International Journal of Urology (2015) 22, 844--849

doi: 10.1111/iju.12834

Original Article: Clinical Investigation

Transumbilical laparoendoscopic single-site surgery versus conventional laparoscopy for the resection of retroperitoneal paragangliomas Weifeng Xu,1 Hanzhong Li,1 Zhigang Ji,1 Weigang Yan,1 Yushi Zhang,1 Xuebin Zhang1 and Qian Li2 1

Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China, and Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA

2

Abbreviations & Acronyms ASA = American Society of Anesthesiologists BMI = body mass index CL = conventional laparoscopy LESS = laparoendoscopic single-site surgery SIRS = systematic inflammation reaction syndrome VAS = visual analog scale Correspondence: Hanzhong Li M.D., Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China. Email: [email protected] Received 21 November 2014; accepted 10 May 2015. Online publication 26 June 2015

Objectives: To compare transumbilical laparoendoscopic single-site surgery with conventional laparoscopy for the resection of retroperitoneal paragangliomas. Methods: In the present case–control study, we compared 11 transumbilical laparoendoscopic single-site surgery procedures with 22 conventional laparoscopy procedures carried out to treat retroperitoneal paragangliomas between June 2004 and October 2013 at Peking Union Medical Hospital, Beijing, China. Operative time, estimated intraoperative blood loss, blood transfusions, intraoperative hypertension, intraoperative hypotension, highest intraoperative systolic blood pressure, lowest intraoperative systolic blood pressure, postoperative fatigue time, postoperative systematic inflammation reaction syndrome, 24-h postoperative visual analog scale scores, postoperative hospital stay duration, and postoperative complications were recorded and analyzed. Results: There were no significant differences in patient characteristics. All surgical procedures were successfully completed in both groups. Minor complications occurred in one case in the laparoendoscopic single-site surgery group and in two cases in the conventional laparoscopy group. In the laparoendoscopic single-site surgery group, the operative time was longer than that in the conventional laparoscopy group (P = 0.001). There were no significant differences in terms of intraoperative hypertension, intraoperative hypotension, highest intraoperative systolic blood pressure, lowest intraoperative systolic blood pressure, estimated blood loss, postoperative fatigue time, postoperative hospital stay or systematic inflammation reaction syndrome between the two groups. The 24-h postoperative visual analog scale score was lower in the laparoendoscopic single-site surgery group (P = 0.002). No recurrence or metastases were observed over the duration of the postoperative follow up. Conclusions: In properly selected patients, transumbilical laparoendoscopic single-site surgery is a feasible, safe and effective procedure for the surgical treatment of retroperitoneal paragangliomas.

Key words: laparoscopy, paraganglioma, pheochromocytoma, transumbilical laparoendoscopic single-site surgery.

Introduction Paraganglioma, also called extra-adrenal pheochromocytoma, is a chromaffin cell tumor located at various sites along the sympathetic chain.1,2 More than 85% of paragangliomas occur below the diaphragm, with the para-aortic region being the most common site.3–5 A definitive treatment for paragangliomas is surgical resection, and the conventional surgical treatment consists of open exploration and resection. CL with minimal invasion has been widely used on retroperitoneal tumors, but it is still challenging for paraganglioma resection because of the excessive catecholamine release caused by the operative stimulation. LESS surgery, which aims to carry out laparoscopic surgery by consolidating all ports within a single skin incision, is a promising technique developed from CL surgery, with major improvements in the cosmetic results, moderate postoperative pain and reduced postoperative complications.6,7 After first being carried out for kidney resection in 2007,8 transumbilical LESS has been successfully introduced for various operations on the urinary system, including adrenal pheochromocytoma,9 and its feasibility and safety have been shown.10–16 844

© 2015 The Japanese Urological Association

LESS vs CL resection of paragangliomas

However, compared with pheochromocytoma, paraganglioma is a more complicated condition for surgical treatment because of the variations in tumor anatomy, the possibility of dense adhesions and/or high vascularity around the tumor, as well as the proximity to major blood vessels. To date, no case series report focused on transumbilical LESS resection of retroperitoneal paragangliomas has been published. In the present case–control study, our aim was to assess the feasibility of transumbilical LESS for paraganglioma in a relatively populous study population, by comparing it with the CL method.

Methods Patients The present case–control study was approved by the institutional review board of Peking Union Medical College Hospital, Beijing, China, and was Health Insurance Portability and Accountability Act compliant. We retrospectively searched our database from June 2004 to October 2013 and collected the cases with primary single retroperitoneal paragangliomas that were postoperative-pathology proven, and all of these patients underwent transumbilical LESS or CL surgery at Peking Union Medical College Hospital. Patients with the following were excluded: (i) multiple tumors; (ii) recurrent tumors; (iii) tumors larger than 5 cm in maximal diameter on computed tomography;17,18 and (iv) a BMI more than 31.19 In the study period, a total of 45 qualified patients were found. Considering the improvements with LESS compared with CL, such as cosmetic results, moderate postoperative pain and reduced incision related complications,6,7 from April 2010 to June 2013, a total of 11 patients with single retroperitoneal paragangliomas underwent the LESS surgery (LESS group). Preoperatively, all 11 patients gave consent to undergo transumbilical LESS surgery as the preferred operative approach, with CL or open surgery as an alternative when necessary. From June 2004 to October 2013, a total of 34 cases with paragangliomas underwent CL surgery, from which control cases (n = 22) were matched two-to-one with LESS patients for age, sex, BMI, tumor size and tumor location (left or right).

Preoperative preparation Preoperatively, all of the enrolled patients received a-adrenergic blockade (phenoxybenzamine) starting at a dose of 15 mg per day and gradually increasing to 30–90 mg per day over 2–4 weeks. Occasionally, b-adrenergic blockade was instituted after a-adrenergic blockade was established if tachycardia developed. The final dose of phenoxybenzamine was given on the morning before surgery.

Operative methods All of the surgeries were carried out by the same surgical team with 10 years of experience in the laparoscopic management of pheochromocytoma and paraganglioma. All surgeries were carried out under general anesthesia administered through an endotracheal tube. Before the surger© 2015 The Japanese Urological Association

ies, catheters were inserted into the radial artery and the jugular vein to monitor the arterial blood pressure and the central venous pressure, respectively.

LESS procedure An X-Cone (Storz, Tuttlingen, Germany) or TriPort (Olympus, Tokyo, Japan) was applied in the multichannel trocar. The operating instruments included lengthened pre-bending of instruments and conventional laparoscopes (Storz). The endoscope was a 5-mm laparoscope with a 30° flexible front end (EndoEYE; Olympus). The patients were placed lying on the unaffected side in a 70° recumbent position. After a small paraumbilical incision (2.5–3.0 cm), the skin was then opened layer by layer, and a monoporate multichannel trocar was placed into the abdominal cavity (Fig. 1a). Using a CO2 pneumoperitoneum machine, pneumoperitoneal pressure was maintained at 12– 15 mmHg, and subsequently, the operating instruments were placed. For left-sided tumors, the side peritoneum was incised along the paracolic sulci of the descending colon, and the splenocolic ligament was dissected to fully isolate the descending colon and the splenic flexure of the colon. Then, the descending colon was turned inward to fully expose the tumor. To fully expose the tumor above the renal pedicle level, the cauda pancreatis was isolated along Gerota’s fascia, and was then pushed inward. For tumors below the renal pedicle level, these procedures were not necessary. Gentle traction was required during dissection of the splenocolic ligament to prevent splenic injury. For right-sided tumors, the side peritoneum was incised along the paracolic sulci of the ascending colon. Then, the ascending colon and the duodenum were turned inward to expose the edge of the postcava. For tumors above the level of the renal pedicle, the deltoid ligament and the hepatocolic ligament on the right side of the liver were dissected. However, for right-sided paragangliomas in a high location, an additional pore was usually required for liver retraction, and needle-type auxiliary equipment could be used. The liver was pushed upward to expose the tumor, and an ultrasound scalpel was used to isolate the tumor along the tumor capsule. The vessels feeding the tumor were incised directly or with a Hem-o-lok clip (Fig. 1b,c). The specimens were collected with a self-made bag, and were removed through the umbilical incision. Then, an abdominal drainage tube was applied (Fig. 1d). In two of 11 LESS cases, the tumors were obviously protruding into the abdominal cavity. Therefore, a transmesenteric approach was preferred. From medial to the colon, the mesentery was dissected to expose the tumor, followed by tumor resection. The dissection followed the same path, but avoided the mesentery vessels.

CL procedure CL surgery was carried out using the method described in the literature.2 Under general anesthesia, the patient was placed in a 70° recumbent position. Four ports were placed 845

W XU ET AL.

(a)

(b)

(c)

(d)

Fig. 1 Image of transumbilical LESS surgery. (a) Transumbilical multichannel trocar (X-cone) placement. (b,c) Resection of the tumor. (d) Drainage tube placement post-surgery.

transperitoneally. The processes of tumor exposure, isolation and resection were similar to those used for LESS surgery.

hilum, superior right renal hilum and inferior right renal hilum.

Perioperative data collection

Statistical analysis

The following perioperative data were collected, including the operative time (min), estimated blood loss (mL), the incidence of intraoperative hypertension (defined as systolic blood pressure >180 mmHg or intraoperative systolic pressure increase of >30% compared with that before anesthesia), the incidence of intraoperative hypotension (defined as systolic blood pressure 38 or 90 b.p.m.; (iii) a respiratory rate >20 breaths/min or carbon dioxide partial pressure in arterial gas 12 000 cells per mm3 or 10%. The duration of SIRS was calculated in days.14,20 Common symptoms of paraganglioma, including hypertension, headache, palpitation and sweating, were also collected.5 Based on the laterality and considering the relationship between the tumor and the renal pedicle,2 the anatomical locations of the paragangliomas were classified into four groups, superior left renal hilum, inferior left renal

All statistical analyses were carried out with SPSS Software, version 17.0 (SPSS, Chicago, IL, USA). Continuous variables, such as age, BMI, tumor size, operative time, estimated blood loss, postoperative hospital stay and postoperative exhaust time, were expressed as the mean  SD and compared using Student’s t-test. Categorical data were compared with Pearson’s v2-test or Fisher’s exact probability test. P < 0.05 was considered statistically significant.

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Results The participants’ baseline data and tumor associated data are summarized in Table 1. No significant differences in sex, age, BMI, tumor size or operative side were observed between the two groups (P > 0.05). All of the LESS and CL procedures were successfully completed without conversion to open operations, and none of the surgeries using additional ports were enrolled in the LESS group. Postoperative histopathology showed that all of the tumors in the two groups were resected successfully with tumor-free margins. The operational data are presented in Table 2. The operative time for the LESS group was significantly longer than that of CL group (114.5  33.8 min vs 80.2  21.5 min, P = 0.001). Further analysis found that in the LESS group, approximately 32.5 min more time was spent on the first five patients than on the subsequent six cases (132.5  43.8 min vs 100  14.1 min, P = 0.123), although it was not statistically significant. © 2015 The Japanese Urological Association

LESS vs CL resection of paragangliomas

Table 1 Demographic data and tumor characteristics from the two groups

Age Male/female BMI (kg/m2) Tumor diameter (cm)† Location (left/right) Left superior renal hilum Left inferior renal hilum Right superior renal hilum Right inferior renal hilum ASA grade Grades I–II Grade III Hypertension Persistent hypertension Paroxysmal hypertension Headache Palpitation Sweating

LESS group (n = 11)

CL group (n = 22)

36.2  9.2 5/6 22.9  1.4 3.77  0.64 7/4 3 4 2 2

34.8  10.1 8/14 22.8  1.6 4.25  0.67 14/8 7 7 3 5

10 1 10/11 3 7 6/11 4/11 5/11

19 3 18/22 8 10 11/22 5/22 8/22

P-value 0.691 0.714 0.975 0.055 1.0

1.0

Data presented as mean  SD. †Measured by preoperative computed tomography.

The average blood loss in the LESS group was less than that in the CL group, but no statistical significance was shown (84.5  36.1 mL vs 114.5  69.6 mL, P = 0.192). The VAS scores of the LESS group were significantly lower than those of the CL group (4.4  0.5 vs 5.5  0.9, P = 0.002). Between the two groups, no significant differences were shown for the following variables: the frequency of SIRS (5/11 vs 12/22, P = 0.721), the postoperative exhaust time (1.7  0.4 days vs 1.7  0.7 days, P = 0.845) and the length of postoperative hospital stay (5.2  1.2 days vs 5.3  1.5 days, P = 0.929). For intraoperative hemodynamics, the two groups did not show significant differences in the incidence of hypertension (6/11 vs 10/22, P = 0.721), the incidence of hypotension (2/11 vs 5/22, P = 1.0), the mean highest intraoperative systolic blood pressure (171.4  27.1 mmHg vs 162.7  22.1 mmHg, P = 0.335) and the mean lowest intraoperative systolic blood pressure (97.7  17.1 mmHg vs 95  15.9 mmHg, P = 0.654). In total, three complications were observed in the present study, one lymphorrhagia and one infection of the incisional wound in the CL group, and one lymphorrhagia in the LESS group. The two patients with lymphorrhagia were treated by prolonging the indwelling time of the drainage tube to 10 days and 2 weeks after the operation. In the one patient with infection of the incisional wound, the wound was healed 12 days after the operation by changing dressings. None of the patients underwent reoperation. Postoperatively, the LESS and CL groups were followed up for 3–38 and 5–87 months, respectively. During the follow-up period, no tumor recurrence or metastasis occurred. © 2015 The Japanese Urological Association

Table 2 Perioperative data for the LESS and CL groups

Operative time (min) Estimated blood loss (mL) Blood transfusion (cases) Intraoperative hypertension (cases) Mean highest intraoperative systolic BP (mmHg) Intraoperative hypotension (cases) Mean lowest intraoperative systolic BP (mmHg) Postoperative exhaust time (days) Postoperative hospital stay (days) Complications (cases) Clavien–Dindo classification Grade I Grade II SIRS No. patients Range (days) VAS

LESS

CL

P-value

114.5  33.8 84.5  36.1

80.2  21.5 114.5  69.6

0.001 0.192

0 6/11 171.4  27.1

2/11 97.7  17.1

0 10/22 162.7  22.1

5/22 95  15.9

1.0 0.721 0.335

1.0 0.654

1.7  0.4

1.7  0.7

0.845

5.2  1.2

5.3  1.5

0.929

1/11

2/22

1.0

1

1 1

5/11 1.2  0.4 (1-2) 4.4  0.5

12/22 1.5  0.8 (1-3) 5.5  0.9

0.721 0.447 0.002

Data presented as mean  SD.

Discussion In the present study, we retrospectively evaluated the feasibility and safety of LESS for paraganglioma compared with CL surgery. All of the LESS operations were carried out smoothly without conversion to CL or open surgery. Compared with the CL, the LESS procedures did not show significant differences in intraoperative hemorrhage amounts, the frequency of transfusion, intraoperative hemodynamic fluctuation, postoperative fatigue time or postoperative SIRS incidence and duration. Although the operative time for LESS was longer than that of CL surgery, the LESS group showed less postoperative pain. The present study could be a valuable source for the future deployment of the LESS method for paraganglioma. Transumbilical LESS surgery has been shown to be safe and feasible for the treatment of pheochromocytomas, but not for paragangliomas.10–16 In the present study, all of the 11 cases of transumbilical LESS resection for paragangliomas were carried out successfully without conversion to CL operations or open surgery, and the specimen’s histological margin positivity also showed the significant success of this technique. Additionally, no severe postoperative complications and no follow-up recurrence or metastasis were found in this series. Thus, all of these outcomes implied the reliability and safety of transumbilical LESS surgery for retroperitoneal paraganglioma. 847

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When we analyzed the successful experience of our LESS cases, the surgical team was primarily considered. Because of the various tumor sites and the complex adjacent great vessels, laparoscopic resection of paragangliomas was regarded as having a higher risk than the conventional open approach, which strongly indicates performance by senior surgeons with sufficient laparoscopic experience. In the present study, the surgical team had experience of hundreds of laparoscopic resections of pheochromocytomas and paragangliomas, and were well trained in the anatomy and laparoscopic vascular sutures surrounding the tumor, which were all critical for the successful completion of LESS. The manipulation of pheochromocytomas and paragangliomas during surgery causes the excessive release of catecholamines, which possibly results in severe and deadly complications, such as hypertensive crisis and arrhythmia. Laparoscopic resection has been reported to reduce the release of catecholamines compared with conventional open approaches.21–25 Yuan et al. reported the effect of LESS for pheochromocytoma, and they found no significant difference in hemodynamics between the LESS and CL groups.15 Our results were consistent with those reported by Yuan et al. The two groups did not show significant differences in the incidence of hypertension and hypotension, and the mean maximum and minimum systolic blood pressure. Regarding the intraoperative data, the present study showed longer operative times in the LESS group compared with that in the CL group (114.5  33.8 min vs 80.2  21.5 min, P < 0.05). However, a previous report that compared LESS and CL adrenalectomies showed no significant differences between the two methods for operative time.26 In their study, more pheochromocytomas and larger tumors were placed in the CL group, increasing the complexity of the operation and, accordingly, the operative time. For our series, the longer operative time in the LESS group possibly arose from learning LESS as a new method for the surgical team, because we found longer operative times in the first five patients than those in the subsequent six patients (132.5  43.8 min vs 100  14.1 min, P = 0.123), although there was no statistical significance, which might be attributed to the small sample size. Furthermore, the mean difference (34.3 min) in the operative time between the case and control groups in the present study was clinically tolerated. Compared with pheochromocytoma, paraganglioma is more complicated because of its anatomical variations. Based on our experience with LESS surgery for retroperitoneal paragangliomas, different strategies were deployed according to the tumor locations.

1 Short operating distance reduced the number of instrument collisions when the tumor was located at lower levels and near the umbilicus. 2 Tumors that were located more superiorly were often shielded by the spleen and the cauda pancreatis on the left side, and were hidden behind the liver on the right side, making tumor exposure difficult. In these cases, the splenic and hepatic flexure of the colon should be fully isolated. In the two patients with a right-sided tumor in this study, the tumors were located at a low

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location with a small diameter (3.5 and 3 cm). Therefore, the tumors were not hidden by the livers, and the operation could be carried out through a single pore. Careful technique is necessary because of the abundant blood supply of paragangliomas, the irregular sources of arterial blood and the complex distribution of the venous return. The confirmed vessels could be sealed with an ultrasound knife or severed post-occlusion with hemostatic clips to avoid rupturing the vessels and subsequent hemorrhage. For LESS surgery, a clearer surgical field is necessary. Obvious hemorrhage could severely influence the operative process and could even lead to conversion to CL surgery. 3 In the two cases with paragangliomas protruding into the abdominal cavity, no isolation of the colon was carried out. Instead, the mesentery was dissected for direct exposure and resection of the tumors. This approach was simple and efficient, but mesentery dissection should be carried out carefully along the mesenteric vessels to avoid mesentery injuries and subsequent intestinal ischemia. Although increasingly carried out, the LESS technique remains challenging. During the operation, the surgical instruments are placed parallel to each other, and frequent collisions are inevitable, which increases the surgical complexity. In addition, the endoscope and the operating instruments are oriented in the same direction, which might cause sight interference. Although the introduction of curved instruments reduced the frequency of collisions, it required more time to learn and master. Therefore, the combined use of conventional and curved instruments was preferred according to our experience, which not only helped to reduce the collision and interference, but also shortened the learning process and improved the surgical reliability. In our center, the patients undergoing LESS were selected by the surgical team in addition to providing consent. In the early phases of carrying out the new LESS approach, tumor size and patient shape were controlled to improve the possibility of a successful procedure following the principle of pursuing ease before difficulty. Smaller tumors were selected, because increasing tumor size usually corresponds to a higher possibility of malignancy, more internal vascularity of the tumor and a higher risk of the procedure.17,18 Obese patients were excluded because the increasing thickness of adipose could increase the difficulty of tumor exposure as well as the complexity of the operation.19 The present study had some limitations. First, it was a retrospective study, and could have suffered from selection and recall biases. To overcome these shortcomings, prospective matched-pair studies are required. Second, even though this study was a research study on transumbilical laparoendoscopic single-site resection of paragangliomas with the largest sample size, to the best of our knowledge, it still suffered from the limitation of a small sample size. Therefore, the present study is preliminary research on LESS for the treatment of paraganglioma. To overcome this shortcoming, a larger number of samples with tumors in different locations is still required for a comparison between the outcomes of the

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LESS vs CL resection of paragangliomas

two surgical approaches. Third, although the surgeons in this study were experienced in laparoscopic surgery, they were not as experienced in single-site laparoscopic surgery. The differences between these two surgical approaches might have influenced the results of the present study. Fourth, the distribution of tumors in different areas varied. Finally, there was no recurrence among our patients, but the follow-up duration was relatively short (range 3–38 months). It is necessary to observe patients over a longer follow-up period.27,28 In conclusion, in properly selected patients, transumbilical LESS surgery was a feasible and safe procedure for the resection of retroperitoneal paragangliomas. Compared with CL surgery, LESS was more comfortable postoperatively for the patients because of less pain, although it required more operative time. Further research on LESS with expanded inclusion criteria to include larger paragangliomas or higher BMI is warranted.

Acknowledgment The authors thank the staff of the Department of Urology for their assistance during the study.

Conflict of interest None declared.

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10 He Y, Chen Z, Luo YC, Fang XL, Chen X. Laparoendoscopic single-site retroperitoneoscopic adrenalectomy for pheochromocytoma: case selection, surgical technique, and short-term outcome. J. Endourol. 2014; 28: 56–60. 11 Zhang X, Shi TP, Li HZ, Ma X, Wang BJ. Laparo-endoscopic single site anatomical retroperitoneoscopic adrenalectomy using conventional instruments: initial experience and short-term outcome. J. Urol. 2011; 185: 401–6. 12 Walz MK, Groeben H, Alesina PF. Single-access retroperitoneoscopic adrenalectomy (SARA) versus conventional retroperitoneoscopic adrenalectomy (CORA): a case-control study. World J. Surg. 2010; 34: 1386–90. 13 Jeong BC, Park YH, Han DH, Kim HH. Laparoendoscopic single-site and conventional laparoscopic adrenalectomy: a matched case-control study. J. Endourol. 2009; 23: 1957–60. 14 Agha A, Hornung M, Iesalnieks I, Glockzin G, Schlitt HJ. Single-incision retroperitoneoscopic adrenalectomy and single-incision laparoscopic adrenalectomy. J. Endourol. 2010; 24: 1765–70. 15 Yuan X, Wang D, Zhang X, Cao X, Bai T. Retroperitoneal laparoendoscopic single-site adrenalectomy for pheochromocytoma: our single center experiences. J. Endourol. 2014; 28: 178–83. 16 Hattori S, Miyajima A, Maeda T et al. Does laparoendoscopic single-site adrenalectomy increase surgical risk in patients with pheochromocytoma. Surg. Endosc. 2013; 27: 593–8. 17 Toniato A, Boschin IM, Opocher G, Guolo A, Pelizzo M, Mantero F. Is the laparoscopic adrenalectomy for pheochromocytoma the best treatment. Surgery 2007; 141: 723–7. 18 Castillo OA, Vitagliano G, Secin FP, Kerkebe M, Arellano L. Laparoscopic adrenalectomy for adrenal masses: does size matter. Urology 2008; 71: 1138– 41. 19 Hasegawa M, Miyajima A, Jinzaki M et al. Visceral fat is correlated with prolonged operative time in laparoendoscopic single-site adrenalectomy and laparoscopic adrenalectomy. Urology 2013; 82: 1312–8. 20 Bone RC, Balk RA, Cerra FB et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. CHEST J. 1992; 101:1644–55. 21 Flavio RM, Faramarzi-Roques R, Tauzin-Fin P, Vallee V, de Vasconcelos PRL, Ballanger P. Laparoscopic surgery for pheochromocytoma. Eur. Urol. 2004; 45: 226–32. 22 Kercher KW, Park A, Matthews BD, Rolband G, Sing RF, Heniford BT. Laparoscopic adrenalectomy for pheochromocytoma. Surg. Endosc. 2002; 16: 100–2. 23 Li H, Yan W, Ji Z et al. Experience of retroperitoneal laparoscopic treatment on pheochromocytoma. Urology 2011; 77: 131–5. 24 Kercher KW, Novitsky YW, Park A, Matthews BD, Litwin DE, Heniford BT. Laparoscopic curative resection of pheochromocytomas. Ann. Surg. 2005;241:919–26; discussion 926–8. 25 Miccoli P, Bendinelli C, Materazzi G, Iacconi P, Buccianti P. Traditional versus laparoscopic surgery in the treatment of pheochromocytoma: a preliminary study. J. Laparoendosc. Adv. Surg. Tech. 1997; 7: 167–71. 26 Ishida M, Miyajima A, Takeda T, Hasegawa M, Kikuchi E, Oya M. Technical difficulties of transumbilical laparoendoscopic single-site adrenalectomy: comparison with conventional laparoscopic adrenalectomy. World J. Urol. 2013; 31: 199–203. 27 Goldstein RE, O’Neill JA Jr, Holcomb G3 et al. Clinical experience over 48 years with pheochromocytoma. Ann. Surg. 1999;229:755–64; discussion 764–6. 28 Scott HW Jr, Halter SA. Oncologic aspects of pheochromocytoma: the importance of follow-up. Surgery 1984; 96: 1061–6.

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Transumbilical laparoendoscopic single-site surgery versus conventional laparoscopy for the resection of retroperitoneal paragangliomas.

To compare transumbilical laparoendoscopic single-site surgery with conventional laparoscopy for the resection of retroperitoneal paragangliomas...
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