Clinical spectrum of idiopathic pneumonia syndrome following haematopoietic stem cell transplantation as categorised by presumed site of primary tissue injury
| Pulmonary parenchyma | Vascular endothelium | Airway epithelium |
| Acute interstitial pneumonitis | Peri-engraftment respiratory distress syndrome | Cryptogenic organising pneumonia |
| Acute respiratory distress syndrome | Diffuse alveolar haemorrhage | |
| Delayed pulmonary toxicity syndrome |