Pulmonary arterial hypertension in systemic sclerosis: a distinctive endotheliopathy?

We read with great interest the recent article by OVERBEEK et al. [1] on the histological differences in pulmonary vessels from patients with pulmonary arterial hypertension (PAH) related to systemic sclerosis (SSc) versus idiopathic PAH (IPAH). The study demonstrates that pulmonary pathological features in patients suffering from limited cutaneous SSc (lcSSc) differ from the ones seen in IPAH, in relation to the occurrence of small vessel intimal fibrosis, the presence of pulmonary venoocclusive disease-like lesions, and the absence of plexiform lesions in the former group. OVERBEEK et al. [1] correctly suggest that their findings point to the presence of a distinct vasculopathy in the SSc cohort that may contribute to the lower transfer factor of the lung for carbon monoxide (TL,CO) and, more importantly, to the worse prognosis in PAH-SSc versus IPAH. The authors further propose that different pathogenetic mechanisms should underlie PAH development in the two groups, and that pulmonary endothelial function should be a determinant of such dissimilar mechanisms [1].