Multiple myeloma mimicking bone metastasis from breast cancer: report of a case.

A 72-year-old woman with a history of early breast cancer suffered a fracture of the eighth thoracic vertebra resulting in paraplegia. Magnetic resonance imaging (MRI) showed spinal cord compression by a tumor between the ninth and tenth thoracic vertebrae. Local radiotherapy was begun under the diagnosis of metastatic breast cancer, but bone marrow aspiration and biopsy subsequently revealed plasma-cell proliferation rather than adenocarcinoma. This case report serves to demonstrate that clinicians should consider multiple myeloma as a cause of lytic bone lesions without extraskeletal metastases even in patients with a history of breast cancer.