Neely J, et al. - In this cross-sectional study, researchers explored the connection between ultraviolet (UV) radiation and severe disease outcomes in juvenile dermatomyositis (DM). The sample consisted of patients with juvenile DM enlisted in the US multicenter Childhood Arthritis and Rheumatology Research Alliance Legacy Registry from 2010 to 2015. No association was found between the mean UVI and calcinosis in a multivariable model. African American race was related to a 3-fold greater odds of calcinosis. However, a significant statistical interaction was noted between race and mean UVI. Higher mean UVI was linked to reduced odds of using biologics or nonmethotrexate disease-modifying antirheumatic drugs and skin ulceration. In a large cohort of patients with juvenile DM, a novel association was found between UV radiation, calcinosis, and race. This research fosters awareness of the role of UV radiation in juvenile DM's clinical course and highlights the complex interplay of genes and environment in clinical phenotypes and calcinosis development in children with juvenile DM.