Radiation-induced meningeal osteosarcoma of tentorium cerebelli with intradural spinal metastases

BACKGROUND: Primary meningeal osteosarcomas and radiation-induced extraosseous tumors are extremely rare. We encountered a patient with a radiation-induced meningeal osteosarcoma with metastatic spread. CASE DESCRIPTION: A 54-year-old man presented with a 2-week history of nausea, vomiting, and ataxia. CT and MRI studies revealed an extra-axial, dural-based mass in the posterior fossa arising from the tentorium cerebelli. The patient underwent complete resection of the tumor with adjuvant chemotherapy. Histopathologic analysis revealed chondroblastic osteosarcoma. Tumor recurrence was observed 9 months after initial diagnosis, and adjuvant radiation therapy was administered. The intracranial disease stabilized; however, multiple cervico-thoracic spinal metastases were discovered 15 months after initial diagnosis. The patient expired 16 months after initial diagnosis. CONCLUSION: Meningeal osteosarcomas are rare lesions that can metastasize and should be considered in the differential diagnosis for dural-based lesions, especially in the case of previous radiation therapy.