myxopapillary ependymoma

Myxopapillary ependymomas are a variant type of ependymoma that occurs predominantly in the filum terminale and/or conus medullaris. They represent 13% of all spinal ependymomasand are the most common tumors of the cauda equina region.

Epidemiology

They tend to have an earlier clinical presentation than other spinal ependymomas, with a mean age of presentation of 35 years. There is a slight male predominance.

Clinical presentation

The most common presenting symptoms are low back, leg or sacral pain. Up to 25% of patients may present with leg weakness or sphincter dysfunction.

They may occasionally present as a subarachnoid hemorrhage .

Pathology

Etiology

They are thought to arise from the ependymal glia of the filum terminale.

Location

The vast majority are intradural and extramedullary spinal tumors, occurring in the lumbosacral spine involving the filum terminale and/or conus medullaris. Less commonly, they extend from the lumbar to the thoracic spine . Rarely, they can arise in the cervicothoracic spine or fourth ventricle .

Classification

These are WHO grade I ependymal tumors.

Macroscopic appearance

They are typically lobulated, encapsulated, and oval or sausage-shaped. They often have associated hemorrhage and may calcify or undergo cystic degeneration .

Microscopic appearance

Histologically, they contain papillary elements arranged radially around a hyalinized fibrovascular core, forming perivascular pseudorosettes, with myxoid material between the blood vessel and tumor cells . "Balloons" (rounded eosinophilic PAS positive structures) are sometimes encountered .

Immunophenotype

As is the case with ependymomas generally, myxopapillary ependymomas are GFAP, S100, and vimentin positive . CD99, AE1/AE3 and NCAM1 are also commonly positive .

Radiographic features

Plain radiograph / CT

If they become large, myxopapillary ependymomas may expand the spinal canal, cause scalloping of the vertebral bodies and extend out of the neural exit foramina.

MRI

They are well-defined intradural tumors. Classically, they present when larger and sausage-shaped, spanning more than one vertebral level, but small oval tumors are also seen. Smaller tumors tend to displace the nerve roots of the cauda equina; larger tumors often compress or encase them .

Signal characteristics

• T1
  • usually isointense
  • prominent mucinous component occasionally results in T1 hyperintensity
  • hemorrhage and calcification can also lead to regions of hyper- or hypointensity
• T2
  • overall high intensity
  • low intensity may be seen at the tumor margins because of hemorrhage, called the cap sign (myxopapillary ependymomas are the subtype of ependymomas that are most prone to hemorrhage )
  • calcification may also lead to regions of low T2 signal
• T1 C+ (Gd)
  • enhancement is virtually always seen
  • the enhancement pattern is typically homogeneous. However, they can have a variable enhancement pattern that, in part, depends on the amount of hemorrhage present

Treatment and prognosis

Myxopapillary ependymomas are generally slow-growing and benign. Occasionally, CSF dissemination occurs and multiple lesions are seen in 14-43% cases . Some sacral lesions are locally aggressive and metastasize to lymph nodes, lung, and bone. Aggressive behavior is more commonly seen in children .

They can often be excised completely. In these cases, the prognosis is excellent, with 5-year-survival over 98% .

If the tumor has extended to the conus medullaris, resection is often incomplete, with greater risk of local recurrence, and there is a greater risk of neurologic deficit .

Differential diagnosis

Differential diagnosis of a small conus and filum terminale myxopapillary ependymoma includes:

• schwannoma
• paraganglioma

Differential diagnosis of a large myxopapillary ependymoma that causes sacral destruction:

• aneurysmal bone cyst: involving the spine
• chordoma
• giant cell tumor: involving the spine

See also

• intradural spinal mass lesions-an approach

Siehe auch:

• Aneurysmatische Knochenzyste
• Ependymom
• Chordom
• Astrozytom
• Riesenzelltumor
• spinal paraganglioma
• spinale Schwannome
• Cauda equina Lipom
• intradural spinal mass lesions - an approach
• spinale kavernomatöse Malformationen
• spinales Ependymom
• ependymoma vs astrocytoma of the spinal cord
• spinales Ependymom des Filum terminale
• Neoplasien der Cauda equina
• intramedulläres Ependymom

und weiter:

• Schwannom
• neoplasms of the spinal canal
• WHO-Klassifikation der Tumoren des zentralen Nervensystems
• Superfizielle Hämosiderose der Leptomeningen
• spinales Hämangioblastom
• spinal myxopapillary ependymoma
• spinal nerve sheath tumours
• scalloping Wirbelkörper
• spinal primitive neuroectodermal tumour
• intradurale extramedulläre Tumoren
• malignant ependymoma
• intraspinale Tumoren
• Riesenzellependymom