Cervical intradural extramedullary relapse of multiple myeloma: Case report and review of the literature

Multiple myeloma (MM) frequently involves the spine through vertebral lesions with epidural extension causing spinal cord compression. Intradural extramedullary (IDEM) spinal involvement is exceedingly rare and may mimic common IDEM tumors such as schwannoma or meningioma on MRI. Case presentation: A 66-year-old man with MM in complete hematologic remission presented with worsening right cervicobrachial neuralgia progressing to cervical myelopathy with Brown–Séquard syndrome. Cervical MRI revealed a solitary contrast-enhancing IDEM mass at C3 with right foraminal extension, initially suggestive of schwannoma. The patient underwent surgical decompression and gross-total resection. Histopathology and immunohistochemistry confirmed a plasma cell neoplasm consistent with MM relapse (plasmacytoma). The patient was referred to the hematology department for multidisciplinary management. Conclusion: IDEM spinal involvement in MM is exceptional. Surgical resection is often required for diagnosis and urgent decompression, followed by adjuvant oncologic treatment.