J Korean Soc Radiol 2018;79(5):294-301 https://doi.org/10.3348/jksr.2018.79.5.294
INTRODUCTION
Subependymomas are rare benign central nervous system tu- mor corresponding histologically to WHO grade I (1). They ac- count for 0.7% of all intracranial tumors (1). They commonly arise in the fourth (50–60%) and lateral ventricles (30–40%) (1).
There are very few cases in which the subependymoma is so large that causes symptoms. Furthermore, they occur very rarely in the spinal cord and only 54 cases have been reported in the literature (1, 2) since the first case was reported by Boykin et al.
(3). To the best of our knowledge, spinal intramedullary subep- endymoma has not been described in the Korean literature. We report two cases of subependymomas, one of which shows atypical appearances at lateral ventricle and the other of which shows rare case of intramedullary subependymoma of the spi- nal cord.
CASE REPORTS
Case 1
A 54-year-old man presented with dizziness for 3 weeks. Diz- ziness was provoked when suddenly standing up. He had no co-morbidities other than dyslipidemia. CT showed a low den- sity tumor at right lateral ventricle with a high density foci (ar- row) on non enhanced CT with minimal enhancement (arrow) on contrast enhanced CT (Fig. 1A, B). MRI revealed large in- traventricular mass with internal cystic component in right lat- eral ventricle, abutting to septum pellucidum. The size of the mass was measured to approximately 3.5 × 2.8 × 3.2 cm. The mass had iso-intensity signal on T1-weighted image (T1WI) and hyper intensity signal on Fluid-attenuated inversion recovery (Fig. 1C, D). There was no lesion indicating extra ventricular infiltration. There were also scattered foci of hypo intensity on susceptibility weighted image (SWI) (Fig. 1E), indicating pres-
Atypical Appearance and Location of Subependymomas:
A Report of Two Cases
비전형적인 모양과 위치를 보이는 상의하세포종: 2개의 증례 보고
Jee Hyeon Lee, MD
1, Eun Soo Kim, MD
1*, Yul Lee, MD
1, Kwanseop Lee, MD
1, Mi Jung Kwon, MD
2, Joon-Ho Song, MD
3Departments of 1Radiology, 2Pathology, 3Neurosurgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea
Subependymomas are rare benign central nervous system tumor which account of 0.7% of all intracranial tumors. Subependymomas show characteristic MR findings according to their location. However, sometimes atypical findings could be found. In addition, subependymomas can occur very rarely in the spinal cord. We report two cases of pathologically confirmed subependymoma, one of which shows atypical appearances in spite of their intraventicular location and the other of which shows rare case of spinal intramedullary subependymoma. We review the clinical symp- toms and radiologic findings of two cases
Index terms
Glioma, Subependymoma Brain Neoplasms Spinal Cord
Received March 28, 2018 Revised May 10, 2018 Accepted June 15, 2018
*Corresponding author: Eun Soo Kim, MD Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 22 Gwanpyeong-ro 170beon-gil, Dongan-gu, Anyang 14068, Korea.
Tel. 82-31-380-5985 Fax. 82-31-380-3878 E-mail: [email protected]
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distri- bution, and reproduction in any medium, provided the original work is properly cited.
heterogeneous enhancement on contrast-enhanced T1WI (Fig.
1F). The patient underwent a craniotomy with resection of in-
diagnosis of subependymoma. The patient was discharged without any post operative event.
Fig. 1. Brain CT and MR images of intraventricular subependymoma in a 54-year-old man with dizziness for 3 weeks.
A. Non enhanced CT shows a low density tumor at right lateral ventricle with a high density foci (arrow).
B. Contrast enhanced CT shows minimal enhancement in the mass (arrow).
C. T1-weighted image reveals a large intraventricular iso-signal intensity mass (arrow) with internal cystic component in right lateral ventricle, abutting to septum pellucidum. The size of the mass is measured to approximately 3.5 × 2.8 × 3.2 cm.
D. Fluid-attenuated inversion recovery shows the intraventricular mass showed high signal intensity (arrow) without evidence of extraventricular infiltration.
A
C
B
D
Case 2
A 50-year-old man presented with a 14 months history of back pain. He also complained of pain at left thigh for 1 years. The pain did not relieved with non-steroidal anti-inflammatory drugs.
There was no abnormal finding at neurological examination.
Sagittal T2-weighted image (T2WI) showed a high signal inten- sity mass with intramedullary location at the thoracic 6 level of spinal cord (Fig. 2A). Axial T2-weighted axial image revealed a high signal intensity mass with clear cut demarcation of the in- terface between the spinal cord and the tumor (Fig. 2B). It was located at right side of the spinal cord with eccentric location.
The mass showed subtle hypointensity on T1WI (Fig. 2C) and no demonstrable enhancement was noted at the mass on con- trast-enhanced T1WI (Fig. 2D, E). There was no evidence of peritumoral edema. Imaging findings suggested the diagnosis of intramedullary tumor, and the differential diagnosis was consid- ered as astrocytoma. T5–T6 total laminectomy was performed and a histological diagnosis was confirmed to subependymoma.
Postoperatively, the patient developed paraplegia and bladder, rectal disturbance. Muscle power assessment of the lower limbs showed Grade 0 immediately after operation. However, at the time of discharge he showed slight improvement in motor exami-
nation but couldn’t stand up yet. Post operative MRI revealed no tumor recurrence after 18 months.
DISCUSSION
Subependymomas are rare benign gliomas with a prevalence of 0.4–0.7% and have been more commonly reported in elderly males with a mean age of 39–59 years (4).
Most subependymomas appear as a lobular, well-defined in- traventricular mass that is hypodense to isodense to brain pa- renchyma with no periventricular extension on CT (4, 5). The majority of subependymomas are solid or solid with cystic com- ponents and contrast enhanced CT usually shows little or no en- hancement (4, 5). Subependymomas are generally presented as a large intraventricular lesion located in the frontal horn and body of the left lateral ventricle which had iso- to hypointensity on T1WI and hyperintensity on T2WI with no enhancement or mild enhancement (4, 5).
Intracranial subependymoma can be divided into supraten- torial and infratentorial according to their location. The typical MR features of supratentorial subependymoma are different compared to that of infratentorial subependymoma. First of all,
E F
Fig. 1. Brain CT and MR images of intraventricular subependymoma in a 54-year-old man with dizziness for 3 weeks.
E. There is also scatted foci of hypo-intensity (arrows) on susceptibility weighted image indicating presence of calcific deposits and/or blood.
F. The axial contrast enhanced T1-weighted image shows heterogeneous enhancement (arrow).
calcification is rare feature of supratentorial subependymoma.
Second, the enhancement pattern is also different depending on its anatomical location in most cases. As we listed in Table 1, Nishio et al. (5) reported 4 lateral ventricle subenpendymoma
and none of 4 them had calcification. And only one of them showed heterogeneous enhancement , while all the other showed scarce or no enhancement. In addition to this report, according to recent study by Abdel-Aal et al. (4), combined re- A
D
B
E
Fig. 2. Spine MR images of eccentric intramedullary subependymoma in a 50-year-old man with back pain and radiating left thigh pain.
A. The sagittal T2WI shows the intramedullary high signal intensity mass (arrow) at the thoracic 6 level of spinal cord.
B. The axial T2WI reveals the high signal intensity mass (arrow) with clear cut demarcated interface between the spinal cord and the tumor and no definite peritumoral edema or infiltration.
C. The mass shows hypo-intensity (arrow) on sagittal T1WIs.
D, E. The sagittal and axial contrast enhanced T1WIs show no demonstrable enhancement (arrow).
T1WI = T1-weighted images, T2WI = T2-weighted image
C
Table 1. Review of the Previously Reported Cases of Subependymoma at Lateral Ventricle Author (Year)Patient No.Age, Y/SexLocation (Level)Clinical Presentation
CT FindingsMRI Findings TreatmentOutcome DensityCalcificationEnhancementT1WIT2WIEnhancementSWI Nishio et al. (2000) (5)
155/MRight septum pellucidum
Headache (7mo), mental dullness (6 mo), uninary incontinence (5 mo), unsteady and slow gait (4 mo) LowNoScarceNot examined
Not examined
Not examined
Not examined
Transcortical (Total removal)
No recurrence 260/MRight septum pellucidum
Headache (9 mo), unsteady gait (5 mo) LowNoNoLow SIHigh SIScarceNot described
Anterior interhemispherric treascallosal (Total removal)
No recurrence 351/MRight septum pellucidum –Corpus callosum, right
NoneLowNoNoLow SIHigh SIScarceNot described
Anterior interhemispheric Transcallosal (Partial removal)
No growing 427/FLateral ventricle
None (hyperprolactinemia) LowNoNoLow SIHigh SIHeterogeneousNot described Frontal craniotomy (Total removal)
No recurrence Adbdel-Aal et al. (2012) (4)
131/MLateral ventricle headache, nausea, vomiting, gait disturbances
Not described
Not described
Not described
Iso-Low SIHigh SIHeterogeneousNot described
Not described in detailsNo recurrence Present case154/MLateral ventricle
DizzinessLowYesMinimalIso SIHigh SIHeterogeneousFoci of low SI Anterior transcallosal (Total removal) No recurrence SI = signal Intensity, SWI = susceptibility weighted imaging, T1WI = T1-weighted image, T2WI = T2-weighted image
Table 2. Review of the Previously Reported Cases of Spinal Intramedullary Subependymoma Author (Year)Patient No.Age, Y/SexLocation (Level)Clinical PresentationMRI Findings TreatmentOutcome T2WIEnhancementBamboo Leaf Sign Kremer et al. (2004) (6)122/FT11-L2Numbness in right footHigh SINo+LaminotomyNo recurrence Yadav et al. (2008) (7)142/MT5-T9Weakness of both lower limbsHigh SINo+Laminectomy (Total excision)No recurrence Jang et al. (2009) (8)137/FT11-12Lower back pain radiating to the right leg with numbness
High SIHeterogeneous-Total laminectomy + adjuvant radiotheraphyNo recurrence Zenmyo et al. (2010) (9)163/FC1-C2Vague burning pain in the left upper armHigh SIFaint-LaminoplastyNo recurrence Krishnan et al. (2012)137/FC3-T4Neck pain and gait disturbanceHigh SIHeterogeneous+Cervical laminoplasty (Subtotal excision)No interval change of residual tumor Iwasaki et al. (2013)157/FT11-T12ParaparesisHigh SINo-Laminectomy + posterior midline myelotomyNo recurrence Wu et al. (2015) (10)119/MC6-T10Bilateral knee pain, lower limb weaknessHigh SINo+Laminoplasty + laminectomy + posterior midline Myelotomy + adjuvant radiotherapy
No interval change of residual tumor 260/FC5-T2Bilateral lower extremity numbnessHigh SINo+Laminoplasty + laminectomy + posterior midline Myelotomy
No interval change of residual tumor 349/MC6-T3Back pain, right lower extremity numbnessHigh SIPartial+Laminoplasty + laminectomy + posterior midline Myelotomy
No interval change of residual tumor Toi et al. (2016) (2)151/MT7-T12Progressive muscle weakness in the right lower extremity, dysesthesia in both lower extremities
High SIFaint+LaminectomyNo recurrence Present case150/MT6Back pain, radiating left thigh painHigh SINo_Laminectomy (Total excision)No recurrence SI = signal Intensity, T2WI = T2-weighted image
ports of 22 lateral ventricular subependymomas show 16 (73%) cases presenting minimal or no enhancement, and 6 (27%) cas- es presenting heterogeneous enhancement. On the other hand, 29 (85%) cases showed heterogeneous enhancement among 34 fourth ventricular subependymomas. Our first case appeared as an atypical appearance of lateral ventricular subependymo- ma showing evidence of calcifications on CT and SWI, which was one of the differentiating features and exceptional hetero- geneous contrast enhancement in spite of its supratentorial lo- cation. In addition to this, most of subependymomas are inci- dentally found and only few of them become symptomatic. The most important factors whether a subependymoma becomes symptomatic or not are location and size (9). Especially, tumors located near the septum pellucidum are more likely to cause symptoms causing obstruction of cerebrospinal fluid pathway and therefore they tends to detect at smaller size (9). However, in spite of its location abutting the septum pellucidum, our case showed relatively large size (largest diameter: 3.5 cm) when it became symptomatic.
Most supratentorial subependymomas have characteristic appearance on MR imaging such as intraventricular mass with lack of calcification and no or minimal contrast enhancement, which differentiates them from other supratentorial intraven- tricular tumors and also from infratentorial subependymomas.
However, the large size, calcifications, high vascularity, hetero- geneous enhancement and presence of symptoms, should not persuade the radiologist to exclude it from his differential diag- nosis.
Spinal subependymomas are much less frequent than intra- cranial subepedymomas. Majority of them were intramedullary and located in the cervical (48%), thoracic (40%), or lumbar re- gion (7%), among 54 cases which have been reported (2). One patient had holo cord subependymoma and location of rest of the 3 cases was not described (2).
Spinal intramedullary subepedymomas on MRI typically show segmental fusiform dilatation of spinal cord, which are hy- pointense to isointense on T1WI, hyperintense on T2WI, and occasionally display faint enhancement after contrast injection (10). The MRI findings of all reported intramedullary cervico- thoracic subependymomas are shown in Table 2. Our results are consistent with those described in the literature. The intra- medullary ependymoma is believed to originate in the wall of
the central canal, and is classified as WHO grade II. In contrast, subependymomas may develop into huge masses and compress the cord severely, causing their characteristic eccentric localiza- tion (10). The majority of spinal subependymoma show eccen- tric location, in contrast to other intramedullary tumor such as ependymoma and astrocytoma showing intramedullary central location. Wu et al. (10) reported 3 cases of spinal subependy- moma and all of them showed eccentric location. Due to its ec- centric location, in 2016 for the first time, Toi et al. (2) reported
“bamboo leaf sign” which may help distinguish this tumor from other intramedullary tumors. For example, Kremer et al. (6) re- ported the case of intramedullary subependymoma at T-spine, which showed steep swelling of the spinal cord displaying
“bamboo leaf sign.” However, in our case there was no steep swelling of the spinal cord (bamboo leaf sign) in spite of its typ- ical eccentric location, unlike most cases reviewed at report of Toi et al. (2). Also, intraspinal subependymomas not always show bamboo leaf sign even if their eccentric location in the spinal cord. Therefore, we should not rule out a subependymo- ma as a differential diagnosis when there is an intramedullary mass in the spine with eccentric location.
Surgical excision is the treatment of choice for both intracra- nial and spinal subependymoma and post-operative radiother- apy is not recommended (1, 8).
In conclusion, we describe here two cases with atypical ap- pearance or rare location. Therefore, we should not exclude sub- ependymoma as a differential diagnosis though its radiologic findings are unusual.
REfERENCES
1. Tacconi L, Johnston FG, Thomas DG. Subependymoma of the cervical cord. Clin Neurol Neurosurg 1996;98:24-26 2. Toi H, Ogawa Y, Kinoshita K, Hirai S, Takai H, Hara K, et al.
Bamboo leaf sign as a sensitive magnetic resonance imag- ing finding in spinal subependymoma: case report and lit- erature review. Case Rep Neurol Med 2016;2016:9108641 3. Boykin FC, Cowen D, Iannucci C, Wolf A. Subependymal
glomerate astrocytomas. J Neuropathol Exp Neurol 1954;13:
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Unusual appearance and presentation of supratentorial sub-
5. Nishio S, Morioka T, Mihara F, Fukui M. Subependymoma of the lateral ventricles. Neurosurg Rev 2000;23:98-103 6. Kremer P, Zoubaa S, Schramm P. Intramedullary subependy-
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8. Jang WY, Lee JK, Lee JH, Kim JH, Kim SH, Lee KH, et al. In-
9. Zenmyo M, Ishido Y, Terahara M, Yamamoto T, Tanimoto A, Komiya S, et al. Intramedullary subependymoma of the cervical spinal cord: a case report with immunohistochemi- cal study. Int J Neurosci 2010;120:676-679
10. Wu Z, Iwanami A, Yasuda A, Mikami S, Toyama Y, Nakamura M. Intramedullary cervicothoracic subependymoma: report of three cases and review of the literature. J Orthop Sci 2015;20:927-934
비전형적인 모양과 위치를 보이는 상의하세포종: 2개의 증례 보고
이지현
1· 김은수
1* · 이 열
1· 이관섭
1· 권미정
2· 송준호
3상의하세포종은 드문 중추신경계 종양으로 두개내 발생하는 종양의 0.7%를 차지한다. 두개내 상의하세포종은 위치에 따라 특징적인 MR 소견을 보여주는데 가끔 비전형적인 소견도 존재할 수 있다. 또한 매우 드물게는 척수내에 발생하기도 한다. 우리는 각각 뇌실내 위치에도 불구하고 비전형적인 소견을 보인 경우와 드물게 척수 내에 나타난 상의하세포종의 경 우, 두 가지 조직학적으로 확진된 상의하세포종 증례를 소개하고 그 임상적 증상과 영상학적 소견에 대해 고찰하려고 한다.
한림대학교 의과대학 성심병원 1영상의학과, 2병리과, 3신경외과
