Saper VE, Chen G, Deutsch GH, et al. - In a multicentre retrospective study, 61 cases were examined using physician-reported clinical data and centralized analyses of radiological, pathological and genetic data in order to examine the features and risk factors of a novel parenchymal lung disease (LD), increasingly discovered in systemic juvenile idiopathic arthritis (sJIA). It was discovered that in sJIA, a rare, life-threatening lung disease is described by a constellation of unusual clinical features. The pathology, a pulmonary alveolar proteinosis and/or endogenous lipoid pneumonia variant, implies macrophage dysfunction. In a small subset of treated individuals, inhibitor exposure may develop LD, irrespective of sJIA severity. Treatment/prevention approaches are required, nonetheless.