RESUMEN
Extramedullary plasmacytoma (EMP) is a common plasma cell tumor often involving the upper aerodigestive tract. Although extremely rare, mediastinal involvement is possible. An 81-year-old man was presented to our emergency department with chest and back pain with weakness in both legs. Chest X-ray showed a large mass in the upper right mediastinum; subsequently, computed tomography and magnetic resonance imaging evaluated the mass. He was diagnosed with mediastinal EMP, which progressed to spinal cord compression. The patient was treated with radiotherapy and chemotherapy. Spinal cord compression, due to metastatic tumor, is an emergency clinical situation that requires prompt diagnosis and treatment. Emergency medicine physicians should be aware of the clinical presentation and complications associated with EMP.