Airway obstruction | Foreign body |
| Tumour |
| Broncholithiasis |
| External compression of bronchus |
Cystic fibrosis | |
Reduced host immunity | Congenital and acquired hypogammaglobulinaemia |
| Malignancy |
| HIV infection |
Post-infection (tuberculosis, pertussis, measles, etc.) | |
Allergic bronchopulmonary mycoses | |
Chronic Mycobacterium avium complex infection | |
Aspiration or toxic inhalation | |
Rheumatoid arthritis | |
Systemic lupus erythematosus | |
Relapsing polychondritis | |
Sjögren syndrome | |
Inflammatory bowel disease | |
Other congenital disorders | α1-Antitrypsin deficiency |
| Primary ciliary dyskinesia |
| Tracheobronchomegaly (Mounier-Kuhn syndrome) |
| Bronchial cartilage deficiency (Williams–Campbell syndrome) |
| Young’s syndrome (azoospermia and chronic sinopulmonary infections) |
| Bronchopulmonary sequestration |
| Marfan syndrome |
Yellow nail syndrome (lymphoedema, pleural effusions, hypertrophic nails) | |