A 65 year old woman presented with acute stridor and breathlessness. She gave no prior history of respiratory symptoms and had no past medical history of note. Clinical examination was unremarkable with the exception of stridor and a moderate degree of respiratory distress. Her speech was normal. She had no palpable goitre. She was clinically and biochemically euthyroid.

Chest radiography revealed a superior mediastinal mass causing compression of the trachea and displacement to the right (fig 1). Subsequent mediastinal computed tomography (fig 2) confirmed the mass and suggested it as an extension of the left lobe of the thyroid gland. However, at operation a large ectopic goitre measuring 7.5 × 4.5 × 4 cm was resected by a cardiothoracic surgeon. It appeared that bleeding into the goitre had caused swelling and tracheal compression. The goitre was histologically benign.

Rarely, a mass in the anterior upper mediastinum may be a primary mediastinal goitre.¹ Substernal extension is a well recognised feature of goitre arising in the anatomical thyroid gland and respiratory symptoms of a chronic, progressive nature are common in such cases.² Sudden airway compromise caused by a goitre (ectopic or anatomical) rarely occurs but may necessitate immediate intubation.³

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Figure 1

Mediastinal mass causing tracheal displacement and compression.

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Figure 2

Comfirmatory evidence by computed tomography.