Introduction:
Subclavian artery aneurysm is a very rare aneurysm, comprising of 1% of all peripheral aneurysms. The most prevalent aetiology of a subclavian artery aneurysm is atherosclerosis, which accounts for approximately 60% of reported cases. Other causes include trauma, thoracic outlet syndrome, and infection.

Aim:
To present an atypical presentation of an acute, enlarging subclavian artery aneurysm as a midline neck mass, causing respiratory distress and dysphagia and the subsequent diagnostic possibilities.

Case study:
We present a case involving a 50-year-old male who presented with a sudden, large, midline neck swelling, causing shortness of breath, hoarseness, and dysphagia, in the background of severe hypertension and chest pain.

Results and discussion:
Chest radiograph revealed widening of the mediastinum, suggesting an aortic aneurysm or a mediastinal mass. Computed tomography (CT) of neck and thorax was planned, but the patient’s condition deteriorated in the attempt to lie flat prompting an emergent intubation procedure to secure his airway. Contrast-enhanced CT neck and thorax, with angiography was done. The scan demonstrated a proximal right subclavian artery aneurysm measuring 6.0 × 6.0 × 7.2 cm. The final diagnosis of a right subclavian artery aneurysm was made.

Conclusions:
(1) Diagnosis of arterial aneurysm should be considered in an acute midline neck mass, especially in middle-aged men with severe hypertension and chest pain. (2) CECT neck and thorax, with angiography is useful to evaluate the origin, size and extent of the lesion, supporting the diagnosis of subclavian artery aneurysm. (3) In acute airway emergency, caution should be taken to perform tracheostomy as it would cause rupture of the aneurysm.