Metastases of spinal myxopapillary ependymoma: unique characteristics and clinical management.

OBJECTIVE Myxopapillary ependymoma is a benign WHO Grade I tumor most commonly located in the conus-cauda equina region of the spine. Although this tumor is defined by an overall excellent survival, dissemination throughout the whole neuraxis occurs frequently. The current study evaluated the clinical characteristics and significance of myxopapillary ependymoma metastases. METHODS Patients who underwent surgery from 2005 to 2015 for treatment of spinal myxopapillary ependymoma were included in the study. Charts were reviewed for primary tumor symptoms and initial treatment, local recurrence, response to salvage therapy, and presence and behavior of distant metastases. RESULTS Nineteen patients with spinal myxopapillary ependymoma were included in the study (52.6% female). The median age at first diagnosis was 32 years old (range 9-58 years old), and 26.3% were ≤ 18 years old. The median follow-up of all included patients was 48 months (range 6-456 months). Of the primary tumors, 84.2% were located in the lower thoracic or upper lumbar spine, spanning 1-3 levels in 94.7%. All patients underwent surgery for initial treatment: in 78.9% a gross-total resection (GTR) was achieved, with adjuvant radiation therapy (RT) in 20%. Of the 21.2% who underwent a subtotal resection (STR), 75% underwent postoperative RT. Tumor progression was noted in 26.3% of patients after a median 36-month follow-up (range 12-240 months). In 57.9% of patients, distant metastases were found, of which 36.4% were present at initial diagnosis. Further metastases occurred within a median of 20 months (range 2-360 months). Following a diagnosis of metastatic tumor, 72.7% did not show progression and no symptoms were observed during a median follow-up of 36 months (range 6-216 months). Metastases occurred in all parts of the neuroaxis, but were principally localized in the thoracic and sacral spine in 38.9% and 33.3%, respectively; the brain was involved in 11.1%. In 54.5%, more than 1 level was affected. Overall survival was 100% with an excellent clinical and neurological outcome in 78.9% of cases. CONCLUSIONS Metastatic dissemination within the CNS can be observed in many patients with myxopapillary ependymoma. GTR of the primary tumor should be the primary treatment goal, and additional RT is recommended after STR. For distant metastases of myxopapillary ependymoma without clinical manifestation, close clinical and MRI follow-up represents a sufficient strategy because most of the metastases remain asymptomatic and do not show progression over time. Additional resection or irradiation as salvage therapy would be recommended if metastases become symptomatic.