Chronic airspace opacities (bilateral)
The differential for airspace opacities is very extensive, and needs to be interpreted in context of chronicity (previous imaging) and clinical context. An exhaustive list of all possible causes of chronic bilateral airspace opacities is long, but a useful framework is as follows:
- Inflammatory
- sarcoidosis
- Wegener's granulomatosis
- eosinophilic pneumonia
- cryptogenic organizing pneumonia, formerly bronchiolitis obliterans organizing pneumonia (BOOP)
- polyarteritis nodosa (PAN)
- Churg-Strauss syndrome
- Infective
- tuberculosis
- fungal (especially in immunocompromised)
- incompletely treated infection
- Neoplastic / Lymphoproliferative
- lymphoma
- lymphoid interstitial pneumonia (LIP)
- bronchoalveolar carcinoma (BAC)
- post obstructive
- Other
- lipoid pneumonia
- haemorrhage (not chronic, but recurrent)
- alveolar proteinosis
