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|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 2 | Page : 345-348
Pure extra-axial supratentorial anaplastic ependymoma with no cortical attachment: A rare case
Vipin K Gupta1, Isha Kapoor1, Bishan D Radotra2, Debajyoti Chatterjee2
1 Department of Surgery, Government Medical College and Hospital, Chandigarh, Punjab and Haryana, India
2 Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab and Haryana, India
|Date of Web Publication||3-Mar-2016|
Vipin K Gupta
Department of Surgery, Government Medical College and Hospital, Chandigarh, Punjab and Haryana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gupta VK, Kapoor I, Radotra BD, Chatterjee D. Pure extra-axial supratentorial anaplastic ependymoma with no cortical attachment: A rare case. Neurol India 2016;64:345-8
|How to cite this URL:|
Gupta VK, Kapoor I, Radotra BD, Chatterjee D. Pure extra-axial supratentorial anaplastic ependymoma with no cortical attachment: A rare case. Neurol India [serial online] 2016 [cited 2020 Nov 28];64:345-8. Available from: https://www.neurologyindia.com/text.asp?2016/64/2/345/177626
An ependymoma is a glial tumor that arises within or adjacent to the ependymal lining of the ventricular system or the central canal of the spinal cord. Less commonly, it may arise from the brain parenchyma without any continuity with the ventricular system, representing an extraventricular or an ectopic form. Extraventricular ependymomas that are supratentorial in location are rare, and extra-axial supratentorial ependymomas are even rarer, with less than 10 cases described in literature, out of which only 3 were anaplastic ,, and all had some cortical attachment. Herein, we report the first case of a pure extra-axial supratentorial anaplastic ependymoma with no cortical involvement.
A 9-year-old boy presented with seizures and left-sided hemiparesis for the past 1 year. Neurological examination showed Medical Research Council grade 4/5 power in the left upper and lower limbs. Ten months ago, he had presented to the Pediatrics outpatient department (OPD) of the hospital, and a computed tomography (CT) scan of the head was done. It showed a well-defined lobulated extra-axial mass measuring 6.4 × 5.2 cm in the right frontoparietal area with a clear cerebrospinal fluid plane between the tumor and the brain parenchyma [Figure 1]a. He was advised surgery, but the patient's relatives brought him to the neurosurgery department after 10 months when his symptoms progressed. A fresh magnetic resonance imaging (MRI) scan was obtained in which the mass had increased to 9.8 × 7.5 × 8.3 cm in size, pushing the ipsilateral ventricle medially, but without any communication with the latter; it demonstrated hyperintensity on T2-weighted images [Figure 1]b and isointensity on T1-weighted images [Figure 1]c. The lesion was provisionally diagnosed as a meningioma.
|Figure 1: (a) A 10-month-old CT scan showing a lobulated extra-axial mass in the right frontoparietal region. (b) Preoperative axial T2-weighted MRI showing the extra-axial lesion with hyperintensity. (c) Preoperative sagittal T1-weighted MRI|
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The patient underwent a right frontoparietal craniotomy. Despite being highly vascular, the tumor had a good plane of dissection from the surrounding brain parenchyma. There was no cortical attachment or any continuity with the ventricular system [Figure 2]. A gross total resection of the tumor was achieved. Postoperative recovery was uneventful. On microscopic examination, the tumor cells were oval, elongated, and arranged in sheets, and perivascular pseudorosettes were present [Figure 3]a and [Figure 3]b. Increased mitosis was seen in hypercellular areas (6–7/10 hpf). On immunohistochemistry, the tumor cells demonstrated glial fibrillary acidic protein (GFAP) positivity [Figure 3]c. Perinuclear dot-like epithelial membrane antigen (EMA) positivity was present [Figure 3]d. The tumor cells were negative for CD34, synaptophysin, and progesterone receptor. Ki-67 proliferative index was focally high (5%–6%). Based on these features, a diagnosis of extraventricular ependymoma, anaplastic variant (WHO grade III), was made.
|Figure 3: (a) Photomicrograph showing a cellular tumor with prominent perivascular pseudorosette formation (hematoxylin–eosin [HE], ×100). (b) Tumor cells are oval to elongated, with cytoplasmic processes radiating away from the blood vessels (HE, ×200). (c) Faint GFAP positivity in the tumor cells with perivascular accentuation (immunoperoxidase (IP), ×200). (d) Perinuclear dot-like EMA positivity in the tumor cells (IP, ×200)|
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At a follow-up visit after 15 months, the symptoms had completely resolved, and on imaging, there was no residual tumor or recurrence [Figure 4].
|Figure 4: Postoperative MRI (after 15 months), axial (a) and coronal (b) view showing no residual tumor|
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Majority of the ependymomas are infratentorial in location (60%), while the supratentorial ones constitute 40% of the tumors. Supratentorial ependymomas that are extra-axial are very rare, with only a few reported cases in the literature. Although 8.5%–11.5% of all ependymomas are anaplastic, only three cases of anaplastic variants of extra-axial supratentorial ependymomas have been reported.,, All these had varying degrees of cortical involvement; however, ours was the only case in which the tumor was purely extra-axial with no cortical involvement.
Several hypotheses have been put forward to explain the origin of extra-axial ependymomas with no connection to the ventricles. Fukui et al., proposed that such a tumor arises from glial rests in the subarachnoid space to produce an extra-axial mass. Hayashi et al., suggested that the tumor originates around the ventricle, grows and extends extramedullarly, followed by degeneration and necrosis of the ventricular portion of the tumor, leaving an extra-axial ependymoma. According to Lyons et al., grossly nonvisible microscopic cellular tracts exist in development, between the ventricle and extra-axial ependymoma that facilitate tumor extension into the subarachnoid space. These extensions subsequently regress. Vernet et al., postulated that (1) tumors develop from intraparenchymal or subarachnoid ependymal cysts that result from disorders of migration from the germinal matrix; (2) they represent primitive neuroectodermal tumors that have differentiated extensively along the ependymal lineage; and, (3) they might be the result of neoplastic growth within ectopic ependymal cells and are the consequence of a migration error. We propose that in this case, the tumor most probably arose from heterotopic cell residues in the subarachnoid space of the frontoparietal region that eventually transformed into malignant cells.
On the CT, image, an ependymoma as a whole demonstrates moderate-to-intense contrast enhancement, while on MRI, the tumor is isointense or hypointense to white matter on T1-weighted images and heterogeneous or hyperintense on T2-weighted images. Microscopically, perivascular pseudorosettes are commonly present. Immunohistochemically, these tumors are reactive for GFAP and S-100 protein.
The treatment of ependymoma consists of surgical excision, with an estimated 5-year survival rate of 67%–80% for completely resected tumors, compared with an estimated 5-year survival rate of 22%–47% in patients with incompletely resected tumors. Postoperative radiotherapy is usually required in anaplastic cases or when there is incomplete removal. It has been noted that irradiation of the supratentorial compartment and temporal lobes results in a significant decline in the intelligence quotient (IQ) regardless of the dosage level, with each gray (Gy) of exposure having a similar impact on the decline in IQ. In view of the young age of our patient and no cortical or ventricular involvement, radiotherapy was not given, and the child has been kept on a regular follow-up.
Even though extra-axial supratentorial ependymoma is a rare entity, it should be included in the preoperative differential diagnosis of extra-axial lesions. Although there are no recommended guidelines for the management of extra-axial ependymomas, it is advised that gross total resection should be done in such patients. Postoperative radiotherapy and chemotherapy are still controversial. Routine surveillance imaging must be done at frequent intervals so that recurrence, if any, might be dealt with at the earliest.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
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