Teaching Case

A 32-year-old male patient starting with non-irradiated low-back pain, which does not go away with usual analgesic therapy. A week later he begins to notice a loss of strength in right lower limb, which has worsened over time. He continues with low-back pain which not irradiated.

Dorsal and lumbar MR examination showed two differents lesions, one in thoracic cord and the second one in the cauda equina.
The upper lesion is a intradural extramedullary thoracic lesion, lobulated and well-circumscribed, isointense to cord on T1-weighted images. On T2w-images the lesions appeared hyperintense. Homogeneous enhancement is shown on contrast-enhanced T1-weighted image. The lesion occupies the spinal canal and displaces the thoracic medulla anteriorly and laterally to the left.
Lumbar MR images show the second lesion in filum terminale at L2-L3 level. Lesion shows marked homogeneous enhancement, but no expansion to the spinal canal, nor has caused scalloping of the vertebral bodies. T1-weighted sagittal image demonstrates an inferior component of the tumour that is hyperintense, probably in relation to a mixoid or haemorrhage intratumoral component, these findings are often present in myxopapillary ependymoma.

Ependymomas are slowly growing CNS tumours that arise from ependymal cells of cerebral ventricles and cells lining the central canal of the spinal cord [1]. Spinal ependymomas usually present as intramedullary lesions, they are the most common intramedullary tumours in adults. They account for 60% of all intramedullary tumours.
Intradural extramedullary (IDEM) ependymomas subtype are extremely rare, they may arise from heterotopic ependymal cell rests were left in the IDEM space when the neural tube closed. And furthermore, multiple IDEM ependymomas are even rarer, only several cases have been reported [2].
Intramedullary ependymomas mainly located at the cervical spinal cord and the conus medullaris as exophytic tumours in contrast most spinal IDEM ependymomas that affect the thoracic spine [3, 4]. IDEM ependymomas are extremely rare and predominate in women in the 5th decade of life. Pain is the most frequent initial symptom [5]. Intradural extramedullary presentation is rarely described except for those located at the terminal filum or conus medullaris [6].
Myxopapillary ependymoma is a histological variant that can be distinguished from the ordinary type of ependymoma because of its generally better prognosis [6]. Myxopapillary ependymomas are an ependymoma variant thought to arise from the ependymal glia of the filum terminale or conus medullaris. They account for approximately 50% of adult spinal ependymomas [7]. They should be considered in the differential diagnosis of multiple IDEM tumours [1].
Histologically, ependymal rosettes and perivascular pseudorosettes that characteristically mark ependymomas are absent or are not well-formed in the myxopapillary subtype, although mucoid stroma, is a distinctive feature of myxopapallyillary ependymoma [6].
On T1-weighted images, myxopapillary ependymomas are typically isointense, but these tumours have a prominent myxoid mucinous component that occasionally results in T1 hyperintensity. They are hyperintense on T2-weighted imaging, although low-signal may be seen at the tumour margin because of haemorrhage. Homogeneous enhancement typically occurs, although it depends on the presence of haemorrhage [7].
Myxopapillary ependymoma is histopathologically benign, grade I in the World Health Organization (WHO) classification, however, malignant transformation can occur, leading to recurrence or intradural dissemination. Outcome depends on the extent of surgical resection, the prognosis is excellent if the resection is complete [6]. There is a risk of local recurrence if the resection is incomplete, and radiotherapy is used in these cases [7].