Subependymoma of the Cerebellopontine

Angle and Prepontine Cistern in a

15-Year-Old Adolescent Boy
K. Koral, R.M. Kedzierski, B. Gimi, A. Gomez and N.K.
Rollins

This information is current as AJNR Am J Neuroradiol 2008, 29 (1) 190-191

of October 9, 2023. doi: https://doi.org/10.3174/ajnr.A0821
http://www.ajnr.org/content/29/1/190
 Subependymoma of the Cerebellopontine Angle
and Prepontine Cistern in a 15-Year-Old
CASE REPORT Adolescent Boy
K. Koral SUMMARY: A case of cerebellopontine angle and prepontine cistern subependymoma in a 15-year-old
R.M. Kedzierski adolescent boy is presented with a review of the literature. Apparent diffusion coefficient values for
subependymoma are reported. Differential considerations for the unusual location of this rare tumor
B. Gimi
are discussed.
A. Gomez
N.K. Rollins

S ubependymomas are rare intracranial neoplasms typically

located in the subependymal regions of the ventricles. The
patients usually present with slowly progressive symptoms, or
was subependymoma. The patient’s symptoms improved gradually
with residual CN palsies and speech difficulty. At 3-year follow-up,
MR imaging of the brain did not show tumor regrowth.
the tumors are incidentally discovered at autopsy.1 The typical
age of presentation is in the fifth or sixth decades.2 We report Discussion
a rare case of subependymoma involving the cerebellopontine
Subependymoma is a rare, low-grade (World Health Organi-
angle (CPA) and prepontine cistern in a 15-year-old adoles-
zation grade 1) glial neoplasm that is typically encountered in
cent boy and describe the subependymoma imaging charac-
fifth and sixth decades of life.1-4 Because of its low-prolifera-
teristics, including apparent diffusion coefficient (ADC)
tive potential, it was suggested that subependymomas may
values.
represent a hamartoma rather than a neoplasm.3
Case Report Subependymomas commonly arise in the ventricular sys-
A 15-year-old adolescent boy presented to the emergency department tem. Infrequently, they are located in the septum pellucidum
with a 4-year history of speech and balance difficulties. More recently, and spinal cord.5,6 The CPA and prepontine cistern involve-
he developed progressive eye movement abnormalities. On examina- ment without extension into the fourth ventricle is uncharac-
tion, he had right partial cranial nerve (CN) VII and right CN VIII teristic of subependymomas. Hoeffel et al4 described 4 cases
palsies, nystagmus, right-sided dysmetria, and hyperreflexia. with extension into CPA, but in all of them the tumors arose
CT of the head showed a noncalcified, large posterior fossa mass from the fourth ventricle. No CPA tumor was present in the 16
resulting in hydrocephalus. MR imaging of the brain demonstrated a subependymomas reported by Ragel et al2 One CPA tumor
solid, exophytic lesion centered at the right CPA and extending ante- was present among the 24 intracranial subependymomas re-
riorly, obliterating the prepontine cistern. The mass measured 6.3 ⫻ ported by Chiechi et al.1
5.7 ⫻ 6.4 cm and showed T1 and T2 prolongation. The lesion did not On CT, subependymomas are well-demarcated hyperat-
arise or extend into the fourth ventricle, which was compressed and tenuated lesions, with calcifications noted in up to 50% of the
displaced posteriorly. Although there was marked displacement of the cases.1,6 On MR, subependymomas are generally isointense or
brain stem, particularly of pons and mesencephalon, no peritumoral hypointense on T1-weighted images and hyperintense on T2-
edema was evident. The chronic nature of the lesion was underscored weighted images with respect to adjacent brain parenchy-
by scalloping of the dorsal surface of the clivus. There was moderate ma.1,2,4 Usually there is no appreciable vasogenic edema of the
hydrocephalus without transependymal resorption of CSF, confirm- adjacent parenchyma. Subependymomas show no enhance-
ing chronicity of ventricular enlargement (Fig 1A, -B). On diffusion- ment or mild-to-moderate enhancement.1,2,4
weighted imaging (DWI), the lesion did not show restricted diffusion.
To our knowledge, ADC values in a subependymoma were
The ADC values were obtained using a circular region of interest with
not published previously. In 2 reports, DWI of subependymo-
a diameter of 10 mm at 5 nonoverlapping locations in the tumor. The
mas was discussed, without reference to ADC values. Both
mean ADC value was 1.34 ⫻ 10⫺3 mm2/s (range, 1.30 –1.39 ⫻ 10⫺3
lesions were in the fourth ventricle, and they were described as
mm2/s, ⫾SD 0.04). The lesion demonstrated minimal punctate en-
isointense/hyperintense on DWI.7,8 Rumboldt et al9 reported
hancement. There was no leptomeningeal tumor spread or spinal
drop metastases.
the use of ADC values in distinguishing pediatric cerebellar
The patient underwent a right-retrosigmoid and far-lateral crani- tumors. In this report, ADC values of 5 ependymomas were
otomy, and the bulk of the tumor was resected. Pathologic diagnosis reported with a mean of 1.10 ⫾ 0.11 ⫻ 10⫺3 mm2/s. Our case
has a mean tumor ADC value of 1.34 ⫾ 0.11 ⫻ 10⫺3 mm2/s,
Received July 25, 2007; accepted after revision August 13. which is slightly higher than those of ependymoma, but not as
From the Departments of Radiology (K.K., R.M.K., B.G., N.K.R.) and Pathology (A.G.), high as those of juvenile pilocytic astrocytoma (JPA).9
University of Texas Southwestern Medical Center at Dallas and Children’s Medical Center, The differential diagnosis of a large CPA mass in a young per-
Dallas, Texas.
son includes ependymoma, JPA, medulloblastoma, atypical ter-
Please address correspondence to Korgun Koral, Children’s Medical Center of Dallas,
Department of Radiology, 1935 Motor St, Dallas, TX 75235; e-mail: korgun.koral@ atoid/rhabdoid tumor, brain stem glioma, choroid plexus tu-
utsouthwestern.edu mors, hemangioblastoma, arachnoid cyst, and epidermoid. A
DOI 10.3174/ajnr.A0821 rare exophytic low-grade brain stem glioma may potentially be

190 Koral 兩 AJNR 29 兩 Jan 2008 兩 www.ajnr.org

 Fig 1. A, Axial T2-weighted image shows a large, solid
hyperintense mass in the right CPA and prepontine cistern,
displacing the fourth ventricle to left. The signal intensity
void of basilar artery is maintained but is entirely circum-
scribed by tumor. B, Coronal contrast-enhanced T1-weighted
image shows the patent basilar artery (arrows) and obstruc-
tive hydrocephalus. On the left, the tumor traverses the
tentorial incisura and displaces the third ventricle to the left.
There is minimal punctate enhancement.

difficult to distinguish from a case of subependymoma similar to 4. Hoeffel C, Boukobza, Polivka M, et al. MR manifestations of subependymo-
mas. AJNR Am J Neuroradiol 1995;16:2121–29
ours. Subependymoma is a very rare pediatric tumor, but lack of
5. Rath TJ, Sundgren PC, Brahma B, et al. Massive symptomatic subependymoma
vasogenic edema in subependymoma may be a distinguishing of the lateral ventricles: case report and review of the literature. Neuroradiol-
feature from the otherwise similar ependymoma. ogy 2005;47:183– 88
6. Jooma R, Torrens MJ, Bradshaw J, et al. Subependymomas of the fourth
References ventricle: surgical treatment in 12 cases. J Neurosurg 1985;62:508 –12
1. Chiechi MV, Smirniotopoulos JG, Jones RV. Intracranial sub- 7. Fontenele GI, Okamoto K, Ito J, et al. Symptomatic child case of subependy-
ependymomas: CT and MR imaging features in 24 Cases. AJR Am J Roent- moma in the fourth ventricle without hydrocephalus. Radiat Med
gen 1995;165:1245–50 2001;19:37– 42
2. Ragel BT, Osborn AG, Whang K, et al. Subependymomas: an analysis of clin- 8. Quadery FA, Okamoto K. Diffusion weighted MRI of haemangioblastomas
ical and imaging features. Neurosurgery 2006;58:881–90 and other cerebellar tumours. Neuroradiology 2003;45:212–19
3. Prayson RA, Suh JH. Subependymomas: clinicopathological study of 14 tu- 9. Rumboldt Z, Camacho DL, Lake D, et al. Apparent diffusion coefficient for
mors, including comparative MIB-1 immunohistochemical analysis with differentiation of cerebellar tumors in children. AJNR Am J Neuroradiol 2006;
other ependymal neoplasms. Arch Pathol Lab Med 1999;123:306 – 09 27:1362– 69

BRAIN
CASE REPORT

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