A rare case of intradural extramedullary anaplastic ependymoma: a 35-month survival update following resection and adjuvant proton beam radiation therapy. Illustrative case.

backgroundIntradural extramedullary anaplastic ependymomas are rare, aggressive spinal tumors for which optimal management strategies remain unclear. OBSERVATIONS: This case describes ongoing survival at 35 months in a 65-year-old male with an intradural extramedullary anaplastic ependymoma treated with subtotal resection and proton beam therapy. MRI revealed a T2-3 dorsal intradural extramedullary lesion with leptomeningeal spread in the lumbar spine. Subtotal resection was performed due to dense adherence to the cord, with approximately 10% tumor left in situ. Pathological evaluation confirmed MYCN-amplified WHO grade 3 ependymoma. Adjuvant proton beam therapy was initiated within 2 weeks of surgery, consisting of craniospinal irradiation (3600 cGy in 20 fractions) followed by a boost to a total of 5400 cGy in 30 fractions. Postoperative recovery included full return of strength and function. Serial brain and spine MRI studies at 6, 12, 18, and 22 months showed stable spinal dissemination with no intracranial spread. LESSONS: This case supports the role of subtotal resection followed by proton beam therapy as a viable treatment strategy for MYCN-amplified intradural extramedullary anaplastic ependymomas, particularly when gross-total resection is contraindicated. https://thejns.org/doi/10.3171/CASE25804.