Thoracic extension of cervical goitre is usually approached through

Resection of retro sternal goitre can almost always be carried out from the neck, but median sternotomy is rarely necessary Characteristics that might predict an inability to mobilize a thoracic goiter into a cervical incision include a reoperative field, an invasive substernal thyroid malignancy, goiters that extend below the inferior margin of the aoic arch, goiters that reach the carina, goiters that extend into the posterior mediastinum, and true ectopic mediastinal thyroid tissue. Source : Sabiston 20th edition Pg : 918