脊椎および脳神経外科ジャーナル

Extramedullary Non-Myxopapillary Ependymoma of the Cauda Equina: A Case Report and Review of the Literature

Yoshiomi Kobayashi, Akio Iwanami, Osahiko Tsuji, Morito Takano, Tokuhiro Kimura, Yoshiaki Toyama and Masaya Nakamura

Extramedullary Non-Myxopapillary Ependymoma of the Cauda Equina: A Case Report and Review of the Literature

Ependymomas have been described as the most common primary spinal cord tumor, most frequently located near the conus medullaris. These tumors are almost intramedullary in location, with only rare case reports of extramedullary tumors. Furthermore, the vast majority of extramedullary ependymomas in the cauda equina are classified as myxopapillary. To our knowledge, only 17 cases of extramedullary ependymomas have been reported previously in the literature. Furthermore, only three cases of non-myxopapillary ependymomas, including our case, have been reported. We report here a case of extramedullary non-myxopapillary ependymoma of the cauda equina.

A 41-year-old male patient with a 1-year history of low back pain and numbness in the right leg was referred to our hospital after a magnetic resonance imaging (MRI) study showed an intradural and extramedullary tumor at the L1 level. The differential diagnosis was schwannoma, meningioma, epidermoid, paraganglioma, or myxopapillary ependymoma of the cauda equina.

The tumor was finally diagnosed as a non-myxopapillary ependymoma with a MIB-1 proliferation index of 5%, which is higher than that of cellular or myxopapillary ependymomas. A gross total resection was achieved and adjuvant fractionated radiotherapy was not thought to be indicated. A long-term follow-up will be performed because of the higher MIB-1 index observed.