Case of diagnosis and management of primary intradural extramedullary Ewing's sarcoma.

Background: Primary intradural extramedullary Ewing's sarcoma (IEES) is an exceptionally rare, aggressive central nervous system malignancy. It poses distinct diagnostic and therapeutic challenges compared with osseous Ewing's sarcoma. Case Description: A 45-year-old female presented with 6 weeks of progressive bilateral lower limb pain. The magnetic resonance imaging revealed a T1-hypointense, T2-hyperintense intradural extramedullary mass from L3-S1 (~2 × 0.5 × 1 cm). Through an L3-L5 laminectomy, the tumor was fully excised under neurophysiological monitoring. Although the tumor extended radiologically to the S1 level, it was accessed through the L3 -L5 laminectomy after durotomy, which provided adequate exposure for dissection and complete excision of the extending intradural lesion. The histopathology demonstrated sheets of small round cells, while the immunohistochemistry showed CD99 and FLI-1 positivity. The patient received adjuvant vincristine, doxorubicin, cyclophosphamide (VAC)/ifosfamide/etoposide chemotherapy, and intensity-modulated radiation therapy. At 12-month follow-up, there was no evidence of recurrence. Conclusion: IEES demands a high index of clinical suspicion and aggressive multimodal treatment. For this patient, surgical decompression and chemotherapy have left the patient disease-free 1 year postoperatively. However, the patient will continue to require careful surveillance for recurrent disease. Further studies are warranted to develop standardized management protocols.