We describe a 73-year-old forest owner with widespread erythema, myalgia, and proximal muscle weakness. The clinical signs and the results of electromyography, magnetic resonance imaging, and a muscle biopsy were consistent with dermatomyositis. However, serology was positive for Borreliu burgdorferi. More importantly, B burgdorferi DNA was detected in skin by polymerase chain reaction techniques, and spirochetelike organisms were detected in the muscle by silver staining. Lyme disease with muscle involvement can mimic or trigger dermatomyositis and should be considered in the differential diagnosis of dermatomyositis.
Lyme disease is a multisystem organ disease caused by Borreliu burgdorferi. It primarily affects the skin, joints, nervous system, and heart (I). Although this is uncommon, B burgdorferi has been shown to infiltrate into the muscles, causing a special form of myositis, which is usually localized and is often associated with neurologic symptoms (2-1 1).
We report the case of a patient with typical features of dermatomyositis, including recurrent rashes and proximal muscle weakness. Examination of skin and muscle biopsy samples, however, showed invasion by B burgdorferi, spirochete-like organisms, and mononuclear cell infiltrates. To our knowledge, this is the first report of a patient with definite Lyme disease that is clinically almost indistinguishable from dermatomyositis.