveillance strategies are gaining popularity. Information that would be helpful when choosing the most appropriate management strategy for this patient group could be obtained from pretherapeutic image-guided biopsy. Methods: Under computed tomography (CT)-fluoroscopic guidance 78 patients with solid renal tumors prospectively underwent 18-gauge core biopsy. In addition, using the same sheath, fine-needle aspiration was taken in 44 patients and analyzed cytologically. The renal masses were subsequently removed surgically and evaluated histologically. Results: Mean patient age was yr; mean tumor size was cm. The sensitivity of core biopsy and fine-needle aspiration for the detection of renal cell carcinoma (RCC) was 93.5% and 90.6%, respectively; Fuhrman grade was correctly predicted in 76% and 28% and the correct histologic subtype was identified 91% and 86%, respectively. Cytology from fine-needle aspiration revealed a sensitivity in detecting malignant and benign lesions of 100% and 75%, respectively. Two of the renal tumors diagnosed as oncocytomas on core biopsy were hybrid tumors with scattered areas of oncocytomas and chromophobe RCC. Complications of CT-guided biopsy included one marginal pneumothorax, which resolved under conservative management, and four small perirenal hematomas detected at follow-up ultrasonography not requiring further therapy. Conclusion: CT-guided percutaneous preoperative renal tumor biopsy had a high diagnostic accuracy, particularly in predicting malignancy. # 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved. * Corresponding authors. Department of Urology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. Tel ; Fax: addresses: joerg.schmidbauer@meduniwien.ac.at (J. Schmidbauer), mremzi@gmx.at (M. Remzi) /$ see back matter # 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved. doi: /j.eururo

2 1004 european urology 53 (2008) Introduction The incidence of renal cell carcinoma (RCC) has been rising over the past decades, with the greatest increase observed in small (4 cm), incidentally detected lesions [1]. Due to the widespread use of conventional imaging modalities, such as computed tomography (CT), ultrasonography, and magnetic resonance imaging (MRI), at cross-sectional examinations most renal tumors are found incidentally [2]. Partial nephrectomy remains the cornerstone of treatment for small renal masses, providing excellent renal and oncologic outcomes, with a 5-yr cancer-specific survival rate of % [3]. However, it has to be taken into account that 20% of small renal masses are actually benign [4], and RCC lesions <3 cm in diameter demonstrate fewer aggressive features than lesions 3 4 cm in diameter [5]. As a result, and because elderly patients afflicted with comorbidities often represent poor candidates for surgery [2,6], surveillance strategies have been developed. However, even modern imaging techniques are unable to predict the aggressiveness of small renal tumors or to detect benign lesions, such as oncocytomas and low-fat angiomyolipomas [4,7,8]. Measuring the growth rate of lesions using serial radiographies has also been insufficient to predict the true natural history of renal masses [9]. As well as interobserver and intraobserver variability in measuring tumor diameter [10], additional inaccuracies may be expected because tumor volume is exponentially related to tumor diameter [2]. As a consequence of the difficulty in predicting whether a tumor is benign or malignant, biologic data are needed to assess the natural history of either untreated renal masses under active surveillance or when energy ablative techniques are proposed ahead of final histology results. Today, the challenges in the adequate diagnosis and treatment of small renal tumors include the identification of tumors with less aggressive potential, treating less aggressive tumors less invasively, and certifying tumor control after less invasive therapy. To this end, image-guided biopsy could provide information that may be helpful when deciding on the most appropriate management strategy for these patients. 2. Methods From December 2005 to May 2007, we prospectively evaluated the diagnostic accuracy of pretherapeutic percutaneous biopsy of renal masses guided by CT in 118 consecutive patients. Patients with cystic lesions and patients with suspected transitional cell carcinoma were excluded. Seventy-eight of these patients underwent CT-guided tumor mass core biopsy and 44 underwent fine-needle aspiration cytology (FNAC). The mass was then completely removed in a separate surgical session and analyzed histologically. In the other 39 patients the tumor was treated with energy ablative techniques (14 percutaneous radiofrequency ablation [RFA], 11 laparoscopic RFA, 14 cryoablation) and therefore not available for histologic comparison with core biopsy and FNAC results. In one patient the biopsy revealed a metastasis of lung cancer. These 40 patients were therefore excluded from analysis. Patients were fully informed about benefits and risks of this approach and patients signed a written informed consent prior to the biopsy procedure. All specimens were reviewed by the same pathologist (A.H.) and were classified using the Heidelberg system [11]. Aspiration cytology was performed by H.W Biopsy technique The patients were placed in a prone position. Under local anesthesia, and using helical CT-fluoroscopy guidance, a 17- gauge coaxial needle (Bard 1 TruGuide TM, Covington, GA, USA) was directed to the tumor (Fig. 1). The stylet was removed and FNAC was performed. After the sample was dried, it was immediately analyzed by a cytopathologist. Through the same sheath, an 18-gauge core biopsy needle (Bard 1 Magnum TM, Covington, GA, USA) was inserted to obtain two or three core biopsies for histologic evaluation. Two-hour postinterventional ultrasound examination was performed to rule out postbiopsy hematomas Statistics Sensitivities, specificities, positive predictive values (PPVs), and negative predictive values (NPVs) were calculated for FNAC and core biopsy. In all patients who underwent surgery after biopsy, histopathologic results were compared and biopsy accuracy was calculated. Insufficient biopsies were excluded for further evaluation of accuracy. 3. Results The mean age of the patients was yr (median: 64 yr; range: yr) and 15 patients (20%) were women. Ninety percent of renal tumors were detected incidentally. Three patients had a tumorbearing solitary kidney and five patients had bilateral tumors; 39 renal tumors were located in the left kidney (51%). Mean tumor diameter on preoperative CT scan was cm (median: 3.9 cm; range: cm); 44 (58%) tumors were small renal tumors (diameter 4 cm). FNAC was insufficient in 11% (Table 1); in one sample, no cells were found, whereas in the remaining four, aspiration revealed blood cells only. Three of the FNAC samples were insufficient and

3 european urology 53 (2008) Fig. 1 Biopsy technique. were taken from the first 10 patients. Only two (3%) of the core biopsies were insufficient, showing normal renal parenchyma. Final histology revealed clear-cell RCC in both patients. FNAC theoretically causes less trauma and hence fewer problems from bleeding. The low complication rate of core biopsy devalued this argument. In view of the higher rate of insufficient samples and the lower diagnostic accuracy in defining RCC subtypes and grade we stopped using FNAC after the first 44 patients. The need for an experienced cytologist also renders FNAC less attractive. Sensitivities, specificities, PPVs, and NPVs for the detection of RCC by aspiration cytology and core biopsy are shown in Table 1. RCC subtype was correctly predicted in 86% using aspiration cytology and in 91% using core biopsy. The accuracy for the differentiation of Fuhrman grade was 28% using aspiration cytology, whereas the correct nuclear grade was identified in 76% of biopsies using core biopsy. The incorrect grade was identified using core biopsy in 24% (n = 14; two grade 3 tumors were incorrectly identified as grade 2, one grade 2 tumor was incorrectly identified as grade 1, and in 11 biopsies no nuclear grade was assigned). FNAC revealed sensitivity in malignant lesions of 100% and 75% in benign tumors. A flowchart of the results of core biopsy is shown in Fig. 2. Core biopsy detected RCC in 58 (74%) patients, transitional cell carcinoma and metastasis each in one patient, and benign histology in 16 (21%) patients (all oncocytomas except two low-fat angiomyolipomas and one cyst). Fig. 3 shows the flowchart of the RCC detected by core biopsy. One patient with a bilateral renal tumor (Fig. 4a) showed a solid renal mass 3 cm in diameter on the right side and a solid renal mass with central necrosis 4.5 cm in diameter on the left side. FNAC and core biopsy were performed on the right side because of easier subsequent management by partial nephrectomy. Core biopsy revealed clearcell RCC Fuhrman grade 2 (Fig. 4b), and final histology confirmed this finding (Fig. 4c). However, no biopsy was performed on the left side. After convalescence of the patient, partial nephrectomy Table 1 Sensitivity, specificity, positive predictive value, and negative predictive value of pretherapeutic computed tomography fluoroscopic-guided percutaneous fine-needle aspiration and core biopsy Aspiration cytology Core biopsy Core biopsy Insufficient 11 (5/44) 3 (2/78) Detection of malignancy * Benign histology True-positive, n False-negative, n False-positive, n 3 True-negative, n Sensitivity 90.6% 95.2% 100% Specificity 100% 100% 95% PPV 100% 100% 81% NPV 70% 81.3% 100% RCC subtype Accuracy 86% (25/29) 91% (53/58) Fuhrman grade Accuracy 28% (8/29) 76% (44/58) PPV = positive predictive value; NPV = negative predictive value; RCC = renal cell carcinoma. * RCC (including one core biopsy showing undifferentiated carcinoma and Fuhrman high-grade RCC in final histology).

4 1006 european urology 53 (2008) Fig. 2 Flowchart of results of core biopsy. Fig. 3 Flowchart of renal cell carcinoma detected by core biopsy.

5 european urology 53 (2008) Fig. 4 Computed tomography (CT) bilateral tumor. (a) CT of a patient with bilateral synchronous renal tumors. (b) Core biopsy of the right renal tumor showing clear-cell RCC G2 (hematoxylin-eosin staining, T100). (c) Final histology of the right renal tumor showing clear-cell RCC G2 (hematoxylin-eosin staining, T200). (d) Final histology of the left renal tumor showing pure oncocytoma (hematoxylin-eosin staining, T40). was successfully performed on the left side. Final histology revealed a pure oncocytoma (Fig. 4d). In two other patients with a 3.7-cm solid renal mass on the left side (Fig. 5a) and a mass 1 cm in diameter on the left side, FNAC and core biopsy showed oncocytoma (Fig. 5b). Following partial nephrectomy, final histology using cytokeratin 7 staining revealed hybrid tumors containing areas of chromophobe RCC (Fig. 5c). In four patients (Fig. 6), final histology demonstrated nests of high nuclear grade in otherwise low-grade RCC. The rate of complications was low. Four minor hematomas were detected on follow-up ultrasonography, none of which required further treatment or delayed surgery. However, one patient experienced a small pneumothorax in an upper pole renal tumor on the right side. The patient did not experience any side effects, but for safety reasons, surgery was delayed for 2 wk. 4. Discussion The goal in the diagnostic work-up of renal masses is to differentiate benign from malignant tumors, and furthermore to better categorize RCCs to enable treatment to be tailored to the patient. This goal is the result of the changing landscape of renal tumors and the treatment modalities currently available [1,2,12,13]. Due to modern crosssectional imaging techniques, a greater number of incidental renal tumors (40 70%) are found, which are often small. As a consequence, the incidence of RCC has increased [1] and, concomitantly, so has the incidence of benign renal masses [14]. It is known that about 20% of all small renal tumors are benign [4] and do not necessarily require treatment.furthermore,jewettandcolleagues[2] have proposed that not even all small RCCs require surgical treatment and that surveillance strategies

6 1008 european urology 53 (2008) Fig. 5 Cytokeratin 7-positive hybrid tumor (a) CT of renal tumor. (b) Core biopsy showing oncocytoma (hematoxylin-eosin staining, T200). (c) Final histology showing hybrid tumor containing cytokeratin (CK) 7-positive chromophobe renal cell carcinoma and CK 7-negative oncocytoma. mightbeadequatetreatmentforsomesmallrenal RCCs. Imaging alone is mostly inadequate for the assessment of solid especially small renal masses, with the exception of typical angiomyolipomas. Only a few studies [7] have reported that homogeneously enhancing and hyperattenuating renal masses on biphasic CT scans are angiomyolipomas containing minimal fat. Kim et al have also reported that the signal intensity index and tumor-to-spleen ratio in angiomyolipomas and non-angiomyolipomas are significantly different, with an area under the receiver operating characteristic curve of 97.5% [8]. In general, however, imaging cannot be used to differentiate benign from malignant solid masses. Remzi et al showed recently that only 17% of all benign renal masses were correctly defined on preoperative CT scans [4]. In previous reports, ultrasonography-guided core biopsy was used [15,16]. Although this avoids radiation exposure we and others have found it difficult to reliably target small renal lesions, especially if <4 cm [14,17,18]. Some of them are isoechoic and difficult to detect by ultrasonography, some neighboring structures such as the pleural fold cannot be discerned, and with the mobility of the kidney, the tumor tends to slip from the tip of the needle when punctured [14,19]. All this is avoided with CT fluoroscopy, as shown by the 3% rate of insufficient biopsies in this series. Advances in cytologic techniques, particularly immunocytochemistry and cytogenetics, have Fig. 6 Nests of grade 3 in low-grade renal cell carcinoma (RCC). (a) Core biopsy showing clear-cell RCC G2. (b) Final histology showing clear-cell RCC G2 with foci of G3.

7 european urology 53 (2008) contributed to the increasing ability to differentiate between benign and different RCC subtypes using percutaneous renal tumor biopsy [14]. The sensitivities, specificities, PPVs, and NPVs of FNAC and core biopsy for the detection of RCC found in the current study are at the higher end of reported series; however, recent studies have also reported similar findings. Earlier in 2007, Maturen et al reported a sensitivity for malignancy of 97.7%, a specificity of 100%, a PPV of 100%, and an NPV of 100% in a retrospective analysis of core biopsies [20]. Overall, most studies have been retrospective, with highly selected patient cohorts and no standardized biopsy protocols. The reported sensitivity of biopsy for the diagnosis of malignancy ranges from 80% to 92%, regardless of the needle size used or whether the specimens were examined cytologically, histologically, or both [14]. False-negative results are most often due to a failure to place the needle tip accurately in a small mass. In the current study only about 3% of percutaneous biopsies showed false-negative results. In the retrospective study by Maturen et al, 4% of biopsies were nondiagnostic, and 5% of samples overall were inconclusive in the series of Neuzillet et al [17,20]. Of small solid renal masses 20% are benign, whereas conversely 20 30% of small renal masses are high grade or pt3 RCC [5]. Although surveillance, nephron-sparing surgery, or energy ablative techniques are gaining popularity but are still not standard, core biopsy may help in the decisionmaking process [13,21,22]. In a retrospective manner biopsy results could have changed management in 19 patients overall. Six patients had low-grade pt1a RCC and were older than 75 yr and 13 had a benign histology. In these patients energy ablative therapy or even active surveillance would have been a potential therapeutic option. Angiomyolipomas are considered difficult to identify on biopsy due to nuclear atypia and pleomorphism comparable to those found in RCC [14]. HMB-45 is constantly expressed by angiomyolipomas but not by RCC or liposarcomas. Additionally, angiomyolipomas are negative for cytokeratin [23]. In our series only two biopsies revealed angiomyolipomas. The series of Neuzillet et al [17] included 10 oncocytomas, three angiomyolipomas, and one cystadenoma. The major diagnostic challenge is represented by oncocytomas. Oncocytotic cells are found in numerous RCCs, such as chromophobe RCC, the granular cell variant of RCC, and the eosinophilic variant of papillary type RCC (type 2). Immunocytochemistry can help to distinguish between RCC and oncocytomas. Liu et al reported that all oncocytomas were vimentin negative, whereas granular cell and eosinophilic papillary RCC were vimentin positive [24]. Chromophobe RCCs are also vimentin negative but can be differentiated from oncocytomas by Hale colloid ferrous staining. c-kit and, as demonstrated in the present study, cytokeratin 7 are useful immunohistochemical stainings for differentiating between cytokeratin 7-positive chromophobe RCC and cytokeratin 7-negative oncocytomas [14]. In the current study one patient presented with bilateral renal masses. Unilateral core biopsy revealed RCC on the right side. The assumption that the same tumor was also present contralaterally proved to be wrong final histology showed pure oncocytoma. Clearly bilateral renal masses, therefore, need bilateral biopsies. Two of our oncocytomas were hybrid tumors containing scattered areas of benign oncocytomas and malignant chromophobe RCC side by side. Both were misdiagnosed on percutaneous biopsy as oncocytoma because biopsy hit only the oncocytoma areas of these hybrid tumors. Dechet et al reported RCC with concomitant oncocytoma in 10% of samples [25]. Only one study [26] prospectively followed 15 patients with oncocytomas diagnosed by percutaneous biopsy using a surveillance strategy. Six of these 15 patients underwent surgery: total nephrectomy in 4 and partial nephrectomy in 2. The indications for surgery were the initial tumor volume (n = 1), tumor growth >0.5 cm/yr (n = 4), and the patient s preference (n = 1). Operated patients were younger ( yr vs yr) and had larger tumors at diagnosis ( mm vs mm) than those who did not undergo surgery. All nine patients treated with watchful waiting were asymptomatic. Gubjartson et al [27] reported capsular penetration in two and focal extension into perinephric fat in one oncocytoma, but diagnosis was made in 1974 and coexisting clearcell RCC (granular cell subtype) in the same kidney was found in two patients. The cytomorphologic features of malignant renal tumors, including RCC and its various subtypes, have recently been better defined. Barocas et al was able to improve the accuracy of subtyping from 90% to 95% by adding molecular diagnosis (in which RNA from core biopsies was extracted and quantitative real-time polymerase chain reaction performed for four gene products to differentiate RCC subtypes) to histopathologic diagnosis [28]. Subtypes of RCC have distinct cytogenetic abnormalities, such as the loss of 3p in clear-cell, trisomy 7 or 17 in papillary, and widespread chromosomal losses in chromophobe

8 1010 [1] Hollingsworth JM, Miller DC, Daignault S, Hollenbeck BK. Rising incidence of small renal masses: a need to reassess treatment effect. J Natl Cancer Inst 2006;98: [2] Volpe A, Panzarella T, Rendon RA, Haider MA, Kondylis FI, Jewett MA. The natural history of incidentally detected small renal masses. Cancer 2004;100: [3] Lane BR, Gill IS. 5-Year outcomes of laparoscopic partial nephrectomy. J Urol 2007;177:70 4. [4] Remzi M, Katzenbeisser D, Waldert M, et al. Renal tumour size measured radiologically before surgery is an unreliable variable for predicting histopathological features: benign tumours are not necessarily small. BJU Int 2007;99: [5] Remzi M, Ozsoy M, Klingler HC, et al. Are small renal tumors harmless? Analysis of histopathological features according to tumors 4 cm or less in diameter. J Urol 2006;176: [6] Chawla SN, Crispen PL, Hanlon AL, Greenberg RE, Chen DY, Uzzo RG. The natural history of observed enhancing renal masses: meta-analysis and review of the world literature. J Urol 2006;175: [7] Kim JK, Park SY, Shon JH, Cho KS. Angiomyolipoma with minimal fat: differentiation from renal cell carcinoma at biphasic helical CT. Radiology 2004;230: [8] Kim JK, Kim SH, Jang YJ, et al. Renal angiomyolipoma with minimal fat: differentiation from other neoplasms at double-echo chemical shift FLASH MR imaging. Radiology 2006;239: [9] Kunkle DA, Crispen PL, Chen DY, Greenberg RE, Uzzo RG. Enhancing renal masses with zero net growth during active surveillance. J Urol 2007;177: [10] Punnen S, Haider MA, Lockwood G, Moulding F, O Malley ME, Jewett MA. Variability in size measurement of renal masses smaller than 4 cm on computerized tomography. J Urol 2006;176: [11] Kovacs G, Akhtar M, Beckwith BJ. The Heidelberg classification of renal cell tumors. J Pathol 1997;183: [12] Klingler HC, Marberger M, Mauermann J, Remzi M, Susani M. Skipping is still a problem with radiofrequency ablation of small renal tumours. BJU Int 2007;99: [13] Remzi M, Memarsadeghi M. Small incidental renal tumors: evaluation and biological parameters. Urologe A 2007;46: [14] Silverman SG, Gan YU, Mortele KJ, Tuncali K, Cibas ES. Renal masses in the adult patient: the role of percutaneous biopsy. Radiology 2006;240:6 22. [15] Johnson PT, Nazarian LN, Feld RI, et al. Sonographically guided renal mass biopsy: Indication and efficacy. J Ultrasound Med 2001;20: [16] Caoili EM, Bude RO, Higgins EJ, Hoff DL, Nghiem HV. Evaluation of sonographically guided percutaneous core biopsy of renal masses. AJR Am J Roentgenol 2002;179: [17] Neuzillet Y, Lechevallier E, Andre M, Daniel L, Coulange C. Accuracy and clinical role of fine needle percutaneous biopsy with computerized tomography guidance of small (less than 4.0 cm) renal masses. J Urol 2004;171: [18] Khan AA, Shergill IS, Quereshi S, Arya M, Vandal MT, Gujral SS. Percutaneous needle biopsy for the indetermieuropean urology 53 (2008) RCC [14]. In a recent study, histopathology correctly identified the tumor subtype in 27 (75%) biopsies; 4 (11%) were incorrectly classified and 5 (14%) biopsies were inadequate for diagnosis. With the addition of fluorescence in situ hybridization (FISH), 31 (86%) were correctly subtyped, whereas 2 (6%) were incorrect and 3 (8%) were inadequate for diagnosis [20]. In our study the accuracy for detecting high and low Fuhrman grade was 76%. Neuzillet et al [17], investigating 88 biopsies performed with CT guidance and 18-gauge needles in small solid masses, reported a concordance of Fuhrman nuclear grade in percutaneous biopsy and histopathologic specimens of only 69.8%. Because Fuhrman grade is a prognostic marker, improvements are needed for a better classification of nuclear grade on biopsy specimens. Percutaneous biopsy of renal masses represents a safe diagnostic procedure with a low rate of complications. In our series, no serious adverse events were reported, and a clinically insignificant subcapsular hematoma was observed on routine sonography in only four patients following biopsy. One patient had a marginal pneumothorax, which resolved under conservative management. The most frequent complication reported is usually hemorrhage, which in the majority of cases occurs without clinical evidence and remains self-limiting. Serious adverse events, such as persistent gross hematuria, retroperitoneal bleeding requiring transfusions, or arteriovenous fistulas are rare (<1%) [14]. 5. Conclusions Pretherapeutic percutaneous core biopsies of renal masses under helical CT guidance provide accurate histopathologic evaluation of kidney tumors that could potentially influence treatment decisions. FNAC did not add information to core biopsy. The high rate of RCC detection on sufficient biopsy is reflected by a specificity of almost 100%. The majority of benign lesions were correctly identified and in five of six RCCs, the correct tumor type was identified. However, hybrid tumors consisting of concomitant chromophobe RCC and oncocytoma currently remain problematic on biopsy. Conflicts of interest The authors have nothing to disclose. References

9 european urology 53 (2008) nate renal masses: a national survey of UK consultant urologists. BMC Urol 2007;7:10. [19] Heidenreich A, Ravery V. European Society of Oncological Urology. Preoperative imaging in renal cell cancer. World J Urol 2004;22: [20] Maturen KE, Nghiem HV, Caoili EM, Higgins EG, Wolf JS, Wood DP. Renal mass core biopsy: accuracy and impact on clinical management. AJR Am J Roentgenol 2007;188: [21] Terrone C, Volpe A. The role of pathology for clinical decision-making in renal cell carcinoma is increasing. Eur Urol 2007;51: [22] Somani BK, Nabi G, Thorpe P, N Dow J, Swami S, McClinton S, Aberdeen Academic and Clinical Urological Surgeons (ABACUS) Group. Image-guided biopsy-diagnosed renal cell carcinoma: critical appraisal of technique and long-term follow-up. Eur Urol 2007;51: [23] Nelson CP, Sanda MG. Contemporary diagnosis and management of renal angiomyolipoma. J Urol 2002;168: [24] Liu J, Fanning CV. Can renal oncocytomas be distinguished from renal cell carcinoma on fine-needle aspiration specimens? A study of conventional smears in conjunction with ancillary studies. Cancer 2001;93: [25] Dechet CB, Bostwick DG, Blute ML, Bryant SC, Zincke H. Renal oncocytoma: multifocality, bilateralism, metachronous tumor development and coexistent renal cell carcinoma. J Urol 1999;162:40 2. [26] Neuzillet Y, Lechevallier E, André M, Daniel L, Nahon O, Coulange C. Follow-up of renal oncocytoma diagnosed by percutaneous tumor biopsy. Urology 2005;66: [27] Gudbjartsson T, Hardarson S, Petursdottir V, Thoroddsen A, Magnusson J, Einarsson GV. Renal oncocytoma: a clinicopathological analysis of 45 consecutive cases. BJU Int 2005;96: [28] Barocas DA, Rohan SM, Kao J, et al. Diagnosis of renal tumors on needle biopsy specimens by histological and molecular analysis. J Urol 2006;176: Editorial Comment on: Diagnostic Accuracy of Computed Tomography-Guided Percutaneous Biopsy of Renal Masses Yasuyoshi Miyata Department of Urology, Nagasaki University School of Medicine, Nagasaki, Japan Int.doc.miya@m3.dion.ne.jp In general, knowing the pathologic diagnosis before the decision is made for treatment strategies, such as ablative approaches or surveillance, is beneficial to patients with a renal mass. However, renal masses, especially small masses, are often difficult to obtain exactly by aspiration and needle biopsy. Therefore, development of precise and safe methods for renal mass biopsy is important for planning treatment strategies for patients with renal cell carcinoma (RCC). In recent years, many investigators have reported on the diagnostic accuracy and complications of image-guided needle biopsy and fineneedle aspiration in patients with renal masses [1 3]. The present study by Schmidbauer et al [4] was performed in a prospective consecutive manner. In addition, the accuracy of needle biopsy was compared to that of fine-needle aspiration. Finally, the study demonstrated that computed tomography-guided needle biopsy was a useful and safe method to provide accurate histopathologic diagnosis of renal masses and that fine-needle aspiration cytology did not provide additional information to a needle biopsy. Based on these results and previous reports, image-guided needle biopsy is recommended to obtain the pretherapeutic pathologic information, but aspiration cytology is not. In this study [4], pathologic subtype was correctly predicted in 91% by needle core biopsy. This sensitivity is relatively higher. However, the accuracy of percutaneous core biopsy depends on the type of needle used, number of cores, and study design and methods. In recent years, various new treatment strategies, including molecular-targeted therapy, are planned for patients with RCC. The accurate diagnosis of subtype is important for success of such treatment because subtype correlates with response rates for various treatments. In addition to technical improvement of image-guided biopsy, further work on diagnostic techniques and biomarkers is necessary [5]. References [1] Somani BK, Nabi G, Thorpe P, N Dow J, Swami S, McClinton S, Aberdeen Academic and Clinical Urological Surgeons (ABACUS) Group. Image-guided biopsy-diagnosed renal cell carcinoma: critical appraisal of technique and long-term follow-up. Eur Urol 2007;51: [2] Maturen KE, Nghiem HV, Caoili EM, Higgins EG, Wolf Jr JS, Wood Jr DP. Renal mass core biopsy: accuracy and impact on clinical management. AJR Am J Roentgenol 2007;188: [3] Renshaw AA, Lee KR, Madge R, Granter SR. Accuracy of fine needle aspiration in distinguishing subtypes of renal cell carcinoma. Acta Cytol 1997;41:

10 1012 european urology 53 (2008) [4] Schmidbauer J, Remzi M, Memarsadeghi M, et al. Diagnostic accuracy of computed tomography-guided percutaneous biopsy of renal masses. Eur Urol 2008;53: [5] Barocas DA, Mathew S, DelPizzo JJ, et al. Renal cell carcinoma sub-typing by histopathology and fluorescence in situ hybridization on a needle-biopsy specimen. BJU Int 2007;99: DOI: /j.eururo DOI of original article: /j.eururo