The juvenile idiopathic inflammatory myopathies (JIIM) are systemic autoimmune diseases
characterized by skeletal muscle weakness, characteristic rashes, and other systemic
features. In follow-up to our study defining the major clinical subgroup phenotypes of JIIM,
we compared demographics, clinical features, laboratory measures, and outcomes among
myositis-specific autoantibody (MSA) subgroups, as well as with published data on adult
idiopathic inflammatory myopathy patients enrolled in a separate natural history study. In the …