Why the alveolar opacities?

Labs and Lytes 025

Author: Chris Sia
Reviewers: Sarah Yong and Chris Nickson

A 30 year-old lady presents with acute type 1 respiratory failure and fever

Click image to enlarge

Click image to enlarge

Q1. Describe the x-ray findings?

This is an AP supine CXR.

The most striking findings are bilateral alveolar opacities in the upper zones and a confluent opacity in the right middle and lower zones.

Other features:

  • Right internal jugular central line
  • Intubated
  • Nasogastric tube (difficult to determine if adequately positioned on this image)
  • Obscuration of the right heart border and preservation of the diaphragm suggests RML involvement

Q2. What are the causes of alveolar (airspace) opacities?

Causes include:

  • Fluid: cardiogenic and non-cardiogenic pulmonary oedema, ARDS, aspiration
  • Pus: Pneumonia (bacterial, atpical, fungal, viral, parasitic)
  • Blood: Trauma (contusion), immunological (Goodpasture’s syndome), bleeding diathesis (coagulopathy), pulmonary embolism
  • Protein: Alveolar proteinosis
  • Cells: Adenocarcinoma in situ (bronchoalveolar cell cancer), lymphoma

Alveolar or airspace abnormalities implies different undlerlying causes to interstitial opacities.

Q3. What are the differentials of interstitial opacities?

Upper zone: SCART

  • Silicosis/Sarcoidosis
  • Coal workers pneumoconiosis
  • Ankylosing spondylitis, allergic bronchopulmonary aspergillosis
  • Radiotherapy
  • Tuberculosis

Lower zone: RASIO

  • Rheumatoid arthritis and other connective tissue diseases
  • Asbestosis
  • Scleroderma
  • Idiopathic pulmonary fibrosis
  • Other: Drugs (eg methotrexate, amiodarone, bleomycin, hydralazine, amiodarone, nitrofurantoin, busulphan)

In general, inhalational pathologies involve the upper zone, whereas many systemic (‘blood-borne’) pathologies involve the lower zones

References and links

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