Intraspinal extradural myxopapillary ependymoma of the sacrum arising from the filum terminale externa

Extradural ependymomas of the sacrococcygeal region are very rare, with most arising from the soft tissues of the presacral area or from the regions dorsal to the sacrum. In even rarer circumstances, the rumor may arise within the sacral canal, likely as a result of ependymal cells of the extradural filum terminale. Because of bone erosion caused by extension of the tumor into the pelvis or dorsal to the sacrum, a truly intraspinal extradural ependymoma in this region has until now never been clearly demonstrated. The authors present a patient with a myxopapillary ependymoma arising from the filum terminale externa in which there was no involvement of the intradural filum or extension outside the sacral canal. A review of the literature is presented, with emphasis on the pathogenesis and clinical management of these rare tumors.