Juvenile dermatomyositis (JDM) is the early-onset form of dermatomyositis (DM), a systemic, autoimmune inflammatory muscle disorder, characterized by proximal muscle weakness, evocative skin lesion, and systemic manifestations. The disease is juvenile dermatomyositis (MONDO_0008054). Also known as: childhood dermatomyositis, inflammation of myoseptum, juvenile DM, myoseptum inflammation, myoseptumitis.