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Ann Thorac Surg 2004;78:987-991
© 2004 The Society of Thoracic Surgeons
a Division of General Thoracic Surgery, University Hospital Berne, Bern, Switzerland
b Division of Radiology, University Hospital Berne, Berne, Switzerland
Accepted for publication March 25, 2004.
* Address reprint requests to Dr Weber, Division of General Thoracic Surgery, University Hospital Berne, Freiburgstrasse, CH-3010 Berne, Switzerland
thomas.weber{at}insel.ch
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Abstract |
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METHODS: Between June 1995 and December 2002, a nonselected series of 12 consecutive patients presenting with mediastinal bronchogenic cysts underwent video-assisted thoracoscopic surgery. Six cysts (50%) had been diagnosed 2 to 22 years prior, only three of which became symptomatic. In asymptomatic patients (n = 7) surgery was performed because of increasing cyst size (n = 3), patient's request (n = 3), or suspected metastasis (n = 1).
RESULTS: Mediastinal bronchogenic cysts were correctly diagnosed by computed tomography in 83% (10/12) and by magnetic resonance imaging in 100% (9/9). Using a three-trocar technique thoracoscopic surgery was successfully performed in 11 of 12 cases (92%). We noted no signs of acute cyst infection. No serious postoperative complications were observed. In 1 patient conversion to open thoracotomy was necessary due to extensive pleural adhesions. In another case thoracoscopic excision of the cyst wall was incomplete. Patients with thoracoscopic excision were discharged after a median of 5.5 days (range 4 to 14 days). No recurrences or complications were observed during a mean follow-up of 40.5 months.
CONCLUSIONS: Considering the low conversion and complication rate in our series, video-assisted thoracoscopic surgery should be the primary therapeutic choice among adults with symptomatic mediastinal bronchogenic cysts. Surgical intervention in patients with asymptomatic and uncomplicated cysts appears optional.
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Introduction |
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Although chest pain, cough, dyspnea, dysphagia, hemoptysis, infection, or other nonspecific symptoms may lead to diagnosis [2–7], many mediastinal bronchogenic cysts (MBC) are encountered incidentally during routine chest roentgenogram for other reasons. Thus a considerable proportion of asymptomatic cysts will remain undetected and the true incidence of this rare anomaly and the significance of nonspecific clinical symptoms are elusive. However, once the condition is diagnosed surgical excision is frequently indicated, either to relieve clinical symptoms, remove an enlarging cyst, or prevent possible complications, such as cyst infection, malignant transformation, tracheal compression, superior vena cava syndrome, or hemoptysis [2, 4, 8–10].
The excision of a bronchogenic cyst by video-assisted thoracoscopic surgery (VATS) was first reported by Mouroux and associates in 1991 [11]. Since then some case reports or small series have been published [4–6, 12–14]. So far the reported conversion rate to open thoracotomy ranges between 0% and 35% [15, 16]. The objectives of this study were to outline our single-center experience and to further assess the appropriateness of VATS for the treatment of MBC in adults. Therefore all patients presenting with this rare diagnosis during a 7.5-year period were retrospectively analyzed with regard to clinical symptoms, indications for surgery, and results of intended VATS.
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Material and methods |
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Overall surgery was indicated because of clinical symptoms (n = 5), increase in cyst size (n = 3), patient's request (n = 3), or histologic clarification of an unidentified mediastinal tumor suspicious for a metastases (n = 1). All patients were underwent preoperative chest roentgenogram and computed tomography (CT) (Fig 1). In 9 patients a magnetic resonance imaging (MRI) (Fig 2) was also performed. Three gastroscopies and two bronchoscopies were obtained preoperatively to exclude a communication with the esophagus or the tracheobronchial tree. An extrinsic compression of the esophagus was documented by barium passage in 1 patient and lung sequestration was excluded by angiography for another patient. In 1 patient an increasing cyst size was observed 19 years after diagnostic fine needle aspiration, in which a malignant transformation of a MBC, diagnosed by CT, was excluded.
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Histology
The histologic examination of all retrieved specimens confirmed the diagnosis of benign bronchogenic cysts with the typical feature of a ciliated columnar epithelial lining. Chronic inflammation with a thickened cyst wall was seen in three cases and cartilaginous tissue within the cyst wall in two cases. None of the patients had clinical or histologic evidence of an acute infection or inflammation of MBC. The levels of C-reactive protein were normal in 11 patients and slightly elevated in 1 patient.
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Results |
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With regard to the diagnostic approach MRI appeared to be superior to CT. In all patients in whom MRI was performed (n = 9), the correct diagnosis was achieved preoperatively. Most cysts (n = 7) showed low or moderate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The cysts in the other 2 patients who underwent MRI showed high signal intensity in T1-weighted images and low signal intensity in T2-weighted images.
Computed tomography scans were performed in all 12 patients and were indicative for MBC in 10 patients (83%). Computed tomography density either varied between 30 and 56 Hounsfield units (n = 4) or was characterized as a cystic (n = 5), semiliquid (n = 2), or tumorous lesion (n = 1). Of the 2 patients in whom CT scans were not conclusive, 1 patient was admitted to the hospital after a car accident with a blunt chest trauma. In the initial CT scan, performed under emergency conditions, a mediastinal mass was interpreted as hemorrhage. A control MRI after 3 days revealed a mediastinal cyst; elective surgery was performed thereafter. In another patient with a history of laryngeal carcinoma a 2-cm solitary nodule in the anterior mediastinum was detected by CT (Fig 1). No further evaluation with MRI was done. The VATS was performed after this nodule was deemed to be an unidentified mediastinal tumor, in assumption of a lymph node metastasis.
With the exception of one cyst found within the anterior mediastinum (Fig 1), all other cysts were located in the posterior compartments of the mediastinum, seven (58%) on the left side and four (33%) on the right side, respectively (Fig 3). Cyst size, that is, maximal diameter, varied between 2.0 and 6.6 cm.
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Five cysts were intentionally or accidentally opened during VATS, but thoracoscopic excision proceeded nonetheless. In one case cystic fluid was aspirated at the beginning of surgery and in another case cyst excision was incomplete because of severe adhesions to the left vagus and recurrent laryngeal nerves. The postoperative course was uneventful in all cases and the 11 patients who underwent VATS were discharged after a median of 5.5 days (range 4 to 14 days). One patient who underwent VATS was hospitalized for 14 days because of postoperative diarrhea of unknown origin; the patient who underwent open thoracotomy had an in-hospital stay of 9 days. After a follow-up of 3 to 90 months (mean 40.5 months, median 25 months) no recurrences or late complications were observed.
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Comment |
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Conversion to open thoracotomy is mainly related to major pleural adhesions [4, 15], as was the case in our study. A cyst may also open during VATS. In our experience this occurrence does not interfere with the proceeding of thoracoscopic surgery. Hazelrigg and associates [16] proposed a deliberate aspiration of the cyst early during thoracoscopy to facilitate handling and preparation of the cyst. We generally prefer to aspirate cystic fluid at the completion of surgery before extracting the cyst. In our hands an intact cyst facilitates the thoracoscopic dissection along the layers.
When cysts adhere to vital structures surgical excision may be incomplete, leaving portions of the cyst wall in situ [6, 8, 15, 16]. In those cases destruction of mucosal lining by electrocautery may help to avoid cyst recurrences [6, 17]. Nevertheless complete excision should always be the primary intention, as late recurrences, even after 25 years, have been described after incomplete excision [18, 19]. In this study argon beam ablation of residual cystic epithelium was applied without recurrence after 12 months in one case, but this single observation does not allow any further conclusions to be made about this management. Incomplete cyst excision is not confined to VATS but has also been described after open surgery [2, 4, 6, 8, 15].
The reported incidence of clinical symptoms in patients with MBC varies between 9.1% and 67% [2–6]. In this series physical complaints could be objectified in 42% of our patients, with no significant difference between known and newly diagnosed MBC. Today the indication for surgical treatment of adult patients with symptomatic MBC is generally accepted, although the relationship of small MBC to nonspecific symptoms such as chest pain or cough frequently remains questionable [20].
The management of asymptomatic cysts is under controversial discussion, particularly because the malignant transformation of MBC in adults has been questioned [21]. Although some clinicians accept a conservative management with continued observation in asymptomatic patients [21, 22], others recommend that all presumed bronchogenic cysts should be resected because the majority will ultimately become symptomatic or complicated [2, 3]. Our results, perhaps due to the small number of patients, neither support nor contradict any final conclusion, although all 6 patients with known cysts had been observed between 2 and 22 years without developing any cyst-related complications. Only 3 of those patients had mild symptoms. Similar cases were reported in the literature [4]. Thus, to us, there appears to be no urgent need for surgery in asymptomatic patients, provided that a simple MBC has been clearly diagnosed. However, if a complicated cyst, for example with fistulization to the airways, is suspected, surgery should be performed in asymptomatic patients as well.
In our experience asymptomatic patients, sometimes influenced by others, frequently request surgical intervention because of fear of malignancy, an enlarging cyst, or other possible complications. No less than half of our patients were operated on because of that reasoning. A rational argument can be made, however, that surgical intervention can be limited to patients with clearly symptomatic or suspected complicated MBC.
A precise preoperative evaluation is mandatory for any successful thoracoscopic approach. With the help of CT we were able to correctly diagnose bronchogenic cysts in 83% of our patients, which compares favorably to the 62% to 100% accuracy reported in the literature [3, 5, 6, 13, 14]. Magnetic resonance imaging further enhanced the diagnostic accuracy to 100% in this series and may provide additional information that is not available by other noninvasive imaging techniques [6, 13, 23]. In our study a posttraumatic lesion considered to be mediastinal hemorrhage according to CT findings was subsequently diagnosed as a MBC through the use of MRI. Similar experiences were reported by Kanemitsu and associates [6]. Depending on proteinaceous material or blood inside the cyst, MRI appearance varies on T1- and T2-weighted images [6, 23], which was confirmed in our study. The endoscopic transesophageal ultrasound may provide additional information on the relation of MBC to adjacent structures [13, 24]. However, because endoscopic ultrasound is an invasive diagnostic tool, we think that the procedure should be reserved for those few patients in whom CT and MRI are inconclusive or in whom an esophageal duplication cyst with communication to the esophagus is suspected.
In conclusion, modern imaging techniques and the increasing experience with thoracoscopic surgery may help to change the surgical attitude toward patients with MBC. Today MRI is highly accurate in diagnosing simple MBC. As a result it is the preferred imaging modality for patients with already suspected MBC on chest roentgenogram at our institution. After definite diagnosis has been achieved asymptomatic MBC can be managed conservatively, provided that a complicated cyst has been excluded. However, the intraoperative difficulties and postoperative results of VATS in this study compared favorably with known results of open surgery from current literature. Thus, considering the known advantages of minimally invasive surgery [25], we advocate VATS as the approach of choice in patients with symptomatic MBC.
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  O. N. Pages, S. Rubin, and B. Baehrel Intra-esophageal rupture of a bronchogenic cyst Interactive CardioVascular and Thoracic Surgery, August 1, 2005; 4(4): 287 - 288. [Abstract] [Full Text] [PDF]
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