Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 58, Num. 6, 2010, pp. 966-968

Neurology India, Vol. 58, No. 6, November-December, 2010, pp. 966-968

Letter to Editor

Ganglioneuroblastoma of the conus: A rare and aggressive tumor

Sunil K Singh¹, Chhitij Srivastava¹, BK Ojha¹, Anil Chandra¹, Nuzhat Husain²

¹ Department of Neurosurgery, CSM Medical University, Lucknow - 226 003, India
² Department of Neuropathology, CSM Medical University, Lucknow - 226 003, India
Correspondence Address: Sunil K Singh, Department of Neurosurgery, CSM Medical University, Lucknow - 226 003, India, drsksingh2k@gmail.com

Date of Acceptance: 30-Jul-2010

Code Number: ni10276

PMID: 21150078
DOI: 10.4103/0028-3886.73778

Sir,

The term 'ganglioneuroblastoma' is used for tumors that histologically consist of small round immature tumor cells in all stages of neuronal differentiation with scattered immature ganglion cells. These tumors are grouped under 'primitive neuroectodermal tumors' (PNETs): (1) 'peripheral' or 'pPNET'- those that arise from the sympathetic nervous system and (2) 'central' or 'cPNET' - those that arise within the central nervous system (CNS). Although both may be histologically similar, pPNET and cPNET have different clinical, immunochemical and genetic profiles. ^[1] These tumors have only rarely been found in the CNS. Even rarer is the occurrence of a primary intraspinal ganglioneuroblastoma. Of the reported cases of intramedullary ganglion cell tumors, there was only one case of ganglioneuroblastoma, while all others were cases of gangliogliomas, ganglioneuromas, gangliocytomas, neurocytomas or mixed-type tumors. ^[2],[3] The occurrence of an unusual and aggressive intramedullary ganglioneuroblastoma of the conus in a young girl, which is so far an unreported entity, prompted us to present this case.

A 16-year-old girl presented with a 2-month history of low back ache and a predominantly motor paraparesis without bladder involvement. Magnetic resonance imaging (MRI) showed a large apparently intramedullary inhomogeneously enhancing lesion at D12 level with a few necrotic foci [Figure - 1] and [Figure - 2]. The patient was taken up for surgery, and an anteriorly placed soft suckable mildly vascular exophytic intramedullary tumor was seen. There was no defined tumor-cord interface, and subtotal excision was done. The histology showed differentiating neuroblasts with admixed ganglion cells. The tumor cells were positive for synaptophysin, while some background cells were glial fibrillary acidic protein (GFAP) positive. Thus the final diagnosis was ganglioneuroblastoma [Figure - 3]. The patient returned six weeks later with progressive sensory-motor paraparesis with 0/5 power in the left lower limb. Repeat MRI revealed a large recurrent tumor involving the conus-cauda region [Figure - 4]. There was no other lesion along the whole spine or brain. The patient was re-operated, and again subtotal excision could be done. In view of the aggressive nature of the lesion, the patient was referred for early adjuvant radiotherapy. However, the patient declined further treatment and died 5 months after surgery.

The World Health Organization (2007) recognizes 3 entities among the embryonal tumors of the CNS, namely, the medulloblastomas, the primitive neuroectodermal tumors (PNETs) and the atypical rhabdoid/ teratoid tumors. All three entities correspond to malignant grade IV tumors histologically. The PNETs include the CNS neuroblastoma, CNS ganglioneuroblastoma (ICD-O code 9490/3), medulloepithelioma and ependymoblastoma. ^[4] CNS neuroblastomas and ganglioneuroblastomas, which were earlier classified into both neuronal tumors and embryonal tumors by WHO, ^[2] are now classified only under embryonal tumors. Cases of PNET have been increasingly reported in recent years since the term was first introduced by Hart and Earle in 1973, but there are still very few reports of PNET originating in the spinal cord. To date, only 18 cases of primary intraspinal PNETs have been reported in the literature. ^[5] Central PNETs most commonly occur in the cerebellum (medulloblastomas) but can arise in the pineal gland, cerebrum, spinal cord and brainstem. These frequently metastasize via the CSF pathways to the spinal and cranial subarachnoid spaces and are highly malignant both histologically and clinically. ^[5] The prognosis for patients with these tumors is relatively unfavorable, and the 5-year survival rate for neuroblastomas after surgical treatment is around 30%; a high risk of recurrence and meningeal dissemination has also been reported. ^[6],[7]

Ours is the first case of an intramedullary ganglioneuroblastoma occurring in the conus region. Our illustrative case is significant because of the fact that most conus lesions are low-grade ependymomas or astrocytomas. Our patient had neurological and radiological tumor progression within six weeks after surgery, proving the aggressive and malignant nature of the tumor. This also justifies the WHO grading as a malignant grade IV tumor. The tumor was radiologically similar to the common conus ependymoma; and except for the short clinical history, there was no other specific difference. Thus neuroblastic embryonal tumors should be kept in mind in the differential diagnosis of intramedullary conus tumors.

References

1.	Ozdemir N, Usta G, Minoglu M, Erbay AM, Bezircioglu H, Tunakan M. primary primitive neuroectodermal tumor of the extradural space. J Neurosurgery Pediatrics 2008;2:215-21.  Back to cited text no. 1
2.	Kikuchi K, Saito M. Ganglion- cell tumor of the filum terminale: Immunohistochemical characterization. Tohoku J Exp Med 1999;188:245-56.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.	Tripathy LN, Forster DM, Timperley WR. Ganglioneuroblastoma of the cauda equina. Br J Neurosurg 2000;14:264-6.  Back to cited text no. 3  [PUBMED]
4.	Kleihues P. Pathology and genetics of tumours of the nervous system. In: Kleihues P, editor. World Health Organization Classifi cation of Tumours. Lyons: IARC Press; 2000. p. 141-4.  Back to cited text no. 4
5.	Virani MJ, Jain S. Primary Intraspinal Primitive Neuroectodermal Tumor (PNET): A Rare Occurrence. Neurol India 2002;50:75-80.  Back to cited text no. 5  [PUBMED]
6.	Berger MS, Edwards MS, Wara WM, Levin WA, Wilson CB. Primary cerebral neuroblastoma. Long-term follow-up, review, and therapeutic guidelines. J Neurosurg 1983;59:418-23.  Back to cited text no. 6
7.	Horten BC, Rubinstein LJ. Primary cerebral neuroblastoma. A clinicopathological study of 35 cases. Brain 1976;99:735-56.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]

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