X-ray
What is the likely cause?
Thoracic aortic aneurysm (TAA) as the patient has no history of recent trauma or pain (ddx: haematoma; dissection).
Are there any other clues on the image that might increase the likelihood of a thoracic aortic aneurysm?
Partially imaged abdominal stent graft. ~25% of patients with TAA will have an AAA.
Widening of descending thoracic aorta shadow. Abdominal aorta stent graft partially imaged. Stable left lower zone atelectasis. No focal consolidation to suggest pneumonia. Heart size is normal.