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Case Report
Pedunculated intraventricular subependymoma: Review of the
literature and illustration of classical presentation through a
clinical case
Silvia Hernandez-Duran 1 , Tze-Yu Yeh-Hsieh 1,2 , Carlos Salazar-Araya 1,5
'University of Costa Rica, School of Medicine, Ciudad Univcrsitaria Rodrigo Facio, San Pedro de Montcs de Oca, 2 Departmcnts of Neurological Surgery, Hospital
San Juan de Dios, Paseo Colon, 5 Ncurological Surgery, Hospital Dr. Rafael Angel Caldcron Guardia, Calle 17, San Jose, Costa Rica
E-mail: *Silvia Hcrnandcz-Duran - drahcrnandczduran@gmail.com;Tsc-YuYch-Hsich - tyychh@gmail.com Carlos Salazar-Araya - cesancx@racsa.co.cr
*Corrcsponding author:
Received: 29 January 14 Accepted: 23 April 14 Published: 30 July 14
This article may be cited as:
Hernandez-Duran S, Yeh-Hsieh T, Salazar-Araya C. Pedunculated intraventricular subependymoma: Review of the literature and illustration of classical presentation through a
clinical case. Surg Neurol Int 20I4;5:I 17.
Available FREE in open access from: http://www.surgicalneurologyint.com/text.asp?20 1 4/5/ 1 / 1 17/1 37837
Copyright:© 2014 Hernandez-Duran S.This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Background: Subependymomas are rare benign, noninvasive tumors, classified by
the World Health Organization as low grade neoplasms. International data estimate
their frequency between 0.2% and 0.7% of the intracranial tumors, and they usually
are an incidental finding in autopsies. Preferably located in the fourth ventricle,
these tumors tend to become symptomatic when they cause hydrocephalous by
obstructing cerebrospinal fluid circulation.
Case Presentation: We present the case of a morbidly obese, hypertense,
and diabetic patient, who presented with symptoms of gait ataxia, sphincter
incontinence, and dysartria in relation to a pedunculated subependymoma in the
left lateral ventricle. He underwent a biparietal craniotomy with a microscopic
microsurgical approach, through which gross total resection was achieved. No
perioperative complications ensued.
Conclusions: Given their benign behavior and their excellent response to surgical
treatment, subependymomas should be promptly diagnosed and surgically treated
to avoid possible neurological damage when they become symptomatic.
KeyWords: Gait ataxia, intraventricular mass, pedunculated, subependymoma
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DOI:
10.4103/2152-7806.137837
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INTRODUCTION
Subependymomas are rare, benign, noninvasive tumors
of ependymal origin. Internationally, their frequency is
estimated between 0.2% and 0.7% of intracranial tumors,
and they are usually incidental findings in autopsies.' 101
These slow-growing neoplasms occur more frequently
in middle-aged men, and they are preferably located in
the fourth ventricle.' 15 ' When they become symptomatic,
these tumors can present with symptoms secondary to
cerebrospinal fluid (CSF) obstruction and intracranial
hypertension, such as positional headache, nausea,
vomiting, papilledema, and alterations in consciousness;
or secondary to the compression of adjacent structures,
such as sensory or motor disturbances, or seizures.' 616 '
Surgical treatment of these lesions, either by means
of partial or total resection, usually alleviates the
symptoms, and it can provide good long-term tumor
control.' 71 We now present the case of a patient who
suffered from symptoms of intracranial hypertension due
to a pedunculated subependymoma of the left lateral
ventricle.
Surgical Neurology International 20 1 4, 5: 1 17
CASE REPORT
A 51-year-old, morbidly obese male, with past medical
history of long-standing hypertension and type 2 diabetes
mellitus, consulted because of 3 weeks of gait ataxia,
sphincter incontinence, and episodic dysarthria of several
minutes duration. Initially, the patient was managed
by the Neurology Service, who observed wide-based
gait, inability to perform tandem gait, globally reduced
reflexes and glove and stocking sensory disturbances.
Complementary studies revealed polyneuropathy, likely
of diabetic origin, and vetebrobasilar insufficiency. The
patient was therefore managed as an ischemic syndrome.
Nevertheless, the patient also underwent a computerized
tomography (CT) scan, and magnetic resonance imaging
(MRI), which showed an isodense lesion [Figure 1]. The
latter appeared to be located in the left lateral ventricle,
where it obstructed the foramen of Monro, thus creating
mild hydrocephalus. Subsequently, the patient was
transferred to the Neurosurgical Department with the
presumptive diagnosis of left ventricle neurocytoma for
further management.
Because the patient suffered progressive clinical decline,
characterized by dysphasia and paresis of the lower
extremities, we placed a ventriculostomy to control his
malignant intracranial hypertension. Twenty-four hours
later, the patient underwent biparietal craniotomy. We
performed a transcallosal approach with microsurgical
technique; an anterior longitudinal callostomy was
performed, and a fibroelastic intraventricular mass
of whitish coloration, limited by a vascular pedicle,
measuring approximately 6x3x4 cm was resected.
Figure I : (a)T I -weighted coronal view. Hypointense nodular image
in the floor of the left lateral ventricle, producing mild-moderate,
noncommunicating hydrocephalus, (b) T I -weighted sagittal
view. Note the involvement of the brainstem, which explains the
symptoms of the patient, (c) T I -weighted axial view showing a
nodular, hypointense lesion with small cystic areas in its interior,
(d) Axial view, FLAIR. Note the absence of perilesional edema, and
the lack of contrast enhancement
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Gross total resection was achieved, and there were no
postoperatory complications.
Biopsy revealed a tumor with small, rounded nuclei and
scarce cytoplasm, and cell groups surrounded by abundant
fibrillary matrix and cystic areas. Immunohistochemistry
was positive for glial fibrillary acidic protein (GFAP) and
negative for neurospecific enolase, which was compatible
with grade I subependymoma, according to the World
Health Organization (WHO) classification [Figure 2].
The patient is currently asymptomatic of his neurosurgical
condition, with complete resolution of his speech and
sphincter disorders, and he is completing rehabilitation
at the Costa Rican National Rehabilitation Centre for
his sensory and motor deficits in the lower extremities.
Postoperative imaging did not show tumor recurrence a
year after surgery.
DISCUSSION
Initially described by Scheinker in 1945, [18 '
subependymoma is a rare, low-grade intracranial tumor,
according to the WHO classification. The largest
case series published to date describe an incidence of
0.4-0.7%, which is larger in middle-aged or senior males,
with a mean age of presentation between 48.5 and
53.6 years.' 5 ' 12,16 ' 19 ' Epidemiological^, our patient coincides
with the international observations reported in the literature.
The fourth ventricle and the lateral ventricles are among
the most common locations of subependymomas, with
approximate incidences of 60% and 40%, respectively.
Nevertheless, the lesions that tend to express
themselves clinically are those located in the lateral
Figure 2: (a) Gross anatomy of resected tumor, showing a
fibroelastic, whitish mass, (b) H and E stain of the mass, exhibiting
the characteristic rounded cells with small nuclei and scarce
cytoplasm over an abundant fibrillary matrix and cystic spaces.
Note the absence of atypical mitoses, (c) Immunohistochemistry
stain for neurospecific enolase, showing negativity in the majority of
the cells, (d) Immunohistochemistry stain for glial fibrillary acidic
protein (GFAP), exhibiting strong positivity
Surgical Neurology International 20 1 4, 5: 1 17
ventricles.' 3 ' Tumors located on the septum pellucidum
and the foramen of Monro are more prone to cause CSF
obstruction, and typical symptoms include headaches,
nausea, vomiting, seizures, ataxia, and vertigo.' 3 ' 4 ' 12,18 ' The
size of the lesion also plays a very important role in the
clinical expression of subependymomas; Akamatsu et al.
found that the majority of symptomatic tumors had a
diameter of approximately 4 cm, whereas asymptomatic
ones measured 0.8 cm on average.' 11 In their retrospective
analysis of subependymomas in the lateral ventricles,
Maiuri et al. confirmed these data.' 131 Accordingly,
our patient presented with symptoms of intracranial
hypertension and gait ataxia, and his tumor measured
approximately 5 cm in diameter, which is compatible
with the data described in the literature.
Radiologically, the appearance of subependymomas can
vary depending on their location. According to several
studies, subependymomas in the lateral ventricles are
reported as well-defined, isodense or hypodense nodular
images, and they evince minimal contrast uptake.' 2,11 '
Imaging differential diagnosis includes ependymomas.
One of the factors contributing to their differentiation
is that the former ones do not usually present
transependymal extension or perilesional edema, whereas
the latter ones, in addition to showing contrast uptake,
do evince the aforementioned characteristics.''' However,
there are no pathognomonic imaging signs for one tumor
or another, and other differential diagnoses include
choroid plexus papilloma, neurocytoma, and giant cell
subependymal astrocytoma. In our case, imaging showed
an isodense nodular lesion, without perilesional edema,
and the first diagnostic possibility was a neurocytoma.
These tumors also have predilection for the lateral
ventricles, and they can be mistaken for subependymomas
because they are isointense in their solid portions on
MRI. Furthermore, they tend to present with intracranial
hypertension of a few months of course.' 8 '
Macroscopically, subependymomas present as fibroelastic,
whitish nodules.' 191 One of the intraventricular
subependymomas is their growth toward the lumen,
with a marked separation between the neoplasm and the
normal brain parenchyma. This makes the differentiation
between subependymomas and ependymomas easier,
since the latter tend to infiltrate the brain parenchyma,
while also having ill-defined borders.' 13 ' The macroscopic
characteristics of the tumor of our patient coincided with
these classical descriptions. One of the particularities of
the case described is that the tumor was attached to the
ventricular wall by a vascular pedicle. To date, only five
cases of pedunculated subependymomas in the lateral
ventricles have been reported. I 91421 ' It is important to
note that in those cases, as well as in ours, the presence
of this pedicle made the delimitation of the tumor during
the operation much easier, and it became a factor that
contributed to the gross total resection of the mass.
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Histogenesis of subependymomas is a controversial topic,
and several researchers have proposed different cells of
origin. Subependymal glia, astrocytes of the subependymal
plate, and ependymal cells themselves have all been
postulated as likely precursors to subependymomas, but
there are not conclusive data.' 4 ' In spite of this discussion
regarding the origin, the histology of subependymomas
is well characterized. Nidi of rounded cells with a dense
gliofibrillary matrix are classical, and focal microcystic
degeneration is not a rare finding, predominantly in
lesions located in the lateral ventricles.' 16 ' In areas
of higher cell density, nuclei are sometimes oriented
around small-caliber vessels, forming pseudo-rosettes.' 17 '
Immunohistochemistry of subependymomas is positive
for GFAP ST 00 protein, and vimentin.' 20 ' Markers such
as neurospecific enolase, which are commonly positive
in neural and neuroendocrine cells, are negative in
subependymomas, as well as the markers for mitotic
activity MIB-1 and Ki-67.' 16 ' The biopsy of our patient
showed small, rounded cells on a fibrillary matrix with
areas of microcysts, as well as positivity for GFAP, which
are all compatible findings with this type of tumor.
The treatment of symptomatic subependymomas is
complete surgical excision.' 101 Nevertheless, partial resection
of these tumors also has favorable results and is acceptable
if they are located near critical areas that could become
endangered during the surgery;' 6 ' the surgical goal should
be to restore normal CSF flow. Prior to microsurgical
techniques, perioperative mortality rates reached up to
28.8%. ' 3 ' Currently, with technological and neurosurgical
advances, this is just an anecdotal fact, and patients
rarely experience surgery-related complications. I 7 ' B ' b > 17 ]
Our patient also underwent a craniotomy without any
complications.
In conclusion, subependymomas are rare intracranial
tumors of benign behavior. Nevertheless, their size
and location can produce symptoms because of CSF
obstruction or parenchymal irritation. Even though
the imaging characteristics are not pathognomonic,
these neoplasms have a distinctive histology. Because of
their good prognosis and excellent response to surgical
management, prompt and accurate diagnosis is vital to
provide our patients with good outcomes.
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