[Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis]

The new classification of pulmonary hypertension proposed in the joint European Society of Cardiology (ESC) and European Respiratory Society (ERS) guidelines, combines pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) from separate categories into a single subcategory within pulmonary arterial hypertension (PAH) because of specific similarities in their diagnosis, prognosis, and management. These diseases are characterized histologically by their predominant involvement of small pulmonary veins (PVOD) and capillaries (PCH). Their precise prevalence is not known, but they are thought to account for 5 to 10% of the forms of PAH initially considered idiopathic. They cannot be distinguished from idiopathic PAH by their clinical or hemodynamic presentation. Only pathology examination can confirm the diagnosis, but lung biopsies are high-risk procedures and not recommended. A less invasive approach combining chest CT (centrilobular ground-glass opacities, septal lines, and mediastinal adenopathy), blood gases (resting hypoxemia), lung function tests [collapse in carbon monoxide diffusion (DLCO)] and bronchoalveolar lavage (occult intra-alveolar hemorrhage) makes it possible to screen the patients at risk of PVOD or HCP and thus avoid a lung biopsy. These patients have a poor prognosis and are at risk of developing severe pulmonary edema after the initiation of specific treatment for PAH. In view of their limited response to specific treatment and poor prognosis, pulmonary transplantation remains the treatment of choice for PVOD and HCP. In patients with the most severe disease, the prudent use of continuous intravenous epoprostenol, can serve as bridge-therapy while awaiting a lung transplant.