Intradural extramedullary ventral thoracic spinal ependymoma: illustrative case.

BACKGROUND: Spinal cord ependymomas are typically intramedullary and rarely present as intradural extramedullary (IDEM) tumors. Here, the authors report a case of a long-segment thoracic IDEM ependymoma that was surgically treated, along with a review of the existing literature on this uncommon presentation. OBSERVATIONS: A 27-year-old female presented with a 1-year history of low back pain. The condition was initially mild and managed conservatively; however, 6 weeks prior to presentation, she developed progressive weakness in both lower limbs. Spinal MRI revealed a large IDEM mass along the ventral aspect of the thoracolumbar spine. The patient underwent laminoplasty (T9-L1 laminae) and gross-total tumor excision. The procedure was well tolerated, and no postoperative complications were observed. Histopathological examination confirmed the diagnosis of a WHO grade 2 ependymoma. At the 2-year follow-up, the patient had normal neurological function, and MRI revealed no evidence of recurrence. LESSONS: IDEM exophytic growth of spinal ependymomas is rare but highly surgically treatable. Although the prognosis is favorable following complete excision, careful attention to the adjacent spinal anatomy is essential to minimize the complications. Further studies are needed to evaluate the role of adjuvant therapy. https://thejns.org/doi/10.3171/CASE26500.