Correlation between muscular edema on magnetic resonance imaging versus major histocompatibility complex type Ii overexpression on muscle biopsy at diagnosis on juvenile dermatomyositis patients

Introduction Juvenile Dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in childhood. Magnetic resonance imaging (MRI) is a non invasive tool to assess muscular edema. Its ability to distinguish between active JDM patients and inactive and healthy children is well described in the literature. However muscle biopsy still remains the gold standard in JDM diagnosis. Major Histocompatibility Complex (MHC) type I is overexpressed on sarcolemma of inflammatory myopathies and it could be detectable before inflammatory infiltrate appears on conventional tecniques and remains there in spite of treatment.