[Symptomatic bilateral soft tissue tumor of the breast wall].

A 54-year-old woman presented with progressive swelling of the right scapula as well as motion-dependent pain. The medical history revealed a polyglandular autoimmune syndrome and lumbar disc degeneration. The magnetic resonance imaging (MRI) scan showed a bilateral well-defined muscle isointense space-occupying lesion situated between the scapula, rib cage and thoracic muscles with homogeneous contrast enhancement. The constellation is indicative of a elastofibroma dorsi, a rare mesenchymal tumor often appearing bilaterally.