Keywords
anaplastic - cortical - pediatric ependymoma
Introduction
Ependymomas are tumors derived from ependymal cells lining the ventricles or from
the central canal of the spinal cord. It represents 3 to 9% of all neuroepithelial
neoplasms, 6 to 12% of all pediatric brain tumors, and almost one-third of all brain
tumors in patients younger than 3 years. Approximately 40% of ependymomas are supratentorial,
whereas 60% are infratentorial in location. Ependymomas may manifest at any age (documented
age ranges from 1 month to 81 years) with no sex predilection. Posterior fossa ependymomas
are common in children (mean age: 6 years) and supratentorial ependymoma generally
manifests in an older age group (mean age: 18–24 years). Although the lesion arises
from the ventricular system, it can grow beyond the ventricles, through the cerebral
tissue, representing the extraventricular form. It can exist in extraventricular structures,
without any connection to ventricular system, representing the rare group of ectopic
ependymoma. In the literature not more than 30 cases have been reported, of which
15 were diagnosed purely cortical and only 7 cases were anaplastic (grade III) lesions
[Table 1].[1] We report a rare case of solitary cortical pediatric anaplastic ependymoma.
Table 1
All reported cases of pure cortical supratentorial grade III ependymomas
|
Series
|
Cases
|
Grade
|
|
Davis et al[2]
|
1
|
III
|
|
Alexiou et al[3]
|
1
|
III
|
|
Hamano et al[4]
|
1
|
III
|
|
Akyuz et al[5]
|
1
|
III
|
|
Romero et al[1]
|
1
|
III
|
|
Kharosekar et al[6]
|
1
|
III
|
|
Present study
|
1
|
III
|
Discussion
Although approximately half of the supratentorial ependymomas arise from the wall
of third or lateral ventricles and are purely intraventricular, few may extend through
adjacent cerebral tissue, representing extraventricular forms of ependymoma. Only
few cases occur in distant places of the ventricular system, representing rare cases
of ectopic lesions. It is speculated that ectopic ependymomas may arise from embryonic
rests of ependymal tissue trapped in the developing cerebral hemispheres. Supratentorial
ependymoma grows into third or lateral ventricle; it is predominant involving the
brain parenchyma at the diagnosis. Hamano et al reported that 83% of supratentorial
ependymomas are in the cerebral parenchyma. Owing to its parenchymal location, the
supratentorial ependymoma tends to be larger in size at the diagnosis.
Roncaroli et al found that 94% of supratentorial tumors manifest with a size larger
than 4 cm and often contain a cystic component. Despite their large size in the cerebral
hemispheres, symptoms are relatively mild until a later stage of presentation. Symptoms
of raised intracranial pressure such as headache and vomiting are common, whereas
focal signs as limb weakness and seizures are less prevalent. The principal differential
diagnosis of extraventricular supratentorial ependymoma must include astrocytoma (both
low-grade and glioblastoma multiforme), supratentorial primitive neuroectodermal tumor
(PNET), ganglioglioma, gangliocytoma, and oligodendroglioma. They have no typical
imaging features or findings; hence every lesion, with extension to the ventricular
system, should make us suspicious of this fact. They are iso- to hypodense attenuations
to surrounding normal brain tissue at nonenhanced CT. They are iso- to hypointense
attenuations relative to normal white matter on nonenhanced T1-weighted magnetic resonance
(MR) images and hyperintense attenuations on T2- and proton-density–weighted MR images.
Foci of signal heterogeneity within a solid neoplasm represent methemoglobin, hemosiderin,
necrosis, or calcification, which is very common in this tumor (40–80% of cases).
Ependymomas can display variable contrast enhancement behavior but generally enhance
moderately intensely at both CT and magnetic resonance imaging (MRI), with central
areas of necrosis.[1]
Histologically, the tumor cells are characteristically organized in perivascular pseudorosettes
and, less commonly, ependymal rosettes. Although ependymomas are moderately cellular
tumors with rare mitotic figures (World Health Organization [WHO] grade II lesions),
our patient had a more aggressive tumor, classified as WHO grade III. Fewer than five
ectopic anaplastic ependymomas were reported previously.
The best treatment is radical resection, because it appears that tumor resectability
is the most important factor associated with recurrence. Solitary cortical (ectopic)
tumors are comparatively easier to approach than lesions with connection to ventricles,
having better outcome. Postoperative radiotherapy should be administered in every
case of partially resected ependymomas or anaplastic tumors. At present chemotherapy
and prophylactic cranio-spinal irradiation are not indicated as adjuvant treatment.
Age at presentation is also a significant prognostic factor. Patients younger than
3 years have a significantly worse outcome than older children or adults. The last
prognostic variable is the duration of symptoms before diagnosis. Patients with symptoms
before diagnosis less than 1 month have a worse outcome than those with a more protracted
course.
Prognostic factors of ependymomas that positively contribute to progression-free survival
and longer survival are still elusive, even in histologic characteristics. The 5-year
progression-free survival rate for children overall is approximately 50% and 10-year
survival rates for adults are 57.1% and 45%, respectively. Only total tumor resection
is considered as a reliable prognostic factor for predicting longer survival time.
Of patients with no radiologic evidence of residual tumor, 75% ± 15% will remain tumor
free after 5 years as opposed to the group of patients with residual disease in which
progression cannot be stopped.
An increased risk of recurrence was reported with a high histologic grade, incomplete
resection, and a Karnofsky performance status that is 80 or less.[7]
[8]
Our patient was treated with radical surgery and subjected to postoperative radiotherapy,
due to anaplastic grade of tumor. There was no evidence of gross residual tumor at
postoperative imaging. The patient had a good recovery of neurologic symptoms. His
left hemiparesis improved. Now he is regularly being followed in our outpatient clinic.
Consent
Written informed consent was obtained from the patient for publication of this case
report and accompanying images.
