Videothoracoscopic excision of mediastinal masses: Indications and technique

Videothoracoscopic Excision of Mediastinal Masses: Indications and Technique Giancarlo Roviaro, MD, Carlo Rebuffat, MD, Federico Varoli, MD, Contardo Vergani, MD, Marco Maciocco, MD, and Silvio Marco Scalambra, MD Department of Surgery, S. Giuseppe Hospital, University of Milan, Milan, Italy

Mediastinal masses are generally excised through wide thoracotomies or median sternotomies. These lesions are often benign, usually asymptomatic, discovered incidentally, and relatively easy to resect. For these reasons, a minimally invasive approach is appropriate. Videothoracoscopy allows an optimal exploration of the pleural cavity and a panoramic view of the mass. Dissection is usually easy to perform, and the mass can be extracted from the thorax through a trocar incision or through a limited "utility thoracotomy." To avoid possible tumor seeding, the mass is inserted in a plastic bag before extraction. From September 1991 to January 30, 1994, 20 mediastinal masses (6 thymomas, 2 thymic cysts, 1 hyperplastic thymus, 1 fibrous tumor of the mediastinum, 2 pleuropericardial cysts, 2 thoracic teratomas, 2 large tho-

racic lipomas, 3 neurogenic tumors, and 1 bronchogenic cyst) were removed through such a minimally invasive approach. Eighteen patients had an uneventful postoperative course. Two patients hemorrhaged in the immediate postoperative period, and repeat thoracoscopy was done. In 1 patient, electrocoagulation of a bleeding intercostal artery controlled the hemorrhage. In the other, the source of bleeding could not be found, and removal of the clots and irrigation of the cavity stopped the hemorrhage. Further data and long-term follow-up are necessary, but videothoracoscopy offers a new, less invasive approach for the management of noninvasive mediastinal masses.

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mediastinal masses. Our use of videothoracoscopic surgical technique began in September 1991, and since then, all patients with an endothoracic lesion have undergone a videothoracoscopic exploration. As of January 30, 1994, we had performed 336 thoracic videoendoscopic operations. In September 1991, at the very beginning of our videothoracoscopic experience, in the course of a videoendoscopic exploration in a 24-year-old woman with an incidental finding of a mediastinal lesion, we noted a noninvasive, round, encapsulated thymoma in the anterosuperior mediastinum [5]. As it appeared to be benign and noninvasive, we proceeded videothoracoscopically with complete resection of the right lobe of the thymus. After this first patient, 28 patients with mediastinal disease underwent videothoracoscopy. Of these patients, 20 had mediastinal masses that were removed under the videothoracoscopic approach (Table 1): 6 thymomas, 2 thymic cysts, 1 hyperplastic thymus in a patient with myasthenia gravis, 1 fibrous tumor of the mediastinum, 2 pleuropericardial cysts, 2 thoracic teratomas, 2 thoracic lipomas, 3 neurogenic tumors, and 1 bronchogenic cyst. All patients were studied preoperatively as usual. All had thoracic high-resolution computed tomography. In patients with solid lesions, fine-needle aspiration biopsy of the mass was always performed. The mean age of the 20 patients having videoresection was 46 years (range, 22 to 76 years). Eight were men and 12 were women.

ecen t progress in videoendoscopic techniques has opened new options for the treatment of many thoracic diseases [1,2]. At present, thoracoscopy in many centers is considered the approach of choice for the treatment of pneumothorax, giant pulmonary bullae, and lesions that can be removed by nonanatomic pulmonary resections [3, 4]. On the other hand, videothoracoscopic excision of mediastinal masses and major pulmonary resections still are performed rarely [5-11]. Mediastinal surgery encompasses a wide spectrum of technical difficulty ranging from simple removal of pedunculate neoplasms to more complex excisions of large masses to extremely difficult resections of firmly adherent tumors invading nearby structures. In a few cases, thoracotomy and sternotomy are each too large a procedure compared with the relative simplicity of the removal. Videothoracoscopy ensures good exposure of the whole mediastinum, ensures adequate room for surgical maneuvers, and results in greatly reduced surgical trauma. This is particularly desirable for the treatment of thoracic lesions.

Material and Methods Patients Between 1967 and 1991, our experience comprised more than 2,000 pulmonary resections and 283 resections of Accepted for publication May 31, 1994. Address reprint requests to Dr Roviaro, Divisione Chirurgia, Ospedale S. Giuseppe, Cattedra di Chirurgia Generale, Universita di Milano, Via S. Vittore, 12 20123 Milano, Italy.

© 1994 by The Society of Thoracic Surgeons

(Ann Thorae Surg 1994;58:1679-84)

Indications In 15 patients, an asymptomatic mediastinal growth was found incidentally on a chest roentgenogram made for 0003-4975/94/$7.00

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Table 1. Summary of Patient Data

Patient No.

Sex

Age (y)

Utility Thoracotomy

Trocars

Postop Hospital Stay (d)

Noninvasive mixed thymoma Noninvasive epithelial thymoma Noninvasive epithelial thymoma Noninvasive epithelial thymoma Noninvasive mixed thymoma Noninvasive epithelial thymoma Thymic cyst Thymic cyst Hyperplastic thymus with myastenia Fibrous tumor of the mediastinum Pleuropericardial cyst Pleuropericardial cyst Ganglioneuroma

Yes Yes Yes Yes Yes Yes No No Yes

4 3 3 3 3 3 3 3 3

3 4 9 5 7 6 6 8 9

None None None None None None None None None

Yes

2

3

None

No No Yes

4 3 3

2 7 7

Yes Yes

3 3

4 5

None None Repeat thoracoscopy for bleeding None Intraoperative bleeding

Yes Yes Yes Yes

3 3 3 2

7 4 6 12

Yes

3

9

Pathology

1 2 3 4 5 6 7 8 9

F F F

F

26 61 58 48 58 48 60 23 35

10

F

22

11 12 13

M M

54 27 44

14 15

M M

26 24

16 17 18 19

F F F

76 63 70 56

Ganglioneuroma Preop FNA, neurofibroma; Po stop histology, malignant schwannoma Lipoma Lipoma Teratoma Dysembryoma

20

F

48

Bronchogenic cyst

M

F M

F M

F

M

Complications

None None None Repeat thoracoscopy for bleeding None

FNA = Fine needle aspiration.

other reasons. The remaining 5 patients were symptomatic or had undergone examination for follow-up of other disease. In a 26-year-old woman, a right-sided tumor of the anterosuperior mediastinum was discovered during a follow-up examination for Hodgkin's disease, which had been treated 10 years before with combined chemotherapy and radiotherapy. As fine-needle aspiration biopsy was negative and concern existed about performing mediastinoscopy in a possible postradiation fibrosis, thoracoscopy was undertaken to obtain a biopsy specimen. Exploration revealed a large (3 to 4 em), well-encapsulated tumor on the right side of the thymus gland in the anterior mediastinum, with no pleural adhesions or mediastinal postradiation fibrosis. Excision of the mass was carried out, and histology revealed a "fibrous mediastinal tumor." Two patients had symptoms caused by the mediastinal growth. Another patient, a 35-year-old woman, had been treated for myasthenia gravis for 4 years when the neurologists decided thymectomy was necessary. In a 76-year-old woman with a history of dyspnea and electrocardiographic changes, a computed tomographic scan revealed a large anterior mediastinal lipoma.

Surgical Technique Patients are intubated with a double-lumen Carlens tube, which allows selective one-lung ventilation and collapse

of the chosen lung. They are then placed in the lateral decubitus position as for a classic posterolateral thoracotomy. Two monitors are placed on either side of the patient's head to provide the best view for all members of the team. The positions of the team and scrub nurse change as required. All the surgical instruments for a thoracotomy must be ready should it be required. The first trocar, which allows the introduction of the camera, is inserted in the seventh or eighth intercostal space on the midaxillary line according to the site of the tumor. A 10-mm forward viewing endoscope is usually employed. Once the tumor has been identified, two other operating trocars are positioned in such a way as to provide the best convergence on the tumor. They are more frequently inserted in the fourth, fifth, or sixth intercostal space according to the site of the lesion, one anteriorly and one posteriorly. Normal endoscopic instrumentation is usually employed to remove mediastinal masses. An endoscopic clip-applier is also necessary for hemostasis of small vessels, but many conventional instruments can be used as needed. Removal of large specimens requires a supplementary incision. In such cases, a minimal 3 to 4-cm incision is performed anteriorly in the fourth or fifth intercostal space along the inframammary fold, as this is a wider interspace and therefore its use prevents damage to the intercostal structures and subsequent postoperative pain.

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This "utility thoracotomy" allows the extraction of the tumor at the end of the procedure; further, it can easily be extended to a classic posterolateral incision if the intervention cannot be continued thoracoscopically. Videothoracoscopic surgical intervention for mediastinal masses follows the same steps and general rules as traditional "open" mediastinal interventions. Surgical technique varies by case and depends particularly on the site of the mass, which is usually constant for each type of mediastinal tumor. At the end of the operation, if there is any concern about malignancy, the specimen must be inserted in a plastic bag to avoid tumor seeding during extraction.

Tumor Types and Myasthenia Gravis Neurinomas usually originate in the costovertebral sulcus but can develop almost anywhere there is nerve tissue [12]. The mass can usually be removed employing two operating trocars. The parietal pleura around the mass is incised with electrocoagulating scissors, and the growth is enucleated with a mounted swab. The procedure is usually dry because of the limited blood supply to the surrounding tissue. Lesser vessels are easily electrocoagulated, and the intercostal arteries can be dissected and clipped. A small thoracotomy is usually necessary to extract the specimen. In our opinion, videothoracoscopic excision is contraindicated in dumb-bell tumors, and a combined open operation in cooperation with the neurosurgeon can be planned. Mediastinal cysts constitute a heterogeneous group of tumors removable with varying degrees of difficulty [12]. Pleuropericardial cysts (the most frequent mediastinal cysts) originate at the cardiophrenic angle in close relationship with the pericardium. As a rule, a thin wall notwithstanding, they can easily be separated from the fatty areolar mediastinal tissue with a mounted swab. Deflation of the cyst after aspiration of the fluid allows a straightforward dissection and extraction through the trocars. The phrenic nerve must be accurately identified before the dissection of the mass and particularly before the use of electrocoagulation. In these cases, the utility thoracotomy is not necessary. Thymic tumors represent 45% to 50% of all mediastinal tumors. They are often well encapsulated and easily removed, but adhesion to adjacent structures can be present. Invasiveness is more important than size in determining resectability. Resection of the thymus with the thymic mass is the standard operative approach for thymomas [10, 12-14]. Videoendoscopic total thymectomy is feasible, as thoracoscopy ensures perfect exposure of all mediastinal structures. Venous drainage of the thymic gland to the innominate vein is always through a variable number of thin vessels (veins of Keynes), which drain the thymus from its posterior surface into the anterior aspect of the innominate vein. Each one of these vessels must be isolated and clipped, with care taken to avoid excessive traction to prevent accidental avulsion injury to the innominate vein. One trocar for the optics and two for the instruments are usually sufficient. During inspection of the field, the lung must be dis-

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placed posteriorly so as to expose the mammary vessels anteriorly, the phrenic nerve posteriorly, and the innominate trunk superiorly. Electrocoagulation of the mediastinal pleura usually starts on the posterior aspect of the mass, between it and the phrenic nerve, which must be recognized and preserved. The incision is then carried downward to the pericardium and upward parallel to the mammary vessels. The loose, soft anterior mediastinal tissue represents an avascular plane that is easily dissected. If the endoscopic graspers are unable to hold the mass firmly enough, the tumor can be transfixed with a suture, and gentle traction on the latter will facilitate thymic dissection from the pericardium. Adhesions are progressively divided upward toward the superior thymic poles, which are completely freed. The superior thymic veins of Keynes are separately identified and isolated with endo scissors using maximal magnification. These veins can then be sectioned after placement of two endoclips on the side of the innominate vein and a single clip on the thymic side. In the case of large tumors, dissection should start at the superior end of the pedicle, with clipping and division of the veins. In this way, torsion of the tumor around its vascular pedicle once it is isolated and consequent twisting and stripping of the delicate veins are avoided. After insertion in a plastic bag, the mass, resected along with the entire thymus, is removed through the utility thoracotomy. In myasthenia gravis, complete thymectomy is feasible through a videothoracoscopic approach. Total thymectomy, proposed as the treatment of choice, is generally performed through a transverse cervical incision with or without a sternal split or through a cervical plus full median sternal incision [15,16]. Through a left videothoracoscopic approach, which allows excellent exposure of the anterior mediastinal space and good control of the left phrenic nerve, the hyperplastic thymus can easily be identified by its pink color and its finely granular surface. Dissection of the gland is continued right up to the contralateral mediastinal pleura to free the right lobe of the thymus. Excision should be complete, including as much fatty areolar tissue as possible. The gland is then extracted through a utility thoracotomy. Results Average operating time, measured from insertion of the first trocar to skin closure, was 60 minutes (range, 25 to 180 minutes). This average was influenced by the prolonged operating time of our first few operations; as our ability has increased, the time has progressively shortened. Only 1 patient experienced complications during the operation. Patient 15 (see Table 1) underwent videoendoscopic removal on the basis of a preoperative fineneedle aspiration diagnosis of neurofibroma. Intraoperative bleeding occurred. Postoperative histology of the entire mass revealed a malignant schwannoma, and radiotherapy was initiated. Two patients who had had excision of either a neurogenic tumor or a dysembryoma hemorrhaged in the immediate postoperative period and promptly underwent a videothoracoscopic repeat inter-

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vention. In 1 patient, this revealed bleeding from the intercostal artery at the former site of insertion of a trocar. The artery was easily coagulated and clipped. In the other patient, although the source of bleeding could not be identified, removal of the clots and irrigation with saline solution stopped the hemorrhage. Two units of blood were transfused. These 2 patients were discharged on the seventh and 12th postoperative days, respectively. The average postoperative hospital stay was 6 days (range, 2 to 12 days). All patients experienced a little postoperative pain, relieved with common minor analgesics (nonsteroid, antiinflammatory drugs), which were administered for no more than 2 days. Cosmetic results were very good. The follow-up ranges between 4 and 28 months. No patient has persisting pain in the sites of the trocars or the minimal utility thoracotomy. To date, no patient has recurrence of the disease. Patients operated on for thymoma have been followed up with computed tomography of the chest, and no sign of recurrence has been found. The patient with myasthenia gravis is well and free from symptoms. The patient with a malignant schwannoma is receiving radiotherapy.

Comment At present, the diagnosis of mediastinal lesions can be performed through a wide variety of techniques. Computed tomography is essential, as it provides the most useful information for diagnosis and treatment, shows the morphology of the mass, precisely defines its relationship with adjacent structures, and provides data on its density and vascularization. Moreover, it gives the opportunity to determine the presence of a capsule or a cleavage plane and to rule out invasion of surrounding structures, which is of great importance for surgical treatment. However, computed tomography does not have complete specificity and sensitivity, and definite information can be obtained only intraoperatively [17]. In our department, every solid mediastinal lesion is also studied by fine-needle aspiration biopsy or mediastinoscopy depending on its site. In mediastinal lesions of surgical interest, we always use videothoracoscopy as the first step of the operation, as it reveals invasiveness that may not have been demonstrated by previous staging or computed tomographic scanning and allows us to determine the feasibility of direct thoracoscopic removal of well-encapsulated tumors. In the case of nonencapsulated masses invading mediastinal fatty areolar tissue or adjacent organs, videothoracoscopy is useful to obtain selective biopsy specimens, to evaluate the resectability of the lesion, and consequently to decide whether to proceed with excision by a thoracotomy or whether to postpone surgical treatment until after preoperative chemotherapy [9-11,14]. We believe that, at present, videothoracoscopic surgery is indicated for mediastinal lesions where a thoracotomy incision seems too large for the relative ease of resectability of the mass (eg, thymic cysts). It is also feasible for larger, noninfiltrating tumors, even though

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great care must be taken to avoid vascular or nerve injuries. Well-encapsulated thymic neoplasms, dysontogenetic tumors, and nervous tumors of the costovertebral sulcus can all be removed thoracoscopically [9, 10, 14, 18]. In strictly selected cases, minimal invasiveness can justify videothoracoscopic removal of pleuropericardial cysts. These lesions were formerly excluded from operation, as a thoracotomy seemed too extensive for the removal of a benign and often asymptomatic condition. In the case of very large or symptomatic cysts or those that cause great psychological distress, the surgeon can remove the cyst with the videothoracoscopic approach. Videothoracoscopic removal is contraindicated in the case of invasive malignant tumors. If excision is technically feasible and oncologically justified, it must be performed through a thoracotomy or sternotomy. Videothoracoscopy provides an excellent transpleural approach to the mediastinum, thus allowing careful removal of the mass by combined blunt and sharp dissection; however, training in open chest operations is mandatory because of the paramount importance of mediastinal organs. A perfect command of anatomy and a wide experience in mediastinal pathology are required. In our experience, the excision has not presented a great difficulty, and complete removal of the lesion is always accomplished without major difficulty. The videothoracoscopic approach undoubtedly offers functional and cosmetic advantages and avoids the sequelae of thoracotomies: pain is much reduced, and respiratory function is better. Further, the utility thoracotomy, if performed along the inframammary fold, gives very satisfactory cosmetic results. Postoperative care does not differ from that after an open chest operation. However, there is minimal trauma, greatly reduced postoperative pain, and more rapid recovery of normal function and activity. Pain, if present, is minimal and usually well controlled by minor analgesics. Complications from videothoracoscopic removal of mediastinal masses do not differ greatly from those with traditional surgical procedures. Even though the risk is relatively small in the case of well-encapsulated and benign masses, great caution is necessary to avoid causing injury to any of the major mediastinal vessels or the phrenic nerve. The most frequent complication after a thoracic operation is bleeding, and it can require repeat thoracotomy, which often does not locate the bleeding source. In our videothoracoscopic experience, the 10% rate (2/20) of postoperative hemorrhage is high, but our series is still quite small, and the occurrence of even a single case greatly affects the overall rate. For this reason, the rate is not significant and is comparable to that in conventional series. The 2 patients in whom bleeding developed were seen early in our videothoracoscopic series. In 1, the bleeding was due to an intercostal artery lacerated by a trocar of old design that we no longer use. Further, in these 2 patients, repeat thoracoscopy allowed us to resolve the complication. Rapid recovery allows early discharge of patients, even though in our country, many patients prefer to stay in the

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hospital longer. This is the result of social needs more than clinical reasons, as our health system guarantees free hospitalization but does not provide satisfactory home care. These considerations alone account for the relatively prolonged hospital stay of our patients. In conclusion, the excision of benign mediastinal masses particularly lends itself to a minimally invasive approach, as the operative technique does not present any great difficulty and the exposure of the field through wide-screen monitors is superb. Videothoracoscopic surgery is indicated for well-encapsulated benign mediastinal lesions, and it is feasible for larger noninfiltrating tumors, with great care taken to avoid vascular and nerve injuries. It is contraindicated in the case of invasive malignant tumors. The functional and cosmetic advantages for the patient are unquestionable. This new surgical approach requires further data, larger series, and longer follow-up to be fully evaluated and standardized. References

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Maciocco M. Videoendoscopic pulmonary lobectomy for cancer. Surg Laparosc Endosc 1992;2:244-7. Roviaro G, Varoli F, Rebuffat C, et al. Major pulmonary resections: pneumonectomies and lobectomies. Ann Thorac Surg 1993;56:779-83. Roviaro GC, Rebuffat C, Varoli F, et al. Videothoracoscopic pulmonary lobectomies for cancer. In: Steichen FM, Welter R, eds, Minimally invasive surgery and new technology. St. Louis: Quality Medical Publishing, 1994:700-3. Roviaro GC, Rebuffat C, Varoli F, et al. Videothoracoscopic excision of mediastinal masses. In: Steichen FM, Welter R, eds. Minimally invasive surgery and new technology. St. Louis: Quality Medical Publishing, 1994:711-3. Landreneau RJ, Dowling RD, Castillo WM, Ferson PF. Thoracoscopic resection of an anterior mediastinal tumor. Ann Thorac Surg 1992;54:142-4. Kern JA, Daniel TM, Tribble CG, Silen ML, Rodgers BM. Thoracoscopic diagnosis and treatment of mediastinal masses. Ann Thorac Surg 1993;56:92-6. Shields TW. Primary tumors and cysts of the mediastinum. In: Shields TW, ed. General thoracic surgery. Philadelphia: Lea & Febiger, 1989:1096-1123. Trastek VF, Payne WS. Surgery of the thymus gland. In: Shields TW, ed. General thoracic surgery. Philadelphia: Lea & Febiger, 1989:1124-36. Acuff TE, Mack MJ, Ryan WH, Bowman RT, Douthit MB. Thoracoscopic thymoma resection [Letter]. Ann Thorac Surg

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thymectomy for myasthenia gravis. Results. J Thorac Cardiovasc Surg 1988;95:747-57. 16. Cooper JD, Al-jilaihawa AN, Pearson FG, Humphrey JG, Humphrey HE. An improved technique to facilitate transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 1988;45:242-7. 17. Kohman LJ. Approach to the diagnosis and staging of mediastinal masses. Chest 1993;103:3285-305. 18. Landreneau RJ, Dowling RD, Ferson PF. Thoracoscopic resections of a posterior mediastinal neurogenic tumor. Chest 1992;102:1288-90.

INVITED COMMENTARY Because of the endorsement potentially implied by publication, the indications and techniques for excising mediastinal masses reported by Dr Roviaro and colleagues deserve a cautionary comment. When the target is a bronchogenic or thymic cyst, the ratio of the chest wall injury by a "wide thoracotomy" to the intrathoracic surgical mission appears disproportionate, and videothoracoscopic excision seems intuitively preferable. The question of whether the benefits claimed ("pain is much reduced, and respiratory function is better" and "functional and cosmetic advantages...are unquestionable") are real or imaginary is not answered and awaits objective measurements. It is remarkable how little such evidence has been sought and reported in the surgical literature. Roviaro and associates have an important opportunity to compare the impact of their "utility thoracotomy" with the standard thoracotomies they continue to employ in appropriate cases. It may be provable that the very brief

use of the rib spreader they advocate during removal of the specimen causes less residual pain and disability than conventional thoracotomy. Strong words like "unquestionable" do not dismiss the question or the need for an answer based on evidence. In the interim, the "wide" posterolateral thoracotomy is becoming a "straw man." This incision once included a complete or partial costectomy as a routine component that was believed by many to reduce pain. In the hands of many traditional surgeons who have not yet accepted video-assisted thoracic surgery, (VATS), open thoracotomy gradually is approaching the length and width of the "utility thoracotomy." Readers should not accept the incomplete thymectomy performed in Roviaro and associates' first patient as an appropriate videothoracoscopic technique because the residual thymic lobe may generate another thymoma at a later date. The possibility of pleural or chest-wall seeding during the removal of a thymoma by their technique deserves emphasis. Although the problem of trocar site