Spinal intradural lesion as manifestation of multiple myeloma: Illustrative case and systematic review of literature.

Background: Multiple myeloma (MM) typically affects the bone marrow. When it spreads to the central nervous system, it usually presents as intracranial metastasis or extradural spinal lesions. Intradural spinal cord metastases are exceedingly rare. Case Description: A 53-year-old male with immunoglobulin A kappa MM presented with a contrast-enhancing lesion at the T3-4 level, consisting of an intradural lesion and an extradural lesion extending through the foramen. The lesion's characteristics suggested a schwannoma, but MM involvement was suspected given the patient's history. Surgical resection and spinal stabilization were performed, and pathological examination confirmed a plasma cell neoplasm. A systematic review of the literature identified 10 cases of intradural spinal lesions associated with MM or solitary plasmacytoma. Most lesions were intradural extramedullary, located primarily in the thoracic spine. Management often included surgery, chemotherapy, and radiotherapy, but the prognosis remained poor, especially with leptomeningeal spread. Conclusion: This case highlights the diagnostic and therapeutic challenges of intradural spinal MM involvement. While surgery can provide symptomatic relief and confirm the diagnosis, the risk of leptomeningeal dissemination requires close monitoring. A multidisciplinary approach is essential for managing these rare and complex cases, and further studies are needed to refine treatment strategies and improve patient outcomes.