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Myxopapillary Ependymoma


KEY FACTS

Terminology

  • Slow-growing glioma arising from ependymal cells of conus, filum terminale, cauda equina

Imaging

  • Usually spans 2-4 vertebral segments

    • May fill entire lumbosacral thecal sac

  • Ovoid, lobular, sausage-shaped

  • CT/radiographs

    • ± osseous canal expansion, thinned pedicles, vertebral scalloping

    • May enlarge, extend through neural foramina

  • T1WI: Isointense→ hyperintense to cord

  • T2WI: Almost always hyperintense to cord

    • Hypointensity at tumor margin = hemosiderin

  • T1WI C+: Intense enhancement

Top Differential Diagnoses

  • Nerve sheath tumor

  • Intradural metastases

  • Meningioma

  • Paraganglioma

Pathology

  • WHO grade I

  • May have local seeding or subarachnoid dissemination

  • Subarachnoid hemorrhage

Clinical Issues

  • Symptoms mimic disc herniation

  • Back pain most common

  • Other issues include paraparesis, radiculopathy, or bladder and bowel dysfunction

Diagnostic Checklist

  • Slow tumor growth may delay diagnosis

  • Always image the conus in patients presenting with back pain

Sagittal graphic shows a multilevel cauda equina myxopapillary ependymoma. Mass is vascular, with old intratumoral hemorrhage
, acute subarachnoid hemorrhage
. Slow tumor growth has enlarged spinal canal and remodeled posterior vertebral cortex
.

Coronal T1WI MR shows a well-delineated, intradural extramedullary mass in lumbar spine
. Lesion is predominantly isointense with cord and nerves. Almost 70% of filum terminale masses are ependymomas, mostly myxopapillary type.

Sagittal T2WI MR reveals an extensive intradural tumor distorting the conus
and cauda equina
. Myxopapillary ependymomas are unique in their intracellular and perivascular accumulation of proteinaceous mucin, which appears T1/T2 hyperintense.

Sagittal T1WI C+ MR exhibits avid homogeneous tumor enhancement
. Note diffuse intradural tumor seeding
. Smaller tumors tend to displace the cauda equina nerve roots, whereas large tumors often compress or encase them.

TERMINOLOGY

Abbreviations

  • Myxopapillary ependymoma (ME)

Definitions

  • Slow-growing glioma arising from ependymal cells of filum terminale

IMAGING

General Features

  • Best diagnostic clue

    • Enhancing cauda equina mass with hemorrhage

  • Location

    • Almost exclusively in conus, filum terminale, or cauda equina

    • Ependymomas outside of CNS are rare

      • –

        Metastases or direct extension of primary CNS lesion after surgery

      • –

        Direct extension to sacrococcygeal area from cord ependymoma or ME

      • –

        Primary presacral, pelvic, or abdominal lesion

      • –

        Primary ME of skin or subcutaneous tissue in sacrococcygeal region

        • □

          Originates from ectopic ependymal remnants

  • Size

    • Usually spans 2-4 vertebral segments

      • –

        May fill entire lumbosacral thecal sac

  • Morphology

    • Well circumscribed

    • Ovoid, lobular, sausage-shaped

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