Chest x-ray abnormalities

Hilar abnormalities

The hila consist of vessels, bronchi and lymph nodes. On a chest x-ray, abnormalities of these structures are represented by a change in position, size and/or density.

Hilar enlargement

Hilar enlargement may be unilateral or bilateral, symmetrical or asymmetrical. In combination with clinical information, each of these patterns is often helpful in reaching a diagnosis. Bilateral, symmetrical hilar enlargement should raise the suspicion of sarcoidosis, particularly if there is evidence of paratracheal enlargement, or lung parenchymal shadowing.

Key points

  • The left hilum is usually higher than the right
  • Check the size of the hila
  • Check the density of the hila
  • If a hilum is displaced, ask yourself if it has been pushed or pulled
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Bilateral hilar enlargement

  • Both hila are larger and denser than normal
  • A small degree of patient rotation is irrelevant in this case - the observation of bilateral, symmetrical hilar enlargement can still be made
  • Patchy bilateral lung parenchymal shadowing

Clinical details

  • Joint pain
  • Erythema nodosum

Diagnosis

  • Sarcoidosis

Differential

  • Lymphoma, metastatic disease or infection may occasionally look similar
  • Pulmonary arterial hypertension may also cause bilateral symmetrical hilar enlargement
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Asymmetric hilar enlargement

  • Both hila are larger and denser than normal
  • The right hilum is bigger than the left
  • Multiple small lung nodules
  • Missing right breast shadow (mastectomy)

Clinical details

  • Known breast cancer
  • Increasing shortness of breath

Diagnosis

  • Metastatic disease
  • Breast cancer

Hilar position

If a hilum has moved, you should try to determine if it has been pushed or pulled, just like you would for the trachea. Ask yourself if there is a lung abnormality that has reduced volume of one hemithorax (pulled), or if there has been increase in volume or pressure of the other hemithorax (pushed).

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Abnormal hilar position

  • The left hilum is large, dense and pulled laterally and upwards to the left
  • The trachea is deviated (pulled) towards the left, indicating loss of lung volume in the left hemithorax

Clinical details

  • History of left hilar malignancy treated with radiotherapy

Diagnosis

  • Radiation fibrosis

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