Myxopapillary ependymoma with a knotted filum terminale: illustrative case.

Background: A 32-year-old male with no previous significant medical history presented to the authors' clinic with a 7-week history of severe low back pain. The patient was evaluated with MRI, which revealed a large intradural spherical enhancing mass behind the L1 vertebral body. He was subsequently treated with a left L1-2 hemilaminectomy and excision of the tumor.

Observations: Although the excision was uncomplicated, it was noted that the lesion was attached to a knotted filum terminale. Pathological analysis determined that this tumor was a WHO grade 1 myxopapillary ependymoma (MPE). The patient's postoperative course was unremarkable, and he was discharged home from the hospital the same day. He had complete resolution of his presenting symptoms at his first routine postoperative visit 2 weeks after surgery. Postoperative lumbar MRI at 2 months demonstrated no residual tumor.

Lessons: This is the first illustrative case of an MPE attached to a knotted filum terminale reported in the literature. https://thejns.org/doi/10.3171/CASE2444.