Laboratory Studies
Laboratory studies are not helpful for diagnosis.
Imaging Studies
See the list below:
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MRI is the diagnostic tool of choice. [2] It reveals discrete, heterogeneous masses with variable enhancement (see the images below).
MRI, T2-weighted image, axial view, showing mixed (isodensity and hyperdensity) heterogenous nature of the tumor with some peritumoral edema.
MRI, T1-weighted image, without contrast, sagittal view, showing the posterior fossa location, mixed (hypodensity and isodensity) signal intensity and tending to grow out of the fourth ventricle.
See the list below:
Evidence of calcification, necrosis, and cystic change are occasionally seen; hemorrhage is rare.
The tumor characteristically displaces rather than infiltrates brain parenchyma with minimal peritumoral edema.
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CT scan is used in emergency situations, although its resolution is inferior to that of MRI. The CT appearance of ependymoma varies, but calcification is more evident on CT scan.
CT scan without contrast, axial view, demonstrates mixed but predominantly hyperdense tumor in the posterior fossa with severe obstructive hydrocephalus.
CT scan with contrast, axial view shows moderately intense contrast enhancement (compare with the previous image).
Procedures
See the list below:
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Ventriculostomy is not required preoperatively because patients are usually stable. In fact, it should be avoided if possible because of the potentially fatal risk of upward herniation or hemorrhage within the tumor with brain stem compression.
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Lumbar puncture is also contraindicated because of a similar risk of downward (tonsillar) herniation preoperatively.
Histologic Findings
The presence of a classic, well-circumscribed lesion with moderate cellularity, punctuated by areas of an acellular, fibrillary zone (perivascular pseudorosettes) is common. Variants include the following:
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Clear cell type with perinuclear halo
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Papillary type with an extensive epithelial component
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True rosette formation
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Rare melanotic type containing lipofuscin and no melanin pigment
Current World Health Organization (WHO) classification grades tumors as follows:
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Subependymoma and myxopapillary tumors - Grade 1
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Ependymoma - Grade 2
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Anaplastic ependymoma - Grade 3
Only 10% of ependymomas metastasize to other areas of the neuraxis; these metastases are almost always associated with tumor recurrence at the primary site, which emphasizes the importance of local control.
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CT scan without contrast, axial view, demonstrates mixed but predominantly hyperdense tumor in the posterior fossa with severe obstructive hydrocephalus.
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CT scan with contrast, axial view shows moderately intense contrast enhancement (compare with the previous image).
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MRI, T2-weighted image, axial view, showing mixed (isodensity and hyperdensity) heterogenous nature of the tumor with some peritumoral edema.
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MRI, T1-weighted image, without contrast, sagittal view, showing the posterior fossa location, mixed (hypodensity and isodensity) signal intensity and tending to grow out of the fourth ventricle.
