Chest x-ray abnormalities

Mediastinal abnormalities

Mediastinal widening

Widening of the mediastinum is most often due to technical factors such as patient positioning or the projection used. Rotation, incomplete inspiration, or an AP view, may all exaggerate the width of the mediastinum, as well as heart size.

In the setting of trauma, patients are positioned supine while a chest x-ray is acquired, very often causing the mediastinum to appear wide spuriously.

Mediastinal masses and vessels

If a PA standing chest x-ray has been taken with good inspiration and no rotation, any widening of the mediastinum is likely to be genuine. The main pathological causes to consider include masses and widening of vessels.

Key points

  • A widened mediastinum is often due to technical factors
  • Genuine widening is usually due to a vascular abnormality or a mediastinal mass
  • A lateral view may help determine the location of a mass
Hover over image to show findings

Mediastinal mass

  • Wide upper mediastinum (arrowheads)
  • Poorly defined aortic knuckle - indicating adjacent disease
  • Wide right paratracheal stripe (*)
  • Normal lungs

Clinical information

  • Night sweats and weight loss
  • Palpable neck lymph nodes

Diagnosis

  • Hodgkin's lymphoma
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Locating masses within the mediastinum

A lateral view may help determine the location of a mediastinal mass. Usually a CT of the thorax is also performed.

Mediastinal mass - Lateral view
Hover over image to show findings
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Mediastinal mass - Lateral view (same patient)

  • Mass located in the anterior mediastinum - anterior to the heart

Diagnosis

  • Hodgkin's lymphoma

Differential diagnosis of anterior mediastinal masses

  • Lymphoma
  • Thyroid enlargement
  • Teratoma
  • Tumours of the thymus

Mediastinal vessel enlargement

Enlarged vessels such as thoracic aortic aneurysms or congenital vascular anomalies may also cause mediastinal enlargement.

Hover over image to show findings
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Thoracic aortic aneurysm

  • Sternal wires and aortic valve prosthesis (arrowhead)
  • Massive aortic knuckle (red line)
  • Displaced trachea (arrow)
  • Widened, tortuous descending aorta (blue lines)

Clinical information

  • History of uncontrolled hypertension
  • Previous history of an episode of severe chest pain radiating to the neck and back

Diagnosis

  • Chronic thoracic dissecting aortic aneurysm - treated with surgical repair of the aortic root

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