Table 4– Differential diagnosis of delayed post-transplant lung function decline
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.