| 1) Bronchiolitis obliterans syndrome (BOS) |
| 2) Non-BOS alloinflammatory processes |
| a) Acute cellular rejection |
| b) Lymphocytic bronchiolitis |
| c) Antibody-mediated rejection (humoral, vascular) |
| 3) Restrictive allograft syndrome |
| 4) Inflammatory complications of the lung allograft |
| a) Pleuro-parenchymal inflammation |
| i) Bronchiolitis obliterans organising pneumonia (BOOP) |
| ii) Fibrinoid and organising pneumonia (FOP) |
| b) Chronic inflammation of airways |
| i) Large airways (bronchiectasis#, bronchomalacia) |
| ii) Bronchioles (follicular or exudative bronchiolitis) |
| c) Chronic pleural inflammation |
| d) Chronic vascular rejection |
| 5) Infection |
| 6) Surgical removal of lung tissue |
| 7) Mechanical abnormality |
| a) Airway dysfunction |
| i) Anastomotic stricture/stenosis |
| ii) Bronchomalacia (allograft, native airway in SLT) |
| b) Allograft compression |
| i) Weight gain |
| ii) Abdominal distention |
| iii) Hyperinflation of native lung in SLT for emphysema |
| iv) Pleural complications |
| 1. Pneumothorax |
| 2. Pleural effusion |
| 3. Pleural fibrosis |
| 4. Bronchopleural fistula |
| c) Impaired graft inflation |
| i) Pain (vertebral fracture, fracture of ribs and/or sternum) |
| ii) Ventilatory compromise |
| 1. Diaphragmatic dysfunction or paralysis |
| 2. Chest wall myopathy |
| iii) Other (cerebrovascular accident, Parkinson’s disease, etc.) |
| d) Drug reaction (e.g. sirolimus, everolimus and amiodarone) |
| e) Pulmonary oedema |
| f) Malignancy (PTLD or other) |
| 8) Vascular obstruction |
| a) Allograft anastomotic large vessel strictures |
| b) Thromboembolic disease |
| c) Tumour emboli |
| 9) Allograft parenchymal abnormalities |
| a) Transplant indication disease recurrence |
| i) Interstitial diseases (e.g. sarcoidosis, PLCH and LAM) |
| ii) Other (e.g. veno-occlusive disease, connective tissue disorders) |
| b) Diffuse alveolar damage |
| c) Organising pneumonia |
| 10) Ageing |
SLT: single lung transplant; PTLD: post-transplant lymphproliferative disease; PLCH: pulmonary Langerhans’ cell histiocytosis; LAM: lymphangioleiomyomatosis. #: Bronchiectasis may be a manifestation of obliterative bronchiolitis/BOS.