Pulmonary veno-occlusive disease: pathogenesis, risk factors, clinical features and diagnostic algorithm - state of the art.

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary haemangiomatosis (PCH) are rare disorders, with the estimated prevalence of less than 1 case per million inhabitants. The vascular pathology in PVOD/PCH involves pre-septal and septal veins, alveolar capillaries and small pulmonary arteries. According to the ERS/ESC classification of pulmonary hypertension (PH) from 2015, PVOD/PCH have been included in the subgroup 1' of pulmonary arterial hypertension (PAH). Recent data indicate, however, the possibility of PVOD/PCH pathology in the patients diagnosed in the group 1. The problem may concern PAH associated with scleroderma, drug- induced PAH, PAH due to HIV infection and up to 10% of patients with idiopathic PAH (IPAH). Recently, bi-allelic EIF2AK4 mutations were found in the cases with heritable form of PVOD/PCH and in about 9% of sporadic cases. Moreover, an association between occupational exposure to organic solvents and PVOD/PCH was proved. The present review is an attempt to summarise the current data on pathogenesis, risk factors, clinical features and diagnostic algorithm for PVOD/PCH.