Victor A.Tarasov, Yuriy K.Sharov, Pyotr I.Azarov, Evgeny S.Pobegalov, Vladimir V.Stavrovietskiy, Igor V.L'vov, Igor A.Kondrashov, Konstantin P.Zhidkov, Mikhail B.Blium, Armen G.Andreassian


DIAGNOSIS AND SURGERY OF MEDIASTINAL MASSES



SUMMARY

MATERIAL AND METHODS. 603 patients aged 6 - 82 with mediastinal masses underwent major surgery. 408 masses were benign or noninvasive, 195 - malignant or invasive; 134 of the latter invaded 1 - 9 adjacent organs and structures. 49 patients had 82 great vessels invaded. 40 patients demonstrated signs of mediastinal compression. 550 radical, extended or combined operations, 36 decompressive ones, and 17 explorative ones were performed. RESULTS. Postoperative morbidity made up 7.0%, mortality - 3.0%, both being the lowest after simple and extended radical or decompressive surgery, and the highest - after explorations. CONCLUSIONS. Surgery is indicated in all mediastinal masses due to potential risk of mediastinal compression. In cases of advanced complicated tumours, decompressive surgery is the most safe option, exploration being the most dangerous. Replacement of invaded great veins with polytetrafluorethylene grafts should become a routine stage of radical and decompressive surgery of advanced invasive mediastinal neoplasms. Major surgery of mediastinal lymphomas has a number of benefits and may be performed without mortality and with minimal morbidity when detecting surgical extent accurately and carefully. Bilateral resection of invaded phrenic nerves does not lead to fatal respiratory failure and may be performed if needed.
 

TEXT

BACKGROUND. Surgical tactics in mediastinal neoplasms is defined by risks of their malignization, invasion and compression of vitally important organs. Removal of mediastinal cysts and non-invasive tumours usually doesn't present serious problems, provided that choice of surgical approach is adequate. Yet, invasion of vitally important organs significantly limits the possibility of radical surgery. Another problem is mediastinal compression which might be caused by both malignant and benign masses. Superior vena cava and/or brachiocephalic veins are frequently affected: mediastinal masses are now considered to be the most common reason of superior vena cava syndrome (1). Major airway compression by mediastinal neoplasms produces severe respiratory insufficiency which, in a number of cases, can't be successfully managed by artificial ventilation. As for mediastinal lymphomas, therapeutic approach seems to be rather contradictory: on one hand, lymphomas are system diseases, and major surgery is generally considered not to be appropriate for their treatment; on another hand, extent of some mediastinal lymphomas and severity of produced symptoms lead a number of authors to major surgical excisions, which, in their opinion, not only provide rapid improvement of patients' condition, but also facilitate consecutive specific therapy. With all disputability of this problem, the surgeon's part in treatment of these patients seems to lack accurate estimation.

MATERIAL AND METHODS. 603 patients with mediastinal tumours and cysts underwent major surgery in our clinic from 1959 to 1998. 192 (31.8%) were male, 411 (68.2%) - female, age varying from 6 to 82 years; there were 29 (4.8%) children and adolescents, 210 (38.4%) adults aged 18-40, and 364 (60.4%) were older than 40. 40 (6.6%) patients presented signs of mediastinal compression: thoracic outlet syndrome in 2, superior vena cava syndrome in 30, marked airway compression in 12, and other signs - in 2. 64.5% patients with thymic masses presented generalized myasthenic syndrome, being of severe grade in more than a half cases. Origination of mediastinal masses is presented in Table 1.

Diagnostic algorythm included 3-plan chest X-ray, multiplan chest roentgenoscopy, pneumomediastinography, and pneumomediastinotomography; since 1990, the last two methods were completely replaced by computed tomography and magnetic resonance imaging.

Anaesthesia in all cases was endotracheal narcosis. Surgical access was usually chosen depending on mass localization. Retrosternal (mediastino-cervical) goiter was successfully removed through standard cervical approach in the majority (89.1%) of cases. Parasternal lipomas were removed as a rule through transrectal approach with dilatation of Larrey's fissura. Overall, 262 (43.4%) median sternotomies, 181 (30.0%) thoracotomy, 89 (14.8%) cervical, and 71 (11.8%) other approaches were used.

408 (67.7%) masses appeared to be benign or noninvasive, 195 (32.3%) - malignant or invasive. Invasion of 1 - 9 adjacent organs and structures was detected in 134 (22.2%) cases; in 49 of them, overall of 82 great vessels (66 veins, and 16 arteries) was revealed.

In 550 cases, radical surgery was performed, including 120 (19.9%) extended and 45 (7.5%) combined thymectomies, 47 (7.8%) other combined procedure, and 338 (56.0%) radical removal of masses without resection of adjacent organs and structures. 36 (6.0%) patients underwent surgical mediastinal decompression (excision of the most part of a tumour preserving some invaded adjacent organs), and in 17 (2.8%) only exploration and biopsy was performed. In 3 patients, combined surgery included bilateral phrenic nerve resections.

In 19 (38.8%) of 49 patients with great vessel invasion, overall of 6 superior venae cavae and 17 brachiocephalic veins were resected during combined procedures. In 6 of them, resected veins were reconstructed with polytetrafluorethylene grafts (in one case, brachiocephalic vein was replaced with transposed azygos vein). 24 (49.0) patients underwent decompressive surgery, and 6 (12.2%) - only exploration.

14 (35.0%) of 40 patients with signs of mediastinal compression underwent radical surgery, 21 (52.5%) - decompressive one, and 5 (12.5%) - exploration.

RESULTS. There were 42 (7.0%) postoperative complications; postoperative mortality made up 3.0% (18 patients). Morbidity and mortality after different kinds of surgery is presented in Table 2. There were no thromboembolic complications after prosthetic replacement of great veins.

Overall, the highest morbidity and mortality rate was seen after explorative surgery, the lowest - after radical removal of benign masses and malignant tumours without invasion of adjacent structures. In patients with invasion of adjacent structures, mortality and morbidity were slightly above median rates. Morbidity and mortality rates after combined surgery were comparatively higher than after decompression. The same correlations are present in the groups of patients with great vessel invasion and with mediastinal compression: morbidity and mortality are the highest after explorative surgery, being the lowest after decompressive one. Morbidity in cases with blood vessel prosthetic reconstruction was slightly higher than in vessel resections without reconstruction, mortality in these groups being similar.

Among 63 patients operated for mediastinal lymphoproliferative diseases, overall mortality and morbidity rates exceed median ones; yet, there was no mortality and minimal morbidity after simple and extended radical surgery and after decompression. Morbidity and mortality rate after explorative and combined surgery in lymphomas appeared to be comparatively high.

3 patients who survived bilateral phrenic nerve resection experienced transitory respiratory insufficiency which demanded artificial lung ventilation for 12 days postoperatively in 1 of them, but there was no mortality.

There were no cases of thrombosis of blood vessel grafts 3 - 18 months after great vein reconstruction.

DISCUSSION. According to our experience presented above, the worst option in mediastinal tumours invading adjacent organs and structures (especially great vessels) and/or complicated with mediastinal compression seems to be explorative surgery. At the same time, surgical decompression is possible in these cases with minimum of risk. So, we believe that, once the chest is opened in a case of mediastinal tumour, it should not be closed without at least prominent mediastinal decompression, if radical removal can't be performed.

We are fully agreed with those authors who consider that the use of prosthetic great vessel replacement in their tumourous occlusion is warranted by immediate and complete elimination of venous block and associated symptoms, which brings quick and marked relief of patients' condition, even if radical surgery can't be performed (2). In respect of comparatively low mortality and morbidity risk, we suppose that prosthetic replacement of invaded great mediastinal veins should be a routine stage of radical and decompressive surgical procedures in invasive mediastinal neoplasms.

Severe airway compression by mediastinal masses complicated by respiratory failure presents an extremely dramatic situation and a number of difficult strategic questions. Tracheobronchial stenting which pretends to become a standard procedure for these patients (3, 4) is reported to be accompanied by mortality rate up to 7% (4). As we have mentioned above (see Table 2), decompressive surgery may be performed in these cases with less mortality, to say nothing of benefits of total or subtotal tumour removal - intoxication decrease, facilitation of chemo- and radiotherapy, and some others.

Despite general sceptical attitude to surgical removal of mediastinal lymphomas, our results present us some reasons to agree with few advocates of surgery for these patients. In our opinion, this kind of surgery may well be performed without mortality and with minimal morbidity provided the choice of surgical extent is accurate and careful. Benefits of removal of mediastinal lymphomas are not only immediate mediastinal decompression, prevention of respiratory and thromboembolic complications, facilitation of consecutive specific chemo- and radiotherapy, but also providing plenty of pathological material for all kinds of examinations and investigations, which, in a certain number of cases, may be significant for accurate diagnosis. Importance of defining the role of surgery in treatment of lymphomas is underlined by reports regarding low sensitivity of a number of patients to chemotherapy (5, 6) and associated risks of great vein thrombosis and pulmonary embolism (7).

At the best of our knowledge, there are no reports of survival after bilateral phrenic nerve resection. We suppose that 3 our patients who did survive had bilateral phrenic nerve conductivity severely impaired for some time prior to surgery, due to nerve invasion, so that they were adapted to respiration by means of accessory respiratory musculature alone.

CONCLUSIONS. Significant number of mediastinal neoplasms are malignant or invasive. Mediastinal masses always bear potential risk of mediastinal compression; thus, surgery is indicated in all. In cases of invasion of adjacent organs and structures, especially great vessels, and in mediastinal compression, decompressive surgery is the most safe option, simple exploration being the most dangerous. Indications and counter-indications for combined radical surgery in advanced mediastinal tumours need further investigations and adjustment. Replacement of invaded great veins with polytetrafluorethylene grafts immediately relieves the symptoms of venous block, is not accompanied by specific complications, and should become a routine stage of radical and decompressive surgery of advanced invasive mediastinal neoplasms. Major surgery of mediastinal lymphomas has a number of benefits and may be performed without mortality and with minimal morbidity when detecting surgical extent accurately and carefully. Bilateral resection of invaded phrenic nerves does not lead to fatal respiratory failure and may be performed if needed.


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  TABLE 1. Origination of mediastinal masses.
 

Type of mediastinal mass

Number of cases

%

Thymomas

154

25.5

Germ cell tumours

15

2.5

Cysts

94

15.6

Neurogenic tumours

28

4.6

Lymphoproliferative diseases

63

10.4

Lipomas

87

14.4

Thyroid gland diseases

106

17.6

Others

56

9.3

TOTAL

603

100.0

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TABLE 2. Morbidity and mortality after different kinds of surgery.
 

Kind of surgery

Patients

%%

Morbidity

%%

Mortality

%%

Total

603

 

42

7.0

18

3.0

Simple and extended radical 

458

76.0

19

4.1

3

0.7

Combined

92

15.2

15

16.3

9

9.8

Decompressive

36

6.0

3

8.3

2

5.6

Explorative

17

2.8

5

29.4

4

23.5

 

 

 

 

 

 

 

Invasion of adjacent structures 

134

22.2

21

15.7

13

9.7

Combined

92

68.7

16

17.4

9

9.8

Decompressive

31

23.1

2

6.5

1

3.2

Explorative

11

8.2

3

27.3

3

27.3

 

 

 

 

 

 

 

Invasion of great vessels 

49

8.1

12

24.5

8

16.3

With graft replacement

6

12.2

2

33.3

1

16.7

Without graft replacement

13

26.5

3

23.1

2

15.4

Decompressive

24

49.0

4

16.7

2

8.3

Explorative

6

12.2

3

50.0

3

50.0

 

 

 

 

 

 

 

Mediastinal compression

40

6.6

6

15.0

5

12.5

Simple and extended radical 

5

12.5

0

0.0

0

0.0

Combined

9

22.5

3

33.3

2

22.2

Decompressive

21

52.5

1

4.8

1

4.8

Explorative

5

12.5

2

40.0

2

40.0

 

 

 

 

 

 

 

Mediastinal lymphomas

63

10.4

5

7.9

4

6.3

Simple and extended radical 

18

28.6

1

5.6

0

0.0

Combined

24

38.1

3

12.5

3

12.5

Decompressive

13

20.6

0

0.0

0

0.0

Explorative

8

12.7

1

12.5

1

12.5

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