Unexpected myxopapillary ependymoma within a filum terminale tethering the spinal cord.

We present a 9-month-old neurologically normal infant with cutaneous markers for a closed neural tube defect consisting of two sacral dimples and associated tuft of hair. Magnetic resonance imaging showed that her spinal cord was tethered at S2 and associated with a large syrinx. A myelotomy was performed to address the hydrosyringomyelia and the filum terminale resected to untether the spinal cord. Histopathologic examination of the filum terminale specimen revealed the presence of an unexpected myxopapillary ependymoma. The association of a myxopapillary ependymoma with a closed neural tube defect appears to be coincidental. This patient may have presented at some future date with a clinically symptomatic myxopapillary ependymoma. The presence of microscopic myxopapillary ependymoma cells in this infant's filum supports the concept that these tumors arise from embryonic rests of ependymal cells.