Categorisation and features of diffuse cystic lung diseases5 7 8
| Clinical features | Characteristic CT findings | |
|---|---|---|
| Cystic lesions primarily of the lung | ||
| Light-chain derived (AL) pulmonary amyloidosis | Associated with blood dyscrasias and lymphoproliferative disorders | Cysts of diverse sizes and shapes; seen more commonly with septal thickening, irregular nodularity and tracheobronchial lesions |
| LAM | Associated with pneumothorax, chylous effusions/ascites, renal angiomyolipomas and/or tuberous sclerosis complex | Round, uniform cysts intermittently dispersed throughout normal lung parenchyma |
| Langerhans cell histiocytosis | Almost exclusively in smokers | Associated with centrilobular nodules; classically spares costophrenic angle |
| Sporadic cystic lung disease | Associated with small airways disease, hypothesised to be a consequence of chronic small airway injury | Cysts of diverse sizes and shapes; associated with evidence of bronchiolitis |
| Follicular bronchiolitis | Thought to be on similar pathological spectrums, follicular bronchiolitis and LIP are almost clinically indistinguishable; can be associated with connective tissue diseases | Cysts of diverse sizes and shapes; associated peribronchial distribution with parenchymal nodularity and tree-in-bud like appearances |
| LIP | Cysts of diverse sizes and shapes; associated with perivascular distribution and ground-glass opacities | |
| Cystic lesions secondary to other diseases | ||
| Serum amyloid A (AA) pulmonary amyloidosis | Generally well tolerated and associated with diseases of chronic inflammation | Similar to primary pulmonary amyloidosis |
| Cystic metastasis | Reported in a diversity of cancers including colon cancer, bladder cancer, sarcoma and stromal tumours | Cysts of diverse sizes and shapes; cysts can be filled with either fluid or air |
| HIV | Most profound in patients who smoke; unclear relation to infections | Large, irregularly shaped cysts with emphysematous appearances |
| Cystic lesions with genetic origins | ||
| Tuberous sclerosis complex | Linked to mutations in the TSC1 or TSC2 gene | Radiographically similar to LAM |
| Birt-Hogg-Dubé syndrome | Linked to mutations in the FLCN gene; familial history of pneumothorax | Irregularly sized and shaped cysts; typically subpleural most predominant in lower lobes |
| Cystic fibrosis | Linked to mutations to the CFTR gene; associated with recurrent pulmonary infections, pancreatic insufficiency and nutritional deficiencies | Cysts of varying sizes favouring central, apical presentations associated with bronchiectasis |
HIV, human immunodeficiency virus; LAM, lymphangioleiomyomatosis; LIP, lymphocytic interstitial pneumonia.