Asian Cardiovasc Thorac Ann 2004;12:263-265
© 2004 Asia Publishing EXchange Ltd
Posterior Mediastinal Goiter
Chee-Fui Chong, FRCS,
Wei-Keat Cheah, FRACS1,
Fai-Lam Sin, FRCPI2,
Poo-Sing Wong, FRCS
Department of Cardiac, Thoracic and Vascular Surgery
1 Department of Surgery, National University Hospital, Singapore
2 Department of Medicine, Alexandra Hospital, Singapore
For reprint information contact: Chee-Fui Chong, FRCS Tel: 65 6772 2060 Fax: 65 6776 6475 Email: wongps{at}nuh.com.sg Department of Cardiac, Thoracic and Vascular Surgery, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Republic of Singapore.
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ABSTRACT
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Most mediastinal goiters are retrosternally situated in the anterior mediastinal compartment. Posterior mediastinal goiters, either retrotracheal or retroesophageal, are rare. We herein describe a case involving a retrotracheal goiter in the right posterior mediastinum, which was excised using a combined cervico-partial sternotomy and right thoracotomy approach.
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INTRODUCTION
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While the incidence of intrathoracic thyroid goiters is around 10–15% of all mediastinal masses, most are found in the anterior superior mediastinal compartment.1,2 Posterior mediastinal masses, however, are commonly of neural origin and those arising of thyroid tissue are rare.3 Diagnoses are usually based on cytological analysis.3 The following describes a case of a posterior mediastinal goiter diagnosed with ultrasound control fine needle aspiration cytology (FNAC), which was later resected completely using a combined cervico-partial sternotomy and right thoracotomy approach.
A 63-year-old Chinese man presented with a one month history of productive cough without dyspnoea, hemoptysis, dysphonia or dysphagia. He had lost 2 kg in body weight in the previous month. He was an ex-smoker and was on treatment for hypertension. Chest radiograph showed a large superior mediastinal mass. Computed tomography scan confirmed a 13 x 8 cm posterior mediastinal mass extending from the lower border of the left lobe of the thyroid gland (Figure 1A
) to beyond the level of the carina. It was retrotracheal with displacement of both trachea and oesophagus laterally towards the right. Ultrasound guided FNAC was performed through a suprasternal approach and showed features suggestive of thyroid tissue. Clinically he was euthyroid and thyroid function tests were normal.
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Figure 1. CT scan (A) shows substernal view of the retrotracheal goiter originating from the inferior pole of the left thyroid lobe (arrow), (B) the large dumbbell shaped retrotracheal goiter (arrow) with right lateral deviation and posterior compression of the trachea to a slit-like opening.
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The patient was therefore planned for resection of the tumor through thoracotomy and cervical approach. Rigid bronchoscopy showed the trachea to be deviated towards the right. There was extrinsic compression of the entire length of the trachea with slit-like lumen and no endobronchial abnormalities (Figure 1B
). As the mass was mainly located in the right posterior mediastinum, a right thoracotomy via the 5th intercostal space was performed. A frozen section of the tumour was obtained which confirmed a benign thyroid nodular goiter. The tumor was dissected free of the surrounding structures but was found to be connected to the left thyroid lobe. The thoracotomy was closed and the patient turned to supine position. Through a cervical incision with partial upper sternotomy extension, a subcapsular thyroid dissection was performed since the retrotracheal position of the goiter prevented proper identification of the left recurrent laryngeal nerve. However, because of its dumbbell shape (Figure 1B) in the mediastinal portion, the entire tumor could not be delivered out from the cervico-partial sternotomy incision. The entire goiter, measuring 13 x 8 x 8 cm, was finally delivered through the right thoracotomy incision. In the process of dissection, the right posterior tracheal membrane was breached. This 2 cm longitudinal laceration was successfully repaired using a 3/0 prolene interrupted suture. The trachea was then tested with ventilation to 40 cm of water pressure and found to be airtight. The patient was ventilated for 24 hours and extubated the next day. Flexible bronchoscopy through the endotracheal tube did not show any tracheomalacia. The remaining postoperative course was uneventful and the patient was discharged fit and well 8 days later. He did however complained of hoarseness of voice at 2 weeks follow-up and subsequent laryngoscopic examination confirmed a paralysed left vocal cord. He remains well at 4 months follow-up despite his hoarse voice.
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DISCUSSION
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The incidence of intrathoracic thyroid goiter is reported to be around 10–15% of all mediastinal masses.1 Of these, the majority (75–95%) are anterior substernal extensions, located anterior to the recurrent laryngeal nerve and the great vessels.1,2 Posterior mediastinal goiters constitute only 4% of all posterior mediastinal masses and 10 to 25% of all intrathoracic goiters.2 Most posterior mediastinal goiters are found in the right mediastinum irrespective of the thyroid lobe of origin. This is probably due to the presence of the aortic arch and pulmonary vessels, which obstruct the descent of left sided goiters into the left mediastinum.2 Extension from the right thyroid lobe tends to descend behind the recurrent nerve, right inferior thyroid artery, right subclavian vessels and superior vena cava (SVC).2 Left lobe goiter descends through the tracheooesophageal plane, displacing the trachea and osophagus towards the right.2 The case we have described here is best represented by the diagram shown in Figure 2 with a large mediastinal but normal cervical component.
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Figure 2. Schematic representation of the large goiter originating from the inferior pole of the left thyroid lobe and passing between the trachea and the oesophagus into the right posterior mediastinum with right lateral deviation of the trachea.
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As with our case, the dominant clinical presentation is one of compressive symptoms (60%) with 4% of patients wrongly diagnosed as having bronchial asthma due to compression of the trachea.1 Dysphagia and superior vena cava syndrome were reported in 4 to 12% of cases.1,4 The majority of patients are euthyroid with only 11% presenting with hyperthyroid symptoms.1 Forty percent of patients are asymptomatic and the intrathoracic mass discovered incidentally on chest radiographs.1 Computed tomography scans are essential to define the size, structure and relationships to mediastinal structures. Definitive diagnosis is made using either radiological guided FNAC or surgical procedures such as video-assisted thoracoscopic guided biopsy. Once diagnosis is made, most intrathoracic goiters should be removed since growth of these tumors can lead to displacement or compression of surrounding structures and organs. The majority (70%) can be removed through a cervical incision alone but in 22% of cases, an additional sternotomy may be required while the remaining 8% requires thoracotomy.1,2,5 Posterior mediastinal goiter with contralateral extensions, however, are best removed via a combined cervical-thoracotomy approach.2 As in our case, which had a large contralateral dumbbell shaped mediastinal component, delivery through a cervical incision was not possible. Therefore, once the left thyroid lobe was dissected free through a cervico-partial sternotomy incision, the tumor had to be delivered out through the right thoracotomy incision.
Care must be taken to avoid injury to important surrounding structures such as the recurrent laryngeal nerves, trachea, osophagus and thoracic duct. In this case, a nasogastric tube was inserted after induction of anesthesia to allow identification of the esophagus during dissection. As the goiter was pushing the trachea anterolaterally and with a thin posterior membrane, even with careful dissection, a longitudinal tear was inadvertently made. This was repaired uneventfully. The right recurrent laryngeal nerve was located higher than the plane of dissection and thus was not injured. Due to the retrotracheal position of the tumor, both the left recurrent laryngeal nerve and thoracic duct was abnormally displaced, making identifying both structures difficult. We therefore resorted to a subcapsular dissection of the left thyroid lobe in order to avoid injury to these structures. However, despite this manoeuvre, the left recurrent laryngeal nerve was injured as our patient developed post operative dysphonia and was confirmed to have paralysis of the left vocal cord on laryngoscopy.
In conclusion, management of posterior mediastinal goiter requires a combined surgical approach of both general surgeons and cardiothoracic surgeons once diagnosis is confirmed. Care must be taken to avoid injury to surrounding structures such as the trachea, esophagus and recurrent laryngeal nerves.
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REFERENCES
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- Vadasz P, Kotsis L. Surgical aspects of 175 mediastinal goiters. Eur J Cardiothorac Surg
1998;14:393–7.
- Shahian DM, Rossi RL. Posterior mediastinal goiter. Chest
1988;94:599–602.[Abstract/Free Full Text]
- Van Schil P, Vaneerdeweg W, Schoofs E, Abs R. Retrotracheal mediastinal goiter with contralateral extension. Ann Thorac Surg
1989;48:889–90.[Medline]
- Silverstein GE, Burke D, Goldberg D, Halko A. Superior vena caval system obstruction caused by benign endothoracic goiter. Dis Chest
1969;56:519–23.
- Haniuda M, Morimoto M, Kobayashi O, Nishimura H, Yamanda T, Ali K et al. Aberrant retrotracheal goiter: report of a case. Surgery Today
1993;23:149–52.[Medline]
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ABSTRACT
INTRODUCTION
