Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management

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1 Renal Mass Core Biopsy Genitourinary Imaging Original Research Katherine E. Maturen 1,2 Hanh V. Nghiem 3 Elaine M. Caoili 1 Ellen G. Higgins 1 J. Stuart Wolf, Jr. 4 David P. Wood, Jr. 4 Maturen KE, Nghiem HV, Caoili EM, Higgins EG, Wolf JS Jr, Wood DP Jr Keywords: core biopsy, kidney, renal disease, renal mass DOI: /AJR Received February 9, 2006; accepted after revision May 16, Department of Radiology, UH B1D407, University of Michigan Hospitals, Ann Arbor, MI. 2 Present address: Department of Radiology, Stanford Hospital and Clinics, 300 Pasteur Dr., H1307, Stanford, CA Address correspondence to K. E. Maturen (katematuren@yahoo.com). 3 Department of Diagnostic Radiology, William Beaumont Hospital, Royal Oak, MI. 4 Department of Surgery Urology, University of Michigan Hospitals, Ann Arbor, MI. AJR 2007; 188: X/07/ American Roentgen Ray Society Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management OBJECTIVE. The objective of our study was to determine the accuracy of imaging-guided percutaneous renal mass biopsy and its impact on clinical management. MATERIALS AND METHODS. With institutional review board approval, we retrospectively reviewed imaging-guided renal biopsies performed by radiologists at our institution between February 1999 and July Patient records, pathology reports, and imaging studies were reviewed. Concordance of biopsy diagnosis and follow-up data was assessed. Significant impact on clinical management was determined in collaboration with two experienced urologists and was defined as a change from no therapy to therapy, including surgery, tumor ablation, chemotherapy, or radiation. RESULTS. Two hundred seventy-six renal biopsies were performed during the study period. Of these, 123 were random biopsies and fine-needle technique was used for one; these 124 were excluded. One hundred fifty-two renal mass biopsies were performed using coaxial 18- gauge core needle technique in 125 patients (55 women, 70 men; average age, 60 years; range, years). There were two (1.3%) postprocedural hematomas (one [0.7%] requiring blood transfusion) and one (0.7%) delayed renal pseudoaneurysm attributed to biopsy. No tumor seeding was identified. In 85 biopsies (56%), malignant neoplasm was found, 61 biopsies (40%) yielded benign findings, and six (4%) were nondiagnostic. The sensitivity for malignancy was 97.7%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 100%. At least 92 (60.5%) biopsy results significantly impacted clinical management. CONCLUSION. Imaging-guided percutaneous core needle biopsy of renal masses is safe and highly accurate. Tissue diagnosis alters clinical decision making in a majority of the cases and may allow a number of unnecessary nephrectomies to be avoided. he accuracy of percutaneous renal mass biopsy has been widely T debated, and many urologists have concluded that the diagnostic yield is too low to warrant potential procedural complications [1 4]. Indeed, percutaneous imaging-guided fine-needle aspiration (FNA) suffered from poor sensitivity and frequent nondiagnostic results [1, 2, 4, 5]. However, researchers of several studies reported that 18-gauge core needle biopsy achieved % sensitivity for the detection of malignancy [6 9]. Methods of renal mass assessment have become an important question in the care of an increasing number of patients: Renal cell carcinoma (RCC) is among the 15 most common malignancies in both men and women and has steadily increased in incidence since 1975 [10]. Increasingly, these cancers are recognized incidentally as small (< 3 cm) masses [11]. Although advances in sonography, CT, and MRI technology allow accurate differentiation between solid and cystic lesions, the ability of imaging to differentiate benign from malignant renal masses remains limited [12 16]. Tissue diagnosis may be needed to direct therapy and potentially to avoid unnecessary nephrectomies. Meanwhile, both the reliability of percutaneous biopsy and the appropriate clinical context for the procedure remain matters of debate. Many published reports evaluate relatively small patient populations, while studies of larger populations assembled over 15- to 30- year periods at multiple institutions are limited by heterogeneity in biopsy technique and clinical follow-up [17, 18]. We report our experience in performing renal mass biopsy with specific attention to two questions: assessment of the accuracy of imaging-guided percutaneous core needle technique and whether the information provided by biopsy alters management. AJR:188, February

2 Fig year-old man with history of prostate cancer. Renal mass was detected on staging CT. Contrast-enhanced CT image obtained during biopsy with patient in prone position shows introducer needle penetrating mass. Biopsy of left renal mass revealed renal cell carcinoma. Materials and Methods Subjects Institutional review board approval was obtained for retrospective case series review of renal mass biopsies performed by the radiology crosssectional interventional service from February 1999 though July Imaging studies (including CT, MRI, and sonography), clinical notes, and laboratory and pathology data were reviewed. Biopsy results were correlated with surgical or clinical follow-up. Sensitivity and specificity of biopsy for the detection of malignancy were calculated. Procedures Before all biopsies, platelet counts were confirmed to be 50,000/mm 3 or were corrected. Coagulation status was also corrected when appropriate, with an international normalized ratio (INR) of 1.5 at the time of biopsy in all patients. Biopsies were performed with the patient under conscious sedation (IV fentanyl [ µg], midazolam [ mg], or both) except when performed as part of a combined procedure with radiofrequency ablation, for which general anesthesia was administered. Local anesthesia was administered with 1% lidocaine buffered with bicarbonate. CT or sonographic guidance was used to direct the biopsy depending on operator preference, lesion imaging characteristics, or both. Four patients received ml of iodinated contrast material IV to improve lesion conspicuity on CT. Patient position depended on the location of the mass, with biopsies performed with the patient prone (Fig. 1) or in a lateral decubitus position. Coaxial technique was uniformly implemented using a 17-gauge introducer and an 18-gauge springloaded biopsy gun (ASAP and Easy Core needles and Pinpoint introducer, Boston Scientific). The introducer remained in position while multiple passes were made with the cutting needle. Up to four cores were obtained from each tumor, with three or four cores obtained in most patients. Postbiopsy images were not routinely obtained. Samples were placed in normal saline, formalin, or both and were hand-carried to the pathology laboratory; neither a pathologist nor a cytology technician was present in the biopsy suite. Due to operator preference or because the patient was bleeding around the introducer, procoagulant agents were injected along the needle track in some patients: absorbable bovine collagen (Helitene, Integra Life Sciences) in 40 patients and absorbable pork gelatin powder (Gelfoam, Pharmacia & Upjohn) in one patient. All patients were hemodynamically monitored in the radiology recovery area for 4 hours after the procedure, and any complications were recorded. We did not routinely perform imaging to evaluate for postprocedural hematomas, but all cases of hemorrhage identified either by postprocedural imaging or by clinical signs or symptoms were included among the reported complications. Subsequent clinical notes and imaging reports were reviewed to assess for any delayed complications such as tumor seeding. Terms Definitely benign masses were those that had surgical or autopsy histologic confirmation of benignity, resolved, decreased in size on cross-sectional imaging without treatment, or were stable on cross-sectional imaging for 2 years. Probably benign masses were those that were stable on cross-sectional imaging for between 6 months and 2 years. Core needle biopsy diagnoses of oncocytoma in patients with multiple renal masses including at least one surgically proven oncocytoma were also considered probably benign. Indeterminate masses had no or insufficient follow-up to confirm benignity. Significant impact on clinical management was determined in collaboration with two urologists experienced in TABLE 1: Demographic and Clinical Information Regarding 152 Renal Masses Characteristic Value No. of patients 125 Age Mean 60 Range Sex (male:female ratio) 70:55 No. of patients who underwent repeat 27 biopsies Reason for repeat biopsy Radiofrequency ablation follow-up 20 Second mass 3 Diagnostic dilemma 3 Nondiagnostic biopsy 1 Type of tumor (no. of tumors) Solid 135 Mixed cystic solid 17 Maximum tumor diameter (cm) Mean 4.1 Range 1 13 Mass location Right kidney 70 Left kidney 81 Transplant 1 Biopsy technique No. of biopsies with CT guidance 76 No. of biopsies with sonographic 76 guidance oncology and was defined as a change between no therapy and therapy, meaning either the addition or removal of any of the following to or from the therapeutic plan: surgery, percutaneous ablation, catheterbased ablation, external beam radiation, or systemic chemotherapy. Imaging follow-up consisted of dedicated contrast-enhanced CT or MRI of the abdomen. Results Subjects Two hundred seventy-six renal biopsies were performed during the study period. Of these, 123 were random biopsies performed to assess rejection in transplant kidneys or to determine the cause of renal failure in native kidneys and were excluded. In one patient, FNA technique was used and that patient was excluded. The remaining 152 renal mass biopsies were performed using coaxial 18- gauge core needle technique; patient and mass characteristics are summarized in Table 1. All but one renal mass biopsied 564 AJR:188, February 2007

3 Renal Mass Core Biopsy Fig year-old woman with history of renal transplant for lupus nephritis. Coronal contrast-enhanced T1-weighted spoiled gradient-recalled acquisition in steady state (SPGR) image shows hypointense mass (arrow) in interpolar region of right lower quadrant transplant kidney. Biopsy revealed posttransplantation lymphoproliferative disorder. TABLE 2: Results of 152 Renal Mass Biopsies No. of Biopsy Result Cases Angiomyolipoma 4 Benign parenchyma 13 Carcinoma not otherwise specified 9 Infarct 1 Infection 2 Inflammatory 6 Lymphoma 10 Mixed epithelial and stromal tumor 2 Metastases 5 Nondiagnostic 6 Oncocytoma 16 No viable tumor after 17 radiofrequency ablation Renal cell carcinoma 59 Sarcoma 2 Total 152 (Fig. 2) arose in native kidneys. Three biopsies were performed for diagnosis of ill-defined infiltrative processes (Fig. 3). Two patients (1.3%) had postprocedural hematomas: One was managed conservatively and the other required transfusion of 4 U of packed RBCs. One of these patients had received Helitene in the needle track, and the other had not received a procoagulant injection. The final diagnoses were RCC and interstitial fibrosis, respectively. Regarding other immediate complications, one patient had transient difficulty in urination that resolved after bladder catheterization and saline flushes. One patient had postprocedural lightheadedness that resolved without intervention. Regarding long-term complications, one patient (0.7%) with biopsy diagnosis of oncocytoma presented with retroperitoneal bleeding 3 months after biopsy. Angiography revealed a pseudoaneurysm, and endovascular tumor embolization was performed. (We have previously reported the same patient in a smaller review of our experience with sonographic guidance [19].) No evidence of tumor seeding or of another delayed complication was identified after detailed record review. The average imaging follow-up was 9.7 months (range, 0 60 months). Sensitivity for Detection of Malignancy Of 152 biopsies, 85 (56%) showed malignant neoplasm, 61 (40%) yielded benign findings, and six (4%) were nondiagnostic. The benign biopsies included 22 (14.5%) benign neoplasms and 39 (25.7%) nonneoplastic results. The biopsy results are detailed in Table 2. Fuhrman s nuclear grade in RCC is not routinely reported by our pathology department. Fig year-old man with enlarged cervical lymph nodes. Contrast-enhanced CT image reveals infiltrative mass (arrow) replacing right kidney and extending into perirenal fat. Biopsy revealed large B-cell lymphoma. Eighty-seven masses were confirmed malignant by surgical excision or natural history. Of these, 85 had biopsies positive for malignancy and two had nondiagnostic biopsies. Thus, to our knowledge, the sensitivity for detection of malignancy was 97.7%, given the two nondiagnostic biopsies of malignant masses. Because no malignant biopsy results have been identified as false-positives, both specificity and positive predictive value are 100%. Of the 61 (40%) benign biopsy results, 19 (12.5% of 152 total) were definitely benign, 28 (18.4%) were probably benign, and 14 (9%) were indeterminate on review of follow-up data. None of the benign biopsies has subsequently been proven malignant. The negative predictive value of benign biopsy results to exclude malignancy is considered to be 100% (regarding nondiagnostic biopsies as a separate group). The six (4%) nondiagnostic biopsies were performed on renal masses ranging from 2 to 12 cm in size, with an average size of 6.4 cm. Four were performed under sonographic guidance and two under CT guidance. No specific difficulties were noted by the operators at the time of biopsies. Two were solid (Fig. 4), two were cystic, and two were mixed. Two were subsequently shown to be malignant; one, definitely benign; one, probably benign; and two, indeterminate. AJR:188, February

4 Fig year-old woman with no history of malignancy. A, Unenhanced CT image obtained with patient in prone position depicts low-attenuation right renal mass (arrow). B, Biopsy image shows needle entering same region as that shown in A. Biopsy was nondiagnostic. Subsequent nephrectomy revealed renal cell carcinoma. Known extrarenal malignancies (n = 40) Benign result (n = 17) Infection, inflammation, or normal parenchyma (n = 9) Oncocytoma (n = 4) Mixed epithelial and stromal tumor (n = 2) No viable tumor after RFA (n = 2) Malignant result (n = 23) RCC (n = 10) 152 renal masses Solid organ metastasis (n = 7) Lymphoma (n = 6) A No known extrarenal malignancies (n = 112) Post RFA (n = 18) Nondiagnostic (n = 1) Diagnostic (n = 1) Other masses (n = 94) RCC (n = 48) Benign result (n = 28) Metastasis from occult extrarenal malignancy (n = 7) Carcinoma NOS (n = 6) Nondiagnostic (n = 5) Impact on Clinical Management Forty patients (26%) had known extrarenal malignancies at the time of biopsy (Fig. 5). Biopsy was considered to significantly impact clinical management in all 40 of these patients because proof of metastatic disease or of a second primary cancer would alter therapy. Among these, 23 had biopsies positive for malignancy, including RCC (n = 10) (Fig. 6), solid organ metastases (n =7), and lymphoma (n = 6) (Fig. 7). Seventeen had benign biopsies, including oncocytoma (n = 4) (Fig. 8); mixed epithelial and stromal tumor (n = 2); infectious, inflammatory, or normal parenchyma (n = 9) (Fig. 9); and no viable tumor after radiofrequency ablation (n =2). One hundred twelve patients (74%) had no known extrarenal malignancy at the time of biopsy. Among these, 18 were undergoing repeat biopsy after radiofrequency ablation, of whom one had residual RCC, one had residual oncocytoma, and one had a nondiagnostic biopsy. It should be noted that the patient with residual RCC had a biopsy report indicating a few residual nests of tumor cells only. Histologic diagnosis was made without the use of nicotinamide adenine dinucleotide (NADH) stain, which later became customary for our evaluation of patients after radiofrequency ablation [20]. Biopsy was considered to have affected management of the 17 radiofrequency ablation patients who had diagnostic biopsies because additional ablation sessions or potential surgery hinged on the biopsy result. In the remaining 94 patients with no history of malignancy or radiofrequency ablation, RCC Fig. 5 Diagram shows clinical categorization of 152 renal masses. Gray boxes indicate groups with biopsy results impacting clinical management. RFA = radiofrequency ablation, RCC = renal cell carcinoma, NOS = not otherwise specified. was the anticipated diagnosis. Five of these patients had nondiagnostic biopsies, which did not impact management. Twenty-eight had benign biopsies, including angiomyolipomas (n =4) (Fig. 10) and oncocytomas (n = 11) among other nonneoplastic lesions such as sarcoidosis (Fig. 11). These 28 patients clearly had a change in management due to biopsy results because the diagnostic alternative was nephrectomy. The remaining 61 biopsy results confirmed malignancy. These included RCCs (n = 48) and carcinoma not otherwise specified (NOS) (n =6) that were not considered to affect management because they were among the expected outcomes. One patient with a mass that was included in the RCC group had a biopsy result showing oncocytic neoplasm with suspicious features highly concerning for chromophobe RCC ; RCC was B 566 AJR:188, February 2007

5 Renal Mass Core Biopsy Fig year-old woman with history of non small cell lung cancer. Contrastenhanced CT image shows large right renal mass with central low attenuation. Biopsy revealed renal cell carcinoma. Fig year-old man with history of prostate cancer and lymphoma. Coronal oblique reformatted image from excretory phase of contrast-enhanced CT examination shows infiltrative soft-tissue mass surrounding right renal pelvis and proximal ureter (arrow). Biopsy of renal pelvis mass revealed recurrent large B-cell lymphoma. Large upper pole cyst (arrowhead) is incidentally noted. Fig year-old woman with history of colon cancer. Contrastenhanced CT image reveals exophytic mass (arrow) arising from malrotated left kidney. Comparison with unenhanced images (not shown) confirmed enhancement. Biopsy revealed oncocytoma. Mass has been stable in size for 5 years. confirmed at nephrectomy. However, seven occult malignancies including lymphoma (n =4), sarcoma (n = 2), and melanoma (n = 1) (Fig. 12) were also discovered in this group. Biopsy results clearly affected management for these seven patients, for whom inappropriate treatments were avoided by preoperative histologic diagnosis. Thus, of 152 masses biopsied, 92 (60.5%) biopsy results significantly impacted clinical management, when significant impact is defined as a change between no therapy and therapy, including surgery, percutaneous ablation, transcatheter ablation, external beam radiation, or systemic chemotherapy. Discussion We found that percutaneous core needle biopsy of renal masses was 97.7% sensitive and 100% specific for the detection of malignancy. This finding is concordant with recent reports of % sensitivity using core biopsy [5, 18, 21 23]. The high sensitivity for the detection of malignancy in the current study is in contrast to results of older reports of FNA that noted poor sensitivity for the detection of malignancy (as low as 50%) and a high rate of nondiagnostic biopsies (up to 33%) [1, 2, 4, 5, 24]. We suggest this increase in sensitivity is due to the larger volume of tissue obtained with 18- gauge core biopsy needles, as has been noted in other studies [5]. At least two groups have examined core biopsies performed ex situ on surgical specimens of kidneys containing masses. Dechet et al. [3] biopsied 100 masses at total or partial nephrectomy using 18-gauge core biopsy technique, with a 31% nondiagnostic rate from biopsy. Among the diagnostic specimens, the sensitivity for the detection of malignancy was just over 80%. This finding is significantly worse than that of the current study and most reports of core needle technique in situ [6 9]. It is difficult to understand the low diagnostic yield given direct visualization and palpation of the tumors. It is possible that imaging provides more accurate assessment of lesion characteristics, allowing the operator to target nodular areas and avoid necrotic areas, or that inexperience with percutaneous technique resulted in poor tissue yield. Whatever the cause, this discrepancy underscores the difficulty in extrapolating ex situ biopsy results to percutaneous in situ technique, although the findings are rather the reverse of what might have been expected. By contrast, AJR:188, February

6 Fig year-old man with acute lymphocytic leukemia. Contrast-enhanced CT image shows low-attenuation left renal mass (arrow). Biopsy revealed severe diffuse tubular injury/necrosis; focal viral cytopathic changes suggesting cytomegalovirus infection, no evidence of recurrent leukemia. Fig year-old man with single transient episode of acute renal failure. Subsequent contrast-enhanced CT image reveals multiple tiny bilateral lowattenuation renal masses. Biopsy was requested to evaluate lymphoma versus multiple renal cell carcinomas potentially related to von Hippel-Lindau syndrome. Biopsy revealed sarcoidosis. Wunderlich et al. [25] biopsied 50 masses using apparently identical ex situ technique and found 98% sensitivity for the detection or exclusion of malignancy. We performed six (4%) nondiagnostic biopsies. Again, this is in keeping with reports of core technique and is better than reports of FNA. Although we did not identify specific imaging features predisposing to nondiagnostic biopsy, some authors have noted diminished sensitivity for the detection of malignancy and loss of accuracy in tumor grading in small lesions ( 3 4 cm) [6, 9, 22] and in predominantly cystic lesions [17]. We did not find significant differences in biopsy accuracy arising from mode of imaging guidance (CT or Fig year-old woman with weight loss and questionable lytic lesion in spine (arrow). Contrast-enhanced CT image depicts right renal mass (arrowhead) containing several pixels measuring 0 H combined with enhancing soft-tissue components. Biopsy revealed benign angiomyolipoma. Fig year-old man with no history of malignancy. Contrast-enhanced CT image shows low-attenuation right posterior renal mass (arrow). Biopsy revealed metastatic melanoma. sonography). A few reports have emphasized the utility of sonographic guidance [5, 19] and potential technical difficulties of CT guidance [6], but no direct comparison of these methods has been undertaken, to our knowledge. Most authors appear to select imaging guidance on the basis of the operator s preference and the imaging features of individual masses. 568 AJR:188, February 2007

7 Renal Mass Core Biopsy Two (1.3%) or our patients experienced immediate postprocedural hemorrhages that did not affect long-term outcomes. This finding is comparable to those of prior studies reporting occasional subcapsular hematomas [2, 5, 6, 21] that rarely required transfusion and had no long-term effect on patient outcome, but many authors do not report complications. Our standard procedure is 4 hours of observation after biopsy without further imaging unless signs or symptoms suggest hemorrhage. Routine postprocedure or delayed imaging might reveal higher rates of hemorrhage, but without compromise of hemodynamic stability the clinical significance is questionable. Regarding long-term complications, one (0.7%) of the patients in our study experienced delayed retroperitoneal hemorrhage due to arterial pseudoaneurysm formation and rupture. Pseudoaneurysm formation is a recognized complication of biopsy [26, 27], although the incidence is unknown because most are probably asymptomatic. We identified no other long-term complications specifically, no tumor seeding. None of the cited studies describe evidence of seeding, whereas some authors with extensive longitudinal follow-up [7, 8, 18, 28] specifically note the absence of seeding. Some speculate that their routine use of coaxial biopsy technique may aid in preventing RCC seeding [7, 18], which we have also noted in hepatocellular carcinoma [29]. However, seeding in slow-growing tumors such as RCC may be temporally remote from the biopsy and attention to the body wall on follow-up imaging is certainly appropriate. In the end, biopsy techniques and accuracy rates are only as significant as their impact on clinical management. We found that of 152 biopsies, just over 60% significantly impacted clinical management. Several groups have attempted to quantify the impact on patient management with roughly similar results [6, 17, 21]. Ours is likely a conservative estimate because the 59 patients with RCC may have had subtler changes in management depending on biopsy histology such as partial versus total nephrectomy or laparoscopic versus open surgical approach. We suggest that 60% alteration in management represents an important and substantive change in the care of many patients, particularly those who avoid nephrectomy by means of biopsy diagnosis. In particular, biopsy data were essential to the appropriate care of 35 patients without extrarenal malignancy who were thought to have RCC but found to have benign masses (n =28) or malignancies other than RCC (n =7). Unfortunately, our data do not allow us to specifically predict which patients will be among the 60% with altered management. We summarize the clinical indications that were of particular importance in our study and in the recent literature [4, 6, 22, 24, 30] in Appendix 1, noting however that no decrease in sensitivity of biopsy was noted in other patient groups. The nonstandardized clinical follow-up and absence of surgical confirmation of benignity in some of the benign biopsies are the major limitations of the study. We did not include these as false-negative biopsies because we considered it unlikely that all were in fact undiagnosed malignancies. Some uncertainty may be inherent because the biopsy diagnosis was often used to avoid the nephrectomies that might have confirmed benignity. For example, 16 biopsies had a benign result of oncocytoma. Among these, only one biopsy result was confirmed at resection, four patients had prior surgically confirmed oncocytomas, eight masses were definitely benign, and three masses were probably benign or indeterminate by imaging follow-up. This is a benign tumor that can be diagnosed percutaneously [20, 31]; thus, 15 additional nephrectomies would have been needless. To perfectly quantify sensitivity in our study, it would be necessary to resect all 152 masses, which would be unethical in cases in which the urologist s judgment and a tissue diagnosis of benignity coincide. Other limitations include the absence of tumor grading information in RCC and specific histologic confirmation in some of the biopsies revealing inflammation or infection, which were treated without surgical excision. Finally, we are unable to comment on specific imaging features of benign and malignant lesions in our population because of the heterogeneity of the prebiopsy imaging evaluation in this retrospective study. A prospective approach with dedicated imaging protocols might enable biopsy recommendations based on specific imaging features. In summary, we found that imaging-guided percutaneous renal mass biopsy performed with an 18-gauge coaxial core needle technique is highly sensitive for the detection of malignancy, with relatively few nondiagnostic biopsies and very few procedure-related complications. Biopsy results significantly affected clinical management meaning a change between therapy and no therapy in a majority of the patients. We conclude that percutaneous core biopsy is a safe and accurate means of characterizing renal masses that may allow a number of unnecessary nephrectomies to be avoided. References 1. Brierly RD, Thomas PJ, Harrison NW, Flectcher MS, Nawrocki JD, Ashton-Key M. Evaluation of fine-needle aspiration cytology for renal masses. BJU Int 2000; 85: Campbell SC, Novick AC, Herts B, et al. Prospective evaluation of fine needle aspiration of small, solid renal masses: accuracy and morbidity. Urology 1997; 50: Dechet CB, Zincke H, Sebo TJ, et al. 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