Surgical resection
Surgical decisions were guided using an institutional treatment algorithm (Figure 1). If extracervical access was not necessary, patients were managed using a cervical approach only through digital dissection and upwards traction of the goiter. Where an extracervical approach was indicated, surgical management was guided by the extent and direction of inferior extension. Anterior goiters above the level of the pericardium were resected using cervical thyroidectomy with either mediastinoscopic-assisted delivery or cervical thyroidectomy with video- assisted thyroidectomy (VATS). Those extending beyond the pericardium instead required median sternotomy to facilitate sufficient vascular control and exposure. Goiters extending into the posterior mediastinum were managed using trans-thoracic approaches, this time via the posterolateral route such as a lateral thoracotomy or VATS.

Results

Case one

A 59-year-old male presented with an enlarged neck mass and voice changes. CT imaging revealed an enlarged thyroid gland with retrosternal extension to T4 in contact with, but not beyond, the aortic arch in the anterior mediastinum (Figures 2a and 2b). He underwent a total thyroidectomy via Kocher’s incision where the strap muscles were divided, and the thyroid gland was mobilised using subcapsular dissection technique. The superior, lateral, posterior, and much of the inferior poles of the thyroid gland were freed using forceps dissection before upward traction applied to the superior poles delivered the gland’s mediastinal component (Figures 2c and 2d). The patient had an uneventful recovery and was discharged on postoperative day two. The final histology confirmed benign nodular hyperplasia.

Case two

A 59-year-old female presented with dysphagia and a CT scan demonstrating an enlarged thyroid gland with an anterior mediastinal component connected via a fibrous stalk. Total thyroidectomy was performed as described in case one, however, the fibrous stalk did not allow for traction delivery of the mediastinal component. Instead, the stalk was amputated, the cervical goiter was delivered via the neck incision, and the remaining mediastinal component was removed with an extracervical approach using VATS.
The right lateral chest wall and the upper abdomen were exposed, and the patient was tilted slightly to the left before the anaesthetist inserted and inflated a blocker into the right mainstem bronchus. Three ports were inserted along the inframammary line and one port was inserted through the anterior chest after deflation of the lung. The pseudocapsule around the goiter was dissected free and the feeding vessels were ligated. The goiter was then delivered via one of the thoracic ports in an endopouch. The final histology demonstrated benign nodular hyperplasia for both lesions.

Case three

A 76-year-old female presented with right heart failure and pleural effusion secondary to a retrosternal goiter in the anterior mediastinum compressing upon the right heart, thus necessitating resection using a transcervical-sternotomy approach (Figure 3a and 3b). A low collar incision was made in continuity with the median sternotomy wound which was carried down to the xiphoid process before sternal retraction was applied (Figure 3c). The mediastinal component of the goiter was mobilised and freed up to the aortic arch and multiple feeding vessels from the mediastinum were ligated. The cervical component was mobilised as described in case one. After full mobilisation superiorly and identification of both recurrent laryngeal nerves, the pleura was opened superiorly, and bilateral phrenic nerves were identified. At this point, the retrosternal goiter was progressively removed from the superior mediastinum en bloc with full visualisation of both the recurrent laryngeal nerves and phrenic nerves(Figure 3d). On follow-up, the patient demonstrated normal vocal cord movement bilaterally, intact parathyroid gland function, and resolution of the symptoms from right heart failure. Her final histology confirmed a multinodular goiter.

Case four

A 68-year-old female with a history of retrosternal goiter treated with iodine ten years prior presented with a large right-sided thyroid mass. Fine needle aspiration suggested a diagnosis of papillary thyroid cancer and her repeat CT scan confirmed an enlarged thyroid gland with cystic retrosternal extension into the posterior mediastinum, adherent to surrounding mediastinal structures. Total thyroidectomy was performed as described in case one. The isthmus was divided, and the left lobe was removed. Transcervical digital dissection of the retrosternal component was performed as much as possible, and the right thyroid lobe was pedicled on the retrosternal component (Figure 4a).
The remaining retrosternal component was removed with VATS. The goiter was visualised in the posterior mediastinum and an incision was made on the pleura (Figure 4b ). The azygous vein appeared adherent to the goiter and was subsequently ligated with an Endo-GIA stapler. The tumour was mobilised with endoscopic Ligasure. It was freed from the trachea and continued circumferentially up to the level of the thoracic inlet (Figure 4c). The goiter was subsequently delivered through the neck, attached to the right hemithyroid (Figure 4d ). The patient had an uneventful recovery and was discharged on postoperative day three. Final pathology confirmed a five-centimetre papillary thyroid cancer with clear margins.

Discussion

Our institutional algorithm firstly involves determining whether an extracervical approach is warranted. Approximately 95% of retrosternal goiters can be removed cervically through the neck incision using upward traction, digital dissection, and with assistance of long instruments (case one ).6 However, some cases necessitate a concurrent extracervical approach (Figure 1) . Adequate exposure is challenging with a cervical approach in goiters extending below the aortic arch or carina or situated within the posterior mediastinum.7Similarly, an extracervical approach is necessary for vascular control where the goiter has blood supply originating from mediastinal vessels or for safe resection where no tissue plane between it and surrounding tissues can be identified on CT.8 Finally, upward traction in the cervical approach may be difficult in patients with thyroid tissue beyond easy reach via the neck incision, isolated primary or ectopic retrosternal goiters, or where the thoracic component connects to the cervical component via a fibrous stalk (case two ).9
Median sternotomy is the most common extracervical approach in the literature. Whilst this provides excellent exposure to anteriorly extending retrosternal goiters (case three ), it is associated with considerable morbidity and exposure to the posteriorly extending goiters remains limited by the heart and great vessels. Consequently, the lateral thoracotomy is instead often used for posterior retrosternal goiters due to better exposure and decreased morbidity.4
VATS and mediastinoscopic approaches are increasingly used in the treatment of retrosternal goiter (cases two and four ). In comparison to open thoracotomy, VATS has been shown to be associated with decreased postoperative pain, shorter hospital stay, improved postoperative pulmonary function.10 In our experience, these techniques may be utilised in cases where the retrosternal component extends to the aortic arch, but the surgeon is unable to obtain adequate vascular control for safe delivery of the lesion with cervical blunt dissection. This is particularly valuable as the tissue plane between the goiter and the pretracheal fascia, prevertebral fascia and the oesophagus is often described as quite dense, with transcervical approaches increasing the risk of inadvertent oesophageal tear or uncontrollable bleeding.

Conclusion

Although most retrosternal goiters can be removed transcervically, a small proportion of patients require concurrent extracervical approaches. Based on decades of experience in the surgical management of retrosternal goiters, a practical institutional algorithm has been presented to guide surgical planning in a complex field.