They are predominantly intraventricular and
account for 1%-3% of all primary brain tumors.
In children, they constitute 10% of
intracranial tumors and are third in frequency after astrocytoma and
Some authors have found
a predominance in the first two years of life. However, congenital
ependymomas are very rare and they are often malignant, and in most cases,
located above the tentorium.
A second incidence peak
is found between the third and fifth decade.
Since Bailey and
Cushing’s in 1926, a lot of classification and grading systems were
ependymomas as follows:
Ependymoma (grade II) - Cellular,
Papillary, Clear cell, and Tanycytic
Anaplastic ependymoma (grade III)
Myxopapillary ependymoma (grade I)
Subependymoma (grade I)
are rare and malignant,
with distinct ependymal differentiation, and included in the group of
are 1) Ependymomas, 2) Anaplastic ependymomas, and 3) Subependymomas.
ependymomas are almost exclusively located in the region of the cauda
equina and originate from the filum terminale.
Ependymomas are thought to arise from the
ependymal epithelium of the ventricles and central canal. In children,
posterior fossa is the most common site, whereas it is equally distributed
through out the CNS in adults. Floor of the fourth ventricle is the most
common intraventricular location, followed by the lateral and third
Tumors which originate at the floor of the fourth ventricle may grow
through the foramen of Magnendie into the cisterna magna and furthermore,
through the foramen magnum into the upper cervical spinal canal as far
down as the level of C5. Ependymomas which arise from the medullary velum
at the lateral recess may extend through the foramina of Luschka into the
extraventricular ependymomas originate, probably as a consequence of
embryonal disturbance in the folding of the neural tube, from nests of
ependymal cells incorporated into the parenchyma of the cerebral
ependymomas are often cystic and malignant, with increasing
malignancy the further from the ventricle. These anaplastic tumors
arise most frequently in children, whereas the typical ependymomas at
the foramen of Monro usually occurs in juveniles and is characterized
by an absence of cellular pleomorphism and mitoses.
this tumor is distinct from the central neurocytoma of the same
Ependymomas of the
septum pellucidum may extend into both lateral ventricles, the third
ventricle, and the aqueduct. Ependymomas of the sella turcica arise
from the infundibulum or ependymal cell nests in the posterior
they occur in the second to fourth decades. Spinal ependymomas are
intramedullary and often found in the lumbosacral region. At times,
they extrude from the conus medullaris and remain suspended amongst
the roots of the cauda equina. They are characterized histologically
by a myxopapillary appearance. These tumors are
particularly benign, made up of small monomorphic cells, and have a
better prognosis with longer postoperative survival than ependymomas
of the brain.
ependymomas are firm, pale to reddish in color, nodular, partially
well demarcated, and occasionally lobulated. Cellular, epithelial, and
papillary variants have been
(H&E)- characteristic pseudo rosettes and
vascular elements surrounded by an acellular zone(arrow)
Myxopappilary ependymoma (H&E)-Perivascular
orientation of cells forming pseudo rosettes, rare true rosettes and
cystic spaces containing mucinous
Histologically, there is perivascular
pseudorosettes and true ependymal rosettes. These are seen as rosette like
arrangements of cells with ependymal differentiation. Electron microscopy
reveals these vascular elements surrounded by an acellular zone. Presence
of pleomorphism, increased cell density, and mitosis suggest anaplasia.
There are numerous
variants including common cellular, papillary and clear cell and the
uncommon tanycytic, a fibrillar variant. They are not of clinical
characteristically GFAP positive by
cases have been identified, but the cause of most cases remains unknown.
Cytogenic analysis has
characterized the loss of chromosome 22q as the most common genetic
abnormality. As more than 50% of them have lost or altered chromosome 22q
sequences, the possibility exists that a tumor suppressor gene important
in ependymomas is located on this chromosome.
Intraventricular ones present with features
of hydrocephalus. Cranial
neuropathy can occur in 25% of cases, due to compression or invasion of
the floor of the fourth ventricle. Spinal seeding is suspected in the
presence of backache and radicular symptoms.
Hemispheric ones usually with seizures and
Spinal cord tumors present with signs and
symptoms of an
Radiologically, the CT reveals an iso to
hypodense enhancing peri/intra ventricular lesion with different degrees
of calcifications, necrotic and cystic changes. It is iso to hypodense on
T1 and hyperdense on T2 MRI images. Hemorrhage is reported in 10% of
cases. A tumor-vermis cleavage plane in a posterior fossa tumor that is
isodense on CT is highly suggestive of ependymoma.
Surgical excision and post operative
irrradiation have been the mainstay of treatment.
Uncontrolled studies suggest that total
surgical resection offers long term remission. Second stage
surgery, if needed, has been recommended to to achieve total excision.
Recent advances in surgical tools, intraoperative imaging, and
electrophysiological monitoring have greatly helped the surgeon in his
goal of total excision.
Regardless of location, craniospinal
radiation is advocated both for cases with evidence of spinal
seeding and for high grade ones. In the absence of spinal seeding, some
consider spinal radiation less useful.
Most surgeons add cervical radiation in all
infratentorial cases, although not supported by controlled studies.
traditionally considered to be one of the most radiosensitive brain
tumors. Furthermore, low grade ependymomas represent the most
radioresponsive tumors within the glioma group. Although the need for
postoperative high-dose radiation therapy to achieve local tumor control
is generally agreed upon, there remains a controversy as to the extent of
irradiation. Recent studies of postoperative radiation therapy did not
reveal an improvement in survival by additional prophylactic spinal
irradiation. Thus, local control remains the main therapeutic challenge in
the treatment of intracranial ependymomas.
Recommended doses are
50-60Gy for the primary tumor, 45-60Gy for whole brain irradiation and
30-40Gy for the spine. Children should receive 80% of adult doses. A few
study groups use interstitial irradiation for the treatment of ependymomas.
However, the role of
radiotherapy in low grade cases where total tumor resection
has been achieved remains
Ependymomas have been
reported to be relatively less responsive to chemotherapy.
Responses have been documented to nitrosoureas and vincristine. However,
despite a variety of protocols, improvement of progression free interval
by chemotherapy in addition to surgery and radiotherapy has not yet been
indication for adjuvant chemotherapy is mostly restricted to recurrences
of anaplastic ependymomas in childhood.
Use of stem cells to
enhance the effectiveness of chemotherapy is being studied.
Genetherapy and immunotherapy are under
The prognosis has improved recently. With
complete excision, 5 year survival rates of 37% to 69%.
The prognosis is poorer in the very young, in
recurrences and in anaplastic variants.
The main cause of death in ependymomas patients is recurrence at the
primary tumor site. Median survival time after diagnosis of spinal seeding
is 6 months.
anaplastic ependymomas metastasize most frequently.
Nearly two thirds of
spinal metastases previously reported originated from an anaplastic
According to autopsy
data, spinal seeding can be expected in 25% of cases subsequent to surgery
of the primary tumor.
is rare; they are usually from the supratentorial ones, and carry worse
They are also called subependymal giant cell
These are thought to be derived from glial
elements of the subependymal tissues found just beneath the ependymal
epithelial tissues found just beneath the ependymal epithelial layer. They
are slow growing, intraventricular tumors whose diagnosis is most commonly
made in adults, particularly in older men.
occurrences has been described.
Subependymomas are most
often asymptomatic and incidentally found at autopsy.
They can be supratentorial (27%),
infratentorial (71%),or cervicothoracic(2%). Lateral ventricles is the
most common site, with obstruction at foramen munro and resultant
CT reveals an heterogeneous iso to
hypodense intraventricular mass, with variable enhancement. The
heterogeneity is due to cystic and calcific changes. It is hypo to
isodense on T1, and hyperdense on T2 MRI images.
Unlike ependymomas, there is no
Grossly, they are lobulated, well
circumscribed, nonencapsulated mass, with an intraventricularly
directed growth pattern that is expansile rather than infiltrative.
Histologically, they resemble
normal subependymal structures. Both ependymal and astrocytes are
reveals GFAP positivity.
The presence of ependymal cells suggest
an aggressive nature, and GFAP staining may be negative.
These SGAs may not be associated with Tuberous sclerosis.
Management includes observation of
Those causing hydrocephalus need to be
excised through a transcortical or transcallosal approach;
the aim is to reestablish the CSF drainage; persistent hydrocephalus
may need a shunt procedure. Presently, there is no role for
radiotherapy or chemotherapy.
The patients with Tuberous sclerosis may
have associated with cardiac abnormalities, and hence require a pre
Outcome is favorable, so long as the
hydrocephalus is adequately managed.
(H&E)- typical cellular heterogenicity
with large pyramidal like giant cells(arrow)
are admixed with spindle shaped and smaller fibrillated astrocytes.