Occult myopathy of the vastus intermedius muscles detected by magnetic resonance imaging in subclinical dermatomyositis: report of two cases.

[focal myositis]

Abstract The thigh muscles of two patients with dermatomyositis (DM ) without muscle weakness or conspicuous creatine kinase elevations were studied by magnetic resonance imaging (MRI ). Myositis limited to the vastus intermedius muscles (VIM ) was detected in both patients , and in one , the diagnosis was confirmed by the findings of a biopsy specimen . Focal myositis of the VIM in early -stage DM , which otherwise would remain hidden by the relatively small muscle size and deep location , can be detected by MRI .