Pulmonary veno-occlusive disease: the bête noire of pulmonary hypertension in connective tissue diseases?

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension that may develop in patients with connective tissue diseases (CTD). Most cases have been reported in patients with systemic sclerosis, though associations with systemic lupus erythematosis and mixed connective tissue disease have also been described. PVOD is characterised by progressive obstruction of small pulmonary veins and venules that leads to increased pulmonary vascular resistance, right heart failure and premature death. Distinguishing PVOD from pulmonary arterial hypertension (PAH) is often difficult, though use of a diagnostic algorithm may improve diagnostic accuracy and preclude recourse to lung biopsy. The finding of normal left-heart filling pressures in the context of radiological studies suggestive of pulmonary oedema is an important diagnostic clue, particularly if this clinical scenario coincides with the introduction of vasodilator therapy. There are no approved treatments for the disorder, though cautious use of PAH specific therapy may improve short-term outcomes in selected idiopathic PVOD cases. This review summarises the epidemiologic, clinico-pathologic and imaging characteristics of PVOD in the setting of CTD and discusses potential management approaches.