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REVIEW ARTICLE |
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| Year : 2020 | Volume
: 15
| Issue : 3 | Page : 183-189 |
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Holocord tanycytic ependymoma: An interesting case with unusual presentation, challenging histological diagnosis, and single-staged complete tumor resection
Suresh K Sankhla, Ghulam M Khan
Department of Neurosurgery, Global Hospital, Mumbai, India
| Date of Submission | 17-Aug-2019 |
| Date of Decision | 04-Nov-2019 |
| Date of Acceptance | 29-Mar-2020 |
| Date of Web Publication | 06-Nov-2020 |
Correspondence Address:
Dr. Suresh K Sankhla
A-503, Chaitanya Towers, A. M. Marg, Prabhadevi, Mumbai, Maharashtra.
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jpn.JPN_100_19
 Abstract | | |
An interesting case of intramedullary holocord cystic tumor in an 11-year old boy is reported, who presented with unusual clinical manifestations and radiological features. Gross total resection of the tumor was performed in a single-staged surgery. A rare combination of unusual presentation, uncommon histopathological findings, and challenges in the selection of surgical options were discussed with a detailed review of the literature.
Keywords: Ependymoma, holocord, intramedullary, tanycytic
How to cite this article:
Sankhla SK, Khan GM. Holocord tanycytic ependymoma: An interesting case with unusual presentation, challenging histological diagnosis, and single-staged complete tumor resection. J Pediatr Neurosci 2020;15:183-9 |
How to cite this URL:
Sankhla SK, Khan GM. Holocord tanycytic ependymoma: An interesting case with unusual presentation, challenging histological diagnosis, and single-staged complete tumor resection. J Pediatr Neurosci [serial online] 2020 [cited 2020 Nov 24];15:183-9. Available from: https://www.pediatricneurosciences.com/text.asp?2020/15/3/183/300029 |
| Introduction | |  |
Spinal intramedullary tumors extending along the entire length of the spinal cord, termed as “holocord” tumors, are uncommon.[1] Generally, gliomas, particularly the low-grade astrocytomas, are the most common intramedullary tumors in children that involve multiple segments of the spinal cord. Holocord ependymomas in children are rare, and only seven cases have been reported till date.[2],[3],[4],[5],[6] The histopathologic diagnosis of the tumor in our patient was “tanycytic ependymoma,” which is a rare variant of ependymoma with histological features not typical of an ependymoma and closely resembling an astrocytoma or schwannoma. The surgical management of holocord tumors is challenging because of the lack of well-described surgical techniques and strategies. Before this report, there have been only two cases described in the literature in whom complete removal of the holocord ependymoma was performed in a single stage.
| Case Report | | |
An 11-year-old boy presented with progressive long-standing scoliosis and limping gait without pain or bladder–bowel involvement. On examination, he had normal cranial nerve function and normal power in upper extremities with diminished tendon reflexes. The power in his left ankle was grade 3+ with brisk reflexes, bilateral extensor plantar responses, and impaired posterior column sensations in the lower limbs. He had a severe degree of dorsal scoliosis to the left side [Figure 1]. His magnetic resonance imaging (MRI) scan showed a large hypo- and hyperintense intramedullary lesion from C1 to D12 regions on T1- and T2-weighted sequences, respectively, with heterogenous contrast enhancement [Figure 2]. There was a marked dilatation of the spinal cord and presence of a large cyst with non-enhancing margins at the rostral pole of the tumor, extending from C3 to the medulla. | Figure 1: Clinical images (A and B) and X-ray spine (C) of an 11-year-old boy showing scoliosis of the dorsal spine
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 | Figure 2: MRI showing an intramedullary hypo-(T1) and hyperintense (T2) tumor in the cervical cord up to C4 level and a cyst extending from C3 to the medulla oblongata on T2-weighted sagittal images (A); irregularly contrast-enhancing tumor with dilatation of the cervical and dorsal spinal cord on sagittal (B) and axial images (C and D); T2-weighted sagittal (E) and axial (F) images showing tumor extension up to D12 level
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During surgery, the intramedullary tumor was localized by intraoperative ultrasonography (iUSG) and was resected safely and completely using ultrasonic aspirator (CUSA). A midline myelotomy, first performed at C5-C6 region as the tumor mass was approaching closest to the cord surface on iUSG, was subsequently extended rostrally up to C3-C4 level to identify tumor–cyst interface. The tumor was grayish in color, soft in consistency, minimally vascular, and well-delineated from the surrounding normal cord parenchyma. A good plane of cleavage could be identified to dissect and remove the tumor with the help of the aspirator and microsurgical techniques. The polar cyst was drained completely. The myelotomy was then extended caudally, step by step, and the tumor removal was continued downward up to D12 level using the same tumor-cord plane. Complete tumor removal and hemostasis were confirmed on the iUSG. No significant disturbance was observed on intraoperative monitoring of the somatosensory and motor-evoked potentials (MEPs) during tumor removal. The midline myelotomy from C4-D11 was closed with interrupted 8.0 Prolene suture, and the dura was approximated with a continuous 6.0 proline suture. Bony reconstruction of the posterior spinal canal was achieved by performing laminoplasty from C4-D11. The patient remained neurologically unchanged postoperatively and was ambulated in a Taylor’s brace after 2 weeks. Postoperative MRI scan revealed a near-total removal of the tumor [Figure 3]. The histopathology of the tumor was suggestive of tanycytic ependymoma (World Health Organization [WHO] Grade II) [Figure 4]. At follow-up after 6 months, the child was found to have improved in his left foot weakness and gait with stable dorsal spinal deformity. | Figure 3: Postoperative magnetic resonance T1-weighted (A–C) and T2-weighted sagittal images (D) showing gross total tumor resection
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 | Figure 4: Histological sections (A and B) showing vessels along with radiating slender or plum cells with vesicular nuclei and distinctly light and dark regions of chromatin (similar to ependymoma), in conjunction with marked fibrillarity and microcytic changes with scattered Rosenthal bodies (similar to astrocytoma)
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| Discussion | | |
Our case highlights few interesting issues in the management of holocord spinal tumors in children. First, astrocytoma is a more common intramedullary spinal tumor in pediatric population than ependymoma, which is more frequently found in adults at the lower dorsal cord and conus, and in cervical spine.[7] Ependymoma presenting as a holocord tumor in children is extremely rare. Following the first case report by Cushing,[8] in 1927, only seven more cases of holocord ependymoma have been reported in the literature till date.[2],[3],[4],[5],[6]
Ependymomas are nonencapsulated tumors of glial origin and are mostly benign and slow growing in nature. Patients usually present with prolonged symptoms such as neck pain, quadriparesis, and bladder–bowel dysfunction.[6] However, clinical presentations with unusual or seemingly unrelated symptomatology are also well recognized. Aghakhani et al.,[9] in 2008, described consecutive 82 patients with cervical ependymoma, 10 of which were without any significant neurological deficit. Early surgery is believed to prevent further neurological deterioration, and possibly plays an important role in improving neurological functions. However, subtle- and slow-progressing clinical features often tend to mislead or delay the diagnosis and treatment.[6] In our patient, the symptoms were initially attributed to his spinal deformity, and as a result, the diagnosis and surgical intervention were delayed considerably.
The management of holocord spinal tumors remains a debatable subject as optimal treatment has not been described in the literature. Owing to the unavailability of specific surgical strategies and techniques, the holocord tumors are usually treated with the same surgical principles as used in focal intramedullary tumors. It is not clear whether radical removal of the tumor should always be attempted or only symptomatic part of the tumor should be addressed. Surgical management of the associated polar cysts, residual smaller intrinsic lesions in the medulla, and exophytic tumor extensions is also controversial. Confusion exists regarding the surgical approaches, especially single-stage versus staged surgery. The role of adjunctive therapy in the management of holocord ependymomas has also not been defined clearly. There are no clear guidelines for the use of laminectomy or laminoplasty in these cases.
There is clear evidence that postoperative outcome in cases of intramedullary spinal tumors primarily depends on the functional status of patients at the time of surgery and the extent of tumor removal.[6],[9] As documented in our case and those of other authors,[6] ependymomas generally have a good plane of cleavage from the surrounding neural tissue and are therefore amenable to gross total removal without any additional neurological deficit. Peker et al.[10] analyzed the outcome with various factors such as the tumor length and width, cyst dimensions, and the presence of cord edema, and found that the wider tumor diameter, and not the tumor length, was associated with poor postoperative outcome. Staging of surgery was not evaluated in their study. Tobias et al.[11] described 13 cases of long-segment intramedullary tumors, which were excised in single stage or staged manner (in two cases), and reported that the modified McCormick score (MMS) had worsened in two (15%), improved in three (23%), and remained stable in seven (54%) patients. Gunes and Ozdemir,[5] in 2012, reported successful removal of a holocord ependymoma in a 19-year-old girl in two stages and recommended this approach for total removal of the long-segment intramedullary tumors. Bhaisora et al.,[6] in 2015, published an elegant surgical report of a holocord ependymoma removal in a 15-year-old girl, who was the only second case published in the literature in whom gross total tumor removal was achieved in a single-stage surgery. The authors further emphasized that the postoperative outcome in these patients mainly depends on patient’s preoperative MMC grade, plane of tumor-cord cleavage, tumor suckability, and the availability of equipment to facilitate fast surgery (operating microscope, high-speed drill, ultrasonic aspirator, and fluid warmer), and good neuro-anesthesia support.
On the basis of our own experience and a review of the literature, we agree with the other authors that it is safer and feasible to remove pediatric holocord tumors, particularly ependymomas, totally in a single-stage surgery using microsurgical techniques and modern technology. iUSG is found to be specific in distinguishing the tumor type, margins, and the presence or absence of associated cysts.[12] It greatly facilitates the selection of respective sites for the placement of a myelotomy and guides safe tumor removal in a surgical field where anatomical landmarks are limited and the margin for error is minimal. Completeness of the tumor removal and accumulation of blood in the tumor cavity can also be evaluated precisely on iUSG. The role of ultrasonic aspirator is invaluable in surgery for intramedullary tumors.[13] This technique apparently enables gross total removal of astrocytomas and ependymomas of the spinal cord with essentially no retraction of adjacent neural tissue. Intraoperative neuromonitoring, particularly monitoring of MEPs, during surgery is extremely helpful.[14] The impairment of the functional integrity of the motor pathways can be detected before permanent deficits occur. In our case, the occurrence of transient slowing of MEPs, a few times during tumor dissection, followed by prompt and complete recovery of the evoked potentials on cessation of the tumor maneuvering, averted major postoperative deficit.
Longer duration of anesthesia, however, remains a major concern, especially in the surgery of younger patients. Meticulous management of blood loss, body temperature alterations, and fluid and electrolyte imbalance is crucial to avoid unnecessary morbidity. A neurosurgical team specialized in pediatric spine surgery, and a good support from the experienced neuro-anesthesia and neuro-intensive colleagues are extremely important for successful outcome. The use of laminoplasty or laminectomy depends primarily on surgeon’s expertise and preference. The advantages of laminoplasty over laminectomy in growing children have been documented extensively in the literature.[6] We preferred to do laminoplasty in our patient because of his young age and progressively increasing scoliosis.
Lastly, the other interesting feature in our case was its unusual histopathological diagnosis. First described by Friede and Pollak,[15] in 1978, tanycytic ependymoma is a rare form of ependymoma, a WHO grade II tumor with histological characteristics distinct from the typical features of commonly encountered ependymomas. In these lesions, the classic ependymal rosettes and perivascular pseudorosettes are replaced by more fibrillar cells. The cellular appearance and arrangement may mimic other lesions such as schwannoma and astrocytoma, which makes the diagnosis challenging.
One distinguishing feature from a schwannoma is that tanycytic ependymoma cells are more uniform, and their nuclei are more oval compared with those of schwannoma cells. Although the long processes from tanycytic ependymoma cells resemble those of pilocytic astrocytoma, findings such as the absence of Rosenthal fibers, presence of large ovoid nuclei, tight perivascular packing of the cells, and isomorphic cellular appearance can help differentiate it from astrocytoma.[16],[17] In difficult situations, the neuropathologist should resort to immunohistochemical and ultrastructural features to characterize the tumor type. Tanycytic ependymoma stains positive for glial fibrillary acidic protein (GFAP) and vimentin but rarely stains S-100 to differentiate it from schwannoma, which is S-100 positive and GFAP negative. Although, pilocytic astrocytoma is GFAP positive, it almost never stains for vimentin, which helps to discriminate it from tanycytic ependymoma.[18]
Like classic ependymomas, tanycytic ependymomas are also slow-growing tumors and their behavioral pattern is essentially benign. Because of the rarity of this tumor, it is difficult to find adequate information in the literature regarding the long-term clinical outcome and the management of residual or recurrent tumors. Until more and larger multicentric studies are published with improved clarity on its natural history and optimal surgical strategies, the management of residual tanycytic ependymomas (observation, surgery or adjuvant therapy) continues to be based on the clinical condition of the patient, similar to classic ependymomas.[7],[9],[11],[18]
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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