Juvenile Dermatomyositis: Key Roles of Muscle Magnetic Resonance Imaging and Early Aggressive Treatment.

Juvenile dermatomyositis is a rare systemic connective tissue disease with onset during childhood. It presents clinically with proximal muscle weakness and characteristic skin involvement. Diagnosis is based on the Bohan and Peter criteria, though many authors are now substituting biopsy with muscle magnetic resonance imaging (MRI) for both diagnosis and follow-up. Without intensive early treatment, complications such as calcinosis cutis and lipodystrophy can develop in the chronic phases of the disease. Early recognition is therefore key to management. We present a series of 5 patients who were diagnosed with Juvenile dermatomyositis on muscle MRI without undergoing muscle biopsy and who received early treatment. We draw attention to the usefulness of muscle MRI for the diagnosis of muscle involvement and to the importance of early initiation of intensive treatment to prevent complications.