Chronic unilateral airspace opacification (differential)

Chronic unilateral airspace opacification is a subset of the differential diagnoses for airspace opacification. An exhaustive list of all possible causes of chronic unilateral airspace opacities is long, but a useful framework is as follows:

• neoplastic
  • post obstructive
  • lymphoma
  • lymphocytic interstitial pneumonia (LIP)
  • adenocarcinoma

• infective
  • tuberculosis
  • fungal lung infection, especially in immunocompromised patients
  • incompletely treated infection

• inflammatory: usually bilateral, but may be asymmetrical
  • sarcoidosis
  • granulomatosis with polyangiitis
  • eosinophilic pneumonia
  • cryptogenic organizing pneumonia, formerly bronchiolitis obliterans with organizing pneumonia (BOOP)

• other
  • lipoid pneumonia
  • pulmonary hemorrhage: not chronic, but recurrent
  • pulmonary alveolar proteinosis: usually bilateral, by may be asymmetrical
  • radiation pneumonitis