Intradural plasmacytoma originating from the filum terminale in the setting of multiple myeloma: illustrative case

BACKGROUND: Multiple myeloma (MM) has the propensity to spread to vertebral bodies; however, extramedullary plasmacytomas involving the central nervous system are extremely rare. OBSERVATIONS: The authors report the first intradural extramedullary plasmacytoma in the lumbar region of the spine in a patient with preexisting MM. They present a 50-year-old female with severe back and radicular pain and progressive neurological deficit. LESSONS: MM is typically treated with chemotherapy and radiation therapy. However, in this unique case, resection proved to be a key part of treatment.