A Case of Polymyositis Presenting as Bent Spine Syndrome

Polymyositis (PM) is a subset of idiopathic inflammatory myopathies. The muscles involved with PM are typically proximal and distal limb muscles, but paraspinal muscles are rarely affected. The primary PM clinical symptom is gradual proximal muscle weakness but unusually abnormal trunk posture. Bent spine syndrome (BSS), also referred to camptocormia, is defined as an abnormal flexion of the trunk, appearing in standing position. An idiopathic axial myopathy is the most common cause of primary BSS. A few cases of inflammatory myopathy, a secondary BSS, have been reported. We describe a 59-year–old polymyositis patient with normal finding on an magnetic resonance imaging femur scan who presented with BSS only, myopathic findings on electromyography and elevation of muscle enzymes. (J Rheum Dis 2016;23:261-265)