| Pre-capillary | Typical vascular remodelling of pulmonary hypertension with hypertrophy of the media of the pulmonary arteries, resulting in reduced arborisation of the pulmonary arterial tree |
| Parenchymal | Accumulation of intraparenchymal siderophages |
| Septal thickening |
| Mild interstitial fibrosis |
| Pleural plaques owing to organisation of fibrinous exudates |
| Lymphatic | Enlarged hilar lymph nodes |
| Lymphangiectasis |
| Pleural effusion |
| Post-capillary | “Arterialisation” of the pulmonary veins with intimal fibrosis and medial thickening |
| Venous varices mimicking arteriovenous malformations |
| Bronchovascular | Remodelling of the bronchial arteries and bronchial veins with bronchovascular ectasis |
| Endobronchial | Friable endobronchial mucosa predisposed for haemoptysis and recurrent airway infection |