Alveolar sarcoidosis

Alveolar sarcoidosis is an atypical pulmonary manifestation of sarcoidosis

This appearance may be present in around 4% 1 of those with pulmonary sarcoidosis on plain film and up to 15% 2 of those on CT.

This appearance is thought to result from aggregation of large numbers of interstitial granulomas rather than representing a true alveolar process. Some authors have therefore applied a more appropriate term as "pseudoalveolar sarcoidosis".

CT/HRCT chest

There can be large areas of pulmonary opacification ranging in diameter from 1 to 4 cm. These can be rounded or elongated in shape, have irregular edges and blurred margins with or without air bronchograms. They are typically found either along the bronchovascular bundles or in the lung periphery adjacent to the pleural surface 3.

Small nodules around these large opacities is often termed the galaxy sign

Another pattern of alveolar sarcoidosis is an appearance termed "fairy ring" which refers to circumferentially organized opacities. On this situation a reverse halo sign may be seen.

Other CT abnormalities such as nodules, ground-glass opacities, thickened bronchovascular bundles, and thickened interlobular septae are often seen. 

With prompt and appropriate treatment the alveolar changes are usually reversible 6.

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Article Information

rID: 25982
System: Chest
Tag: cases
Synonyms or Alternate Spellings:
  • Alveolar type sarcoidosis
  • Pseudoalveolar sarcoidosis
  • Pseudoalveolar type sarcoidosis
  • Pseudoalveolar sarcoid
  • Alveolar sarcoid opacities
  • Acinar sarcoidosis

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