Juvenile dermatomyositis
Children with inflammatory myopathies have clinical and laboratory features, as well as risk factors and outcomes that overlap with their adult counterparts. However, a number of important differences exist between pediatric and adult disease. Juvenile dermatomyositis (JDM), the most common of this group of illnesses in children, has an incidence of approximately 3.2 cases/million children/year. JDM has a gender ratio of 2 girls:1 boy. JDM has a mean age of 6.7 years at disease onset. The duration of active disease before the time of diagnosis alters the patients' features at presentation as well as their clinical outcomes. Environmental and genetic factors affect the child's susceptibility to these conditions and also alter the inflammatory response, adding heterogeneity to disease pathophysiology. © 2010 Springer-Verlag London.
