Background: Solitary plasmacytoma of bone has a predilection for the axial skeleton, most commonly affecting the thoracic spine. We report the case of a patient who presented with acute on chronic back pain and developed severe neurologic deficits within several hours of admission secondary to a pathologic fracture of L1. Methods: The patient underwent an urgent magnetic resonance imaging scan followed by T12 to L2 posterior decompression and T11 to L3 posterior instrumented stabilization. Subsequent histopathologic examination of specimens taken at the time of surgery found this to be secondary to a plasmacytoma affecting the lumbar spine. Results: At follow-up, recovery has been rapid and extensive, with the patient remaining under hematologic review because of the risk for developing multiple myeloma. Conclusions: The unique features of this case relate to the location of the plasmacytoma and the neurologic signs; to our knowledge this is the first reported case in the literature of paraplegia secondary to a lumbar spine plasmacytoma.