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| LETTER TO EDITOR |
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| Year : 2012 | Volume
: 60
| Issue : 1 | Page : 111-113 |
Supratentorial extra-axial anaplastic ependymoma mimicking a meningioma
Vandita Singh1, Mazda K Turel2, Geeta Chacko1, Vivek Joseph2, Vedantam Rajshekhar2
1 Department of Neurological Sciences, Section of Neuropathology, Christian Medical College, Vellore, India
2 Department of Neurosurgery, Christian Medical College, Vellore, India
| Date of Submission | 04-Oct-2011 |
| Date of Decision | 04-Oct-2011 |
| Date of Acceptance | 05-Dec-2011 |
| Date of Web Publication | 7-Mar-2012 |
Correspondence Address:
Vivek Joseph
Department of Neurosurgery, Christian Medical College, Vellore
India
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 22406799 
How to cite this article:
Singh V, Turel MK, Chacko G, Joseph V, Rajshekhar V. Supratentorial extra-axial anaplastic ependymoma mimicking a meningioma. Neurol India 2012;60:111-3 |
Sir,
Ependymomas account for 1.9% of all primary brain tumors and 3.1% of all gliomas. [1] Extra-axial supratentorial ependymomas (EASE) are radiologically similar to meningiomas, and are rare with only five cases reported [Table 1]. [2],[3],[4],[5],[6] We report a case in the subarachnoid, plane, the radiological features of which mimicked a falx meningioma. | Table 1: Reported cases of extra-axial supratentorial ependymomas[2],[3],[4],[5],[6]
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A 35-year-old male presented with a four-month history of multiple episodes of right upper limb partial motor seizures and a single secondary generalized seizure. Examination revealed no neurological deficits. Magnetic resonance imaging (MRI) brain showed a well-defined, enhancing, 1.8 × 1.4 × 1.5 cm mass in the middle third of the falx on the left side [Figure 1]. The tumor was adjacent to the motor cortex. Considering the preoperative diagnosis of a meningioma, small size of the tumor and its proximity to the motor cortex, the option of stereotactic radiosurgery was strongly suggested to the patient. He however, opted to undergo surgery, in spite of being aware of the risk of lower limb weakness. The tumor was approached using a left parietal craniotomy. At surgery, the tumor was found to be free from the falx. It had a good subarachnoid plane with the surrounding brain and was excised radically. The patient developed a right foot drop following surgery. He received postoperative radiation therapy (54 Grey over 30 fractions). Histology and immunoprofile of the tumor was typical of an ependymoma. E3 ubiquitin-protein ligase (MIB-1) labeling index was 40%. There was brisk mitotic activity (up to 20/10 hpf), with no microvascular proliferation or necrosis [Figure 2]. Tumor cells were immunopositive for glial fibrillary acidic protein (GFAP) [Figure 3], S-100, and exhibited dot-like cytoplasmic positivity for epithelial membrane antigen (EMA), all characteristic of ependymoma [Figure 4]. Tumor cells were negative for pancytokeratin and CAM5.2, thus excluding metastatic carcinoma. There were no histological features of meningiomas such as intracytoplasmic-nuclear inclusions and whorls. At one-year follow up, the patient's right foot drop had recovered completely and a contrast computed tomography (CT) scan showed no evidence of residual tumor [Figure 5]. | Figure 1: (a) T2-weighted axial MR image of the brain showing a hyperintense 1.8 × 1.4 × 1.5-cm tumor along the falx. (b) T1-weighted gadolinium-enhanced image showing the enhancing tumor with a broad base on the falx
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 | Figure 2: High-power photomicrograph shows perivascular ependymal pseudorossettes (arrow) and an occasional true ependymal rossette, H and E, × 400
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 | Figure 3: High-power photomicrograph shows immunohistochemical positivity of the tumor cells with GFAP, × 400
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 | Figure 4: High-power photomicrograph shows dot-like cytoplasmic immunohistochemical positivity of the tumor cells with EMA (arrow), × 400
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 | Figure 5: (a-d) Axial serial contrast CT brain sections showing no evidence of residual tumor at one-year follow-up
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Five of the six reported cases of EASE [Table 1] including our patient were male and the age ranged from 13 to 45 years and our patient was aged 35 years. The pure subarachnoid location of the tumor in our patient could be explained by the hypothesis proposed by Sato et al., [7] that these tumors develop from ependymal cysts (subarachnoid) which develop as an outpouching from the ventricles, and are derived from ectopic ependymal nests resulting from migration disorders of the germinal matrix. All the five reported cases of extra-axial supratentorial ependymoma were WHO Grade II tumors. Short-term follow-up of 6, 9 and 12 months was reported in three of these five cases with no recurrence after gross total resection. The present patient with a WHO Grade III tumor, had no recurrence at 12 months of follow-up. Longer follow-up will demonstrate the true nature of this tumor. Two of the previous five reported cases [3],[6] received radiation therapy due to their size and rate of progression. In view of the higher grade of the tumor in our patient, adjuvant radiotherapy was given.
All the reported cases of EASEs were lobulated, well-circumscribed with calcification, cystic degeneration, and heterogeneous contrast enhancement. They were all radiologically diagnosed as meningiomas [2],[3],[4],[5],[6] [Table 1]. Both these tumors can be isointense on T1- and T2-weighted images; however, meningiomas have homogenous contrast enhancement and often show the dural tail sign. The present case had homogenous contrast enhancement, but did not have a dural tail sign. None of the reports mention whether they had a dural tail sign. An MR-spectroscopy was not done in our patient. An alanine peak seen in meningiomas and a choline peak seen in ependymomas may help differentiate the two. It was fortuitous that our patient chose to undergo open surgery in spite of the treating physicians suggesting radiosurgery. This underscores the importance of taking great care and making sure that all the radiological findings including dural tail sign and MR-spectroscopy are typical for a meningioma before subjecting a patient to radiosurgery on the basis of radiological findings alone.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1]
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