Schulert GS, Yasin S, Carey B, et al. - Experts explained the clinical features, risk factors, and histopathologic and immunologic peculiarities of the novel inflammatory lung disease (LD) related to systemic juvenile idiopathic arthritis (JIA) (designated SJIA-LD). Clinical data assembled since 2010 were summarized from the medical records of patients with systemic JIA from the Cincinnati Children's Hospital Medical Center. Eighteen individuals with SJIA-LD were recognized. Pulmonary disease was frequently identified in children with systemic JIA, especially in relation to macrophage activation syndrome. This entity had different clinical and immunologic characteristics and designated an uncharacterized inflammatory LD.