Case Report: Primary sporadic intramedullary malignant peripheral nerve sheath tumor with intracranial extension and a subpial nodule suggestive of early dissemination

Background: Intramedullary malignant peripheral nerve sheath tumors (MPNSTs) are exceptionally rare, particularly in sporadic cases without neurofibromatosis type 1 (NF-1) or prior radiotherapy. Case presentation: A 22-year-old male presented with progressive left-sided weakness, gait imbalance, and sensory disturbance. MRI revealed an intramedullary C2 mass with intracranial extension and a small dorsal subpial enhancing nodule at C5, raising concern for early neuraxial dissemination. Gross total resection confirmed MPNST. Recurrence developed 18 months later with left cerebellar extension and immunophenotypic dedifferentiation. The patient subsequently experienced rapid clinical deterioration and died 14 months after recurrence. Conclusion: This case highlights the highly aggressive biological behavior of sporadic intramedullary MPNST, including rapid progression despite gross total resection. Early recognition of atypical imaging features suggestive of dissemination and consideration of multimodal treatment strategies may be important for optimizing surveillance and management.