Posterior retroperitoneoscopic partial nephrectomy using microwave tissue coagulator for small renal tumors

BACKGROUND AND PURPOSE: Laparoscopic partial nephrectomy remains surgically challenging because of the potential for excessive blood loss, infection, and the development of urinary fistulas. In addition, posterior retroperitoneoscopic partial nephrectomy is not popular because of the limited space for surgical manipulation. We evaluated the usefulness of a microwave tissue coagulator in posterior retroperitoneoscopic partial nephrectomy for small posterior renal tumor. PATIENTS AND METHODS: Posterior retroperitoneoscopic partial nephrectomy was performed without renal pedicle clamping using a microwave tissue coagulator in six patients with small posterior renal tumors. RESULTS: The mean operative time was 136 minutes (range 78-180 minutes), and the blood loss was <20 mL. No serious operative complications occurred, and there was no significant deterioration of renal function. CONCLUSION: Posterior retroperitoneoscopic partial nephrectomy using a microwave tissue coagulator can be a safe and less invasive method for the treatment of small posterior renal tumors.     

Retroperitoneoscopic nephron-sparing surgery of renal tumor using a microwave tissue coagulator without renal ischemia: comparison with open procedure

PURPOSE: It is ideal to use not a transperitoneal but a retroperitoneal approach for both open and endoscopic partial nephrectomy. We compared the results of retroperitoneoscopic nephron-sparing surgery for small renal tumors using a microwave tissue coagulator without renal pedicle clamping with those of a retroperitoneal open procedure. PATIENTS AND METHODS: Between 1996 and 2002, eight patients with small renal tumors underwent retroperitoneoscopic partial nephrectomy without renal ischemia, and nine patients with small renal tumors underwent open partial nephrectomy via a retroperitoneal approach. Both groups were operated on using a microwave tissue coagulator. RESULTS: Retroperitoneoscopic partial nephrectomy without renal ischemia was performed without any major or minor complications in any patient. The mean operation time for retroperitoneoscopic surgery was significantly longer than that for open partial nephrectomy (221.9 minutes v 145.9 minutes; P = 0.0004). However, the mean estimated blood loss for retroperitoneoscopic surgery was less than that for open partial nephrectomy (137.5 mL v 334.8 mL; P = 0.012). In addition, the retroperitoneoscopic group seemed to recover more rapidly than the open surgery group. CONCLUSIONS: Retroperitoneoscopic nephron-sparing surgery of small renal tumors using a microwave tissue coagulator without renal ischemia is feasible as minimally invasive procedure. It results in saving renal function, minimal blood loss, and rapid recovery.     

Non-ischemic partial nephrectomy using microwave tissue coagulator

PURPOSE: The indications and the safety of non-ischemic partial nephrectomy using a microwave tissue coagulator were studied. MATERIALS AND METHODS: Non-ischemic partial nephrectomy was performed on 17 kidneys of 16 patients using a microwave tissue coagulator. The diagnosis was renal tumor and renal stones in eleven and five patients, respectively. Renal tumors were less than 4 centimeters in diameter, while the stones were associated with a caliceal diverticulum or secondary cortical atrophy. Excision of the tumors was done via the retroperitoneal approach through an oblique lumbar incision. The needle of the microwave tissue coagulator was inserted around the tumor (stone) 10 to 20 times, and the coagulator was activated. Then the tumor (stone) was excised with a sharp knife or scissors. Patients were encouraged to walk on the first postoperative day. RESULTS: Vascular clamping was necessary in one patient to reduce bleeding. Nephrectomy was done after partial nephrectomy in one patient because it was difficult to close the urinary collecting system after it was widely exposed. Although urine leakage was seen postoperatively in two patients, it ceased spontaneously at 14 and 23 days after surgery. Postoperative complications developed in one of seven patients (14%) with protruding renal tumor, in three of five patients (60%) with non-protruding renal tumor and in two patients with renal stone. Allogenic or autologous blood transfusion was not necessary, nor was any bleeding noticed post-operatively. In one patient, atrophy of the renal parenchyma occurred gradually after surgery and function was eventually lost. However, renal function was well preserved and recurrence of the problem was not observed in the other 15 patients, excluding one who died of esophageal cancer. CONCLUSIONS: The microwave tissue coagulator is a useful surgical instrument for non-ischemic partial nephrectomy, not only in patients with renal tumors but also in patients with complicated kidney stones. However, non-protruding renal tumor in a patient with solitary kidney should be avoided for this surgery. Thermal injury to the renal parenchyma or large vessels should be avoided and urine leakage from the collecting system should be meticulously treated during the operation.     

Impact of microwave tissue coagulation during laparoscopic partial nephrectomy on postoperative renal function

Laparoscopic partial nephrectomy for small renal tumors has been performed with increasing frequency over the past few years. We prospectively evaluated preoperative and postoperative differential renal function in patients with functioning contralateral kidneys who underwent laparoscopic partial nephrectomy using a microwave tissue coagulator without hilar clamping. Seven patients (five men and two women) in this prospective protocol underwent laparoscopic partial nephrectomy for exophytic tumors using a microwave tissue coagulator when the tumor was 2 cm or less in diameter. Renal scanning with ⁹⁹technetium-labeled diethylenetetraminepentaacetic-acid scan was performed preoperatively and postoperatively at 7 days and 6 months after surgery in all patients. The mean tumor size and surgical duration were 17.0 ± 2.3 mm and 161.1 ± 20.5 min, respectively. Intraoperative blood loss was 35.6 ± 40.7 ml. The preoperative glomerular filtration rate (GFR) and differential split renal function (SF) in the affected kidney were 45.7 ± 12.8 ml/min and 50.5 ± 3.3%, respectively. On postoperative day 7 and at 6 months, GFR and SF in the affected kidney were 36.2 ± 9.0 and 36.8 ± 10.9 ml/min and 44.3 ± 4.1 and 45.0 ± 5.1%, respectively. No postoperative complications occurred. Laparoscopic nonischemic partial nephrectomy using a microwave tissue coagulator has the advantage of technical ease and adequate hemostasis. However, its indication should be restricted to small exophytic renal tumors due to the expected collateral damage causing renal impairment.     

Laparoscopic partial nephrectomy using microwave tissue coagulator for small renal tumors: usefulness and complications

OBJECTIVES: We evaluated the usefulness and complications of laparoscopic partial nephrectomy for small renal tumors using a microwave tissue coagulator without renal pedicle clamping. METHODS: Between September 1999 and March 2003, 19 patients with small renal tumors 11 to 45 mm in diameter underwent laparoscopic partial nephrectomy without renal ischemia. RESULTS: Six and 13 patients were treated by the transperitoneal and retroperitoneal approaches, respectively. Excluding a case with open conversion due to dense perirenal adhesions, 18 patients successfully underwent laparoscopic procedures. The mean operative time was 240 minutes with minimal blood loss in 14 patients and 100 to 400 ml in 4. In a patient, frozen sections revealed a positive surgical margin and additional resection was performed. Postoperative complications included extended urine leakage for 14 days, arteriovenous fistula and almost total loss of renal function, respectively, in a patient. With the median follow-up of 19 months, no patients showed local recurrence or distant metastasis by CT scan. CONCLUSIONS: Laparoscopic non-ischemic partial nephrectomy using a microwave tissue coagulator may be useful for treating small renal tumors because it does not require advanced laparoscopic skill. However, the indication of this procedure should be highly selective in order to minimize serious complications secondary to unexpected collateral damage to surrounding structures.     

Renal-tissue damage induced by laparoscopic partial nephrectomy using microwave tissue coagulator

BACKGROUND AND PURPOSE: The microwave coagulator is a useful instrument that enables surgeons to perform partial nephrectomy without vascular clamping. The extent of postoperative thermal damage in surgically spared renal tissue has not been well examined. The present study was conducted to evaluate the tissue damage caused by microwave coagulation in laparoscopic partial nephrectomy (LPN) for small renal tumors. MATERIALS AND METHODS: Seven cases of LPN with a microwave tissue coagulator were entered in the present study. The median tumor diameter was 1.5 cm, and the median size of the resected specimen was 2.2 cm. Postoperative tissue damage was evaluated by contrast-enhanced CT 1 month after surgery. Surgically spared renal-tissue volume and functioning renal-tissue volume were estimated from the images by NIH Image 1.62 software. RESULTS: Postoperative CT revealed unenhanced renal tissue adjacent to the surgical margin. The median estimated volumes of surgically spared and functioning renal tissue were 96.1% (range 74.3%-99.8%) and 88.4% (range 68.0%-92.7%) of preoperative normal renal tissue, respectively. The percentile volume of functioning to surgically spared renal tissue ranged from 89.9% to 96.0% (median 92.8%). CONCLUSIONS: The microwave coagulator enables us to carry out partial nephrectomy without vascular clamping. Although 96% of normal renal tissue was surgically spared, 4% to 10% of this tissue was nonfunctioning as a result of microwave-induced thermal damage.     

Retroperitoneoscopic partial nephrectomy for renal cell carcinoma: our initial experience and review of the literature

PURPOSE: We report our initial experiences of retroperitoneoscopic partial nephrectomy for renal cell carcinoma. MATERIALS AND METHODS: From April 2002 to October 2003, we performed 11 retroperitoneoscopic partial nephrectomy for renal cell carcinoma. Our indication was T1N0M0 renal tumors which sizes were about 4 cm or less and were exophytic and were not situated at the renal hilum. First we inserted single J catheter to the renal pelvis cystoscopically. under fluoroscopic guidance. Next 4 trocars were set at pneumoretroperitoneum and the renal artery and vein were clamped individually after cold saline was circulated from the single J catheter. Renal parenchyma was sharply cut with scissors and vessels were coagulated with bipolar coagulator. When renal collecting system was opened, cariceal suture repair was performed. We used the microwave tissue coagulator without clamping the renal pedicle when the tumor was 2 cm or less in diameter and the distance from the tumor edge to the renal collecting system was more than 1cm. RESULTS: In 9 cases renal pedicles were clamped and in 2 cases were not. Mean tumor size was 27.5 +/- 8.9 mm and mean operative time was 350 +/- 92 minutes and mean estimated blood loss was 743 +/- 998 ml, and mean warm ischemic time was 70 +/- 30 minutes. In one case bleeding from cut surface was uncontrollable, so open conversion was needed. In this case the renal artery and vein were clamed but another artery exited. The surgical margins were all negative, and no other complications were happened. Post operative serum creatinine raised soon after the operation but finally downed, and the mean up level was 0.07 ng/ml only. But RI examination revealed the residual renal damages were in proportioned to the warm ischemic times. During a mean followup of 8 months no patients has had local recurrence or metastatic disease. CONCLUSIONS: Retroperitoneoscopic partial nephrectomy for renal cell carcinoma is effective for select patients. But better cooling method and earlier suture technique and more long follow-up periods will be necessary for establishment.     

Application of the microwave tissue coagulator: is it beneficial to partial nephrectomy?

BACKGROUND/AIM: The indications of partial nephrectomy have expanded after the introduction of new techniques for preventing excessive blood loss and avoiding deterioration of the renal function after clamping the renal pedicle. We present our clinical experience of partial nephrectomy for renal tumors using a microwave tissue coagulator. PATIENTS AND METHODS: Between April 1996 and January 2000, 34 patients underwent open partial nephrectomies in the Kobe City General Hospital. The microwave tissue coagulator was used for resection of the renal parenchyma, but in deeper lesions a sharp dissection was performed. Twenty-two patients (groups 1 and 2) underwent partial nephrectomy without vascular control (14 renal pedicles were not disturbed in group 1 patients, and 8 renal pedicles were dissected but not clamped in group 2 patients). Another 12 patients (group 3) underwent vascular control with ligation of the tumor-feeding segmental arteries before parenchymal resection. The patients of group 1 underwent wedge resections, while those of groups 2 and 3 underwent segmental or transverse partial nephrectomies. RESULTS: Complete tumor resection was done in all 34 patients. In group 1, the microwave tissue coagulator was very effective to control the blood loss (mean 330 ml). In larger resections, this method only was inadequate to control the blood loss (mean 489 ml in group 2), so that we needed vascular control. However, despite vascular control, mean blood losses of about 943 ml because of deeper venous bleeding occurred in group 3, and, moreover, postoperative renal infarctions occurred in 2 patients. Other complications were urinary fistula formation in 16 patients (47%) and renal pelvic stenoses in 2 patients (5.8%). All of the urinary fistulas were easily repaired by simple suturing intraoperatively. CONCLUSIONS: Especially in wedge resection, the microwave tissue coagulator achieved safe resection without vascular control which differs from other new techniques. However, in larger resections, a combination with other techniques may be necessary to decrease blood loss and the rate of complications.     

Partial nephrectomy using microwave tissue coagulator--application for laparoscopic operation

We report our clinical findings on 12 tumors (11 patients) successfully resected by partial nephrectomy with a microwave tissue coagulator (MTC) without renal pedicle clamping, including laparoscopic operation in 4 patients. All patients presented with a renal tumor detected incidentally by ultrasonography or computed tomography. The mean size of renal tumor was 1.9 (range 0.8-3.4) cm. Pathological diagnosis was renal cell carcinoma in 9 tumors and hemorrhagic cyst in 3 tumors. Mean operative time was 249 minutes. Mean blood loss was 183 ml in cases with a laparoscopic operation, that was statistically less than 486 ml in cases with an open operation (p<0.05), and 376 ml in all cases. There was no significant change in the creatinine clearance of cases with laparoscopic operation, compared with that of cases with an open operation. There were no other serious complications postoperatively. These findings suggested that partial nephrectomy with the MTC can be safely and successfully carried out while sparing renal function. Moreover, partial nephrectomy with the MTC for a laparoscopic operation may provide these patients with more benefits.     

Partial nephrectomy for renal cell carcinoma using a microwave tissue coagulator--postoperative recurrence and renal function

Nowadays, partial nephrectomy is often selected for treatment of small renal cell carcinoma (RCC) because T1a RCC shows a favorable prognosis with a 5-year overall-survival rate exceeding 90%. To determine the methodological usefulness and treatment outcome of partial nephrectomy using microwave tissue coagulator (MTC), we evaluated our series of 121 patients (124 kidneys) with T1 RCC who underwent this procedure. Ninety-nine patients were elective and 22 patients were imperative cases. This procedure was indicated for asymptomatic solitary RCC; < or =4 cm in diameter in elective cases or < or =5 cm in imperative cases, expanding outward with a clear capsule, and showing neither renal pelvis nor renal sinus invasion. The median operation time was 150 minutes and the median blood loss was 217 ml. Eight patients needed transfusion, and conservative therapy cured 4 patients of postoperative urine leakage successfully. Three patients underwent early secondary nephrectomy due to multiple RCCs, invasive spindle cell carcinoma, or prolongation of urine leakage. No significant deterioration of renal function by creatinine clearance (Ccr) was observed, and postoperative Ccr could be precisely predicted from preoperative serum creatinine value and the renal parenchymal volume estimated with 3-dimensinal image reconstruction. Five-year overall-survival rate was 91% at the mean follow-up of up to 37.9 months and 107 patients were alive without disease. One patient showed local recurrence 2 years later and underwent radical nephrectomy. We believe that non-ischemic partial nephrectmy using MTC is a simple and reliable nephron-sparing surgery for small RCC in respect of postoperative recurrence and preservation of renal function.     

Laparoscopic partial nephrectomy: the European experience.

Laparoscopic partial nephrectomy is technically difficult but oncologically effective. The operation should be performed in centers with expertise. Hemostasis can be achieved using bipolar coagulation and fibrin glue-coated cellulose. Further studies will determine whether less invasive alternatives (focused ultrasound, cryotherapy) will meet the high standard of open (or laparoscopic) nephron-sparing surgery for small renal cell carcinoma.CommentaryThe technique of laparoscopic partial nephrectomy for the treatment of renal cell carcinoma (RCC) is in its very early stages. The cumulative experience reported in the literature comprises fewer than 100 cases and these have been confounded by a lack of standardized technique and variable experience. There has been difficulty in reproducing the essential elements of open partial nephrectomy using contemporary laparoscopic instrumentation. In this large multicenter European study, hemostasis was achieved with bipolar coagulation and fibrin-coated cellulose. Notwithstanding that case selection was limited to very small (≤3 cm) peripheral renal tumors, the morbidity of partial nephrectomy in this study was greater than that of open partial nephrectomy for small peripheral tumors.At the Cleveland Clinic, we have recently developed a technique for laparoscopic partial nephrectomy which duplicates established open surgical principles. The key technical steps in this approach include:Since August 1999, this technique has been used to perform laparoscopic partial nephrectomy in 36 patients with small, exophytic renal tumors. Mean tumor size was 2.9 cm (range 1.4–7.0 cm). The operation was successful in all cases without any open conversions. Mean operative time was 2.9 h, warm ischemia time was 20 min and blood loss was 237 ml. Formal calyceal suture repair was performed in 7 patients. Mean hospital stay was 1.7 days. The final pathology revealed renal cell carcinoma in 20 patients and other tumors in the remainder. All margins of resection were negative for tumor.Our initial experience suggests that laparoscopic partial nephrectomy can be performed for small exophytic renal tumors with adherence to established principles and techniques of the open surgical approach and with significant benefits for the patient.Andrew C. Novick, M.D.     

Enucleation of renal tumor using a microwave tissue coagulator]

We report our clinical findings on 7 tumors in 5 patients who underwent successful enucleation of renal tumor with a microwave tissue coagulator. All patients presented with incidentally-found renal tumor on ultrasonography or computed tomography. One patient had bilateral renal tumors. The mean size of the renal tumor was 2.5 cm (Range 1.0-5.2 cm). One patient had a tumor larger than 5 cm, and was found to have renal insufficiency preoperatively. Four cases were clinically diagnosed as T1aN0M0. In all patients, the renal tumor was enucleated with a microwave tissue coagulator successfully without renal pedicle clamping. The mean operative time and blood loss were 241 minutes and 788 ml, respectively. The pathological diagnosis was renal cell carcinoma in all cases. Although 2 patients had preoperative renal insufficiency, there were no serious postoperative complications and no evidence of loss of renal function as a result of this operation. Our findings suggest that renal tumors can be enucleated with a microwave tissue coagulator safely and successfully without damaging renal function.     

后腹腔镜手术治疗肾脏肿瘤5例报告

目的：探讨后腹腔镜肿瘤剜除术和肾部分切除术治疗肾脏肿瘤的应用价值。方法：采用后腹腔镜经后腹腔途径对5例肾肿瘤患者分别行肿瘤剜除术和肾部分切除术，并观察手术时间，术中出血量，术后住院天数和术中术后并发症及手术效果。结果：5例手术全部获得成功，平均手术时间为87min，平均出血量55ml，平均术后住院时间为5．8d，手术效果好，无并发症。结论：该术式肿瘤切除精确彻底，创伤小，出血少，恢复快，有推广应用价值。     

Laparoscopic total and partial nephrectomy

Laparoscopic radical nephrectomy has established its role as a standard of care for the management of renal neoplasms. Long term follow-up has demonstrated laparoscopic radical nephrectomy has shorter patient hospitalization and effective cancer control, with no significant difference in survival compared with open radical nephrectomy. For renal masses less than 4cm, partial nephrectomy is indicated for patients with a solitary kidney or who demonstrate impairment of contralateral renal function. The major technical issue for success of laparoscopic partial nephrectomy is bleeding control and several techniques have been developed to achieve better hemostatic control. Development of new laparoscopic techniques for partial nephrectomy can be divided into 2 categories: hilar control and warm ischemia vs. no hilar control. Development of a laparoscopic Satinsky clamp has achieved en bloc control of the renal hilum in order to allow cold knife excision of the mass, with laparoscopic repair of the collecting system, if needed. Combination of laparoscopic partial nephrectomy with ablative techniques has achieved successful excision of renal masses with adequate hemostasis without hilar clamping. Other techniques without hilar control have been investigated and included the use of a microwave tissue coagulator. In conclusion, laparoscopic radical nephrectomy for renal cell carcinoma has clearly demonstrated low morbidity and equivalent cancer control. The rates for local recurrences and metastatic spread are low and actuarial survival high. Furthermore, laparoscopic partial nephrectomy has demonstrated to be technically feasible, with low morbidity. With short term outcomes demonstrating laparoscopic partial nephrectomy as an efficacious procedure, the role of laparoscopic partial nephrectomy should continue to increase.     

Partial nephrectomy using a microwave tissue coagulator for bilateral renal cell carcinomas: a case report

We report a case of bilateral renal cell carcinomas in a 56-year-old male treated by partial nephrectomy at the same time using a microwave tissue coagulator technique. The patient did not need dialysis after the operation because we did not need to sacrifice the artery feeding to normal renal tissue during the operation. This technique has advantages of nephron sparing without occlusion of the renal artery, and decreased operation time and blood loss.     

Retroperitoneal laparoscopic wedge resection for small renal tumor using microwave tissue coagulator

A patient with a small renal tumor underwent a successful retroperitoneal laparoscopic wedge resection using a microwave tissue coagulator without renal pedicle clamping or surface cooling. There were no postoperative complications, and renal function was well preserved. This minimally invasive procedure may be useful for treating small renal tumors.     

LAPAROSCOPIC NEPHRON SPARING SURGERY FOR SMALL RENAL CELL CARCINOMA

Purpose

In recent years the detection rate for small renal tumors has increased due to the widespread use of advanced diagnostic imaging techniques, which in turn has increased the need for nephron sparing surgery. We investigate whether laparoscopic surgery is a suitable approach to partial resection of small renal tumors.

Materials and Methods

Between June 1994 and October 1996, 7 patients underwent laparoscopic wedge resection of the kidney for renal tumors up to 2 cm. in diameter. Hemostasis was achieved mainly by bipolar coagulation. In addition, the resection surface was cauterized with an argon beam coagulator and then sealed with fibrin glue. In 1 procedure a novel ultrasonic dissector was tested.

Results

All procedures could be completed as planned. The only intraoperative complication was a pneumothorax that resolved spontaneously within 2 days. There were no postoperative complications. Histological examination yielded stage pT1 grade I renal cell carcinoma in 3, stage pT1 grade II in 2 and multilocular cysts in 2 cases. All patients had negative surgical margins. Postoperatively, renal function as assessed by serum creatinine was unchanged. Neither local recurrences nor metastases were observed during a followup of 7 to 35 months.

Conclusions

Our results indicate that laparoscopic partial nephrectomy is feasible for small renal cell carcinoma, and is associated with low morbidity and a low complication rate.     

Microwave tissue coagulator induces renal apoptotic damage to preserved normal renal tissue following partial nephrectomy

Background  

We assessed the extent of apoptotic damage induced by the microwave tissue coagulator (MTC) in the preserved normal renal tissue following partial nephrectomy.     

Surgical management of renal tumors 4 cm. or less in a contemporary cohort

PURPOSE: We evaluated a patient cohort with renal tumors 4 cm. or less treated with partial or radical nephrectomy. We compared patient and tumor characteristics, and survival in these 2 groups. MATERIALS AND METHODS: We retrospectively analyzed the records of 670 patients with a median age of 63 years treated surgically for renal cell carcinoma between July 31, 1989 and July 31, 1997. Renal tumors 4.0 cm. or less were noted in 252 patients (38%) who underwent a total of 262 procedures, including 183 radical (70%) and 79 partial (30%) nephrectomies. Ten patients required 2 operations each because of bilateral renal cell carcinoma. Median followup was 40 months. We compared clinicopathological parameters in the partial and radical nephrectomy groups using chi-square or Wilcoxon analysis as appropriate. Survival analysis was determined by the log rank test and Cox regression model. RESULTS: The partial and radical nephrectomy groups were comparable with respect to gender ratio, tumor presentation, histological classification, pathological stage and complication rate. Median tumor size was 2.5 and 3.0 cm. in the partial and radical nephrectomy groups, respectively (p = 0.0001). Resection was incomplete in 1 patient (1.3%) in the partial and none in the radical nephrectomy group. There was no local recurrence after either procedure, and no significant difference in disease specific, disease-free and overall survival (p = 0.98, 0.23 and 0.20, respectively). CONCLUSIONS: Patients with a small renal tumor have similar perioperative morbidity, pathological stage and outcome regardless of treatment with partial or radical nephrectomy. Therefore, partial nephrectomy remains a safe alternative for tumors of this size.     

Enucleation of renal cell carcinoma in von Hippel-Lindau disease using a microwave tissue coagulator

The patient was a 37-year-old man who had undergone left nephrectomy under the diagnosis of left renal cell carcinoma associated with von Hippel-Lindau (VHL) disease 4 years ago. Computed tomography (CT) revealed 3 individual tumors 20 mm, 13 mm and 9 mm in maximum diameter in the right kidney. All three renal tumors were enucleated with a microwave tissue coagulator (MTC) without renal pedicle clamping. There were no major complications related to nephron-sparing surgery such as postoperative bleeding, persistent urine leakage and deterioration of renal function. Our findings suggest that renal tumors with VHL disease can be enucleated using a MTC safely and successfully without damaging renal function.