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Surgical Neurology International 


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James I. Ausman, MD, PhD 

University of California, Los Angeles, CA, USA 

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 -;Tsc-YuYch-Hsich - Carlos Salazar-Araya - 
*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: 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. 


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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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 

Surgical Neurology International 20 1 4, 5: 1 17 

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 

http://www.surgicalneurologyint.eom/content/5/ 1 / 1 1 7 

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. 


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 

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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