BMJ Case Rep: first published as 10.1136/bcr-2019-231626 on 16 September 2019. Downloaded from Images in… Central neurocytoma in the posterior fossa Pranav Rai, Raghavendra Nayak, Debish Anand, Girish Menon

Neurosurgery, Kasturba Medical Description College Manipal, Manipal Central neurocytomas (CNs) are rare, benign Academy of Higher Education neoplasms arising from a neuronal lineage and (MAHE), Manipal, Karnataka, account for 0.1%–0.5% of all central nervous India system tumours. Typical location of CNs is the lateral ventricle touching the foramen of Correspondence to 1 Dr Raghavendra Nayak, Munro. Occurrence of the tumours in the poste- drnayakneuro@​ ​gmail.com​ rior fossa is extremely rare; till now only seven cases (table 1) have been reported to the best of Figure 2 H&E staining showing (A) isomorphic 2 Accepted 21 August 2019 our knowledge. cells with clear cytoplasm, speckled chromatin and An 8-year-old girl was presented to us with fibrillar matrix. (B) Synaptophysin positivity on early morning headache and blurring of vision immunohistochemical study. for 1 month and gait instability for 15 days. These symptoms were gradually progressive. Since 3 The patient underwent a midline suboccipital days, she started having intractable nausea and craniotomy and complete excision of the tumour. vomiting. Neurological examinations showed Histopathology showed the isomorphic cells with mild papilledema and bilateral sixth nerve paresis, clear cytoplasm, speckled chromatin and fibrillar indicating raised intracranial pressure. She had matrix, suggesting oligodendroglioma or ependy- an ataxic gait. CT scan was showing an ill-de- moma. But, immunohistochemical study was posi- fined, lobulated, heterogeneously enhancing and tive for synaptophysin and neuron-specific enolase hypodense intraventricular lesion arising from and negative for glial fibrillar acidic protein, the floor of the fourth ventricle. There was no suggesting the CN. Histological features were atyp- evidence of calcification or haemorrhage within ical, and the proliferation marker (Ki-67) was 1 the lesion. MRI demonstrated an inhomogeneous, (figure 2). heterogeneously enhancing vermian mass with few CNs were first described by Hassoun et al3 in cystic areas with supratentorial obstructive hydro- 1982. They are considered as low-grade tumours cephalus. Mass was hypointense on T1-weighted (WHO grade II), with an 89% 5-year survival.2 sequences and hyperintense in T2-weighted They are usually arising from the lateral ventricle, sequences (figure 1). Our differential diagnosis rarely the third ventricle. It usually affects young http://casereports.bmj.com/ was medulloblastoma, ependymoma or atypical adults in their 30s (average age is 30 years).1 teratoid rhabdoid tumour. Although they are considered essentially benign in many cases, there are some reported cases of atyp- ical neurocytomas with a higher proliferation rate.4 CNs are described having an origin from grey matter nuclei in the septum pellucidum. This thought resembles the hypothesis given by Hassoun et al4 that the possibility of having CNs outside the lateral or third ventricular system is almost nil. So, on September 29, 2021 by guest. Protected copyright. it is exceptionally rare to have CNs in the fourth ventricle or cerebellum. Surgical excision has been considered as best in the management of these tumours. Reduction in proliferation rate following radiotherapy has been reported in some studies.5 For this reason, postop- erative radiation can be considered in cases with incomplete resection of tumours or in tumours with higher proliferation rate.2 Figure 1 CT scan: (A, B) an ill-defined lobulated Our case was unique because of two reasons. heterogeneously enhancing hypodense intraventricular One, it was a CN of the fourth ventricle; two, © BMJ Publishing Group Limited 2019. No commercial lesion arising from the floor of the fourth ventricle. No our patient was a child of 8 years, as CNs are re-use. See rights and evidence of calcification or haemorrhage within the uncommon in the paediatric age group. So, CNs permissions. Published by BMJ. lesion. MRI: a fourth ventricular mass which was (C) should be considered in the differential diag- hypointense on T1-weighted image, (D) hyperintense nosis of fourth ventricle mass even in the paedi- To cite: Rai P, Nayak R, Anand D, et al. BMJ Case on T2-weighted image, (E) hyperintense on fluid- atric age group although they are extremely rare. Rep 2019;12:e231626. attenuated inversion recovery sequence, and (F) Showing IHC is essential to differentiate CNs from other doi:10.1136/bcr-2019- heterogeneous enhancement on giving gadolinium tumours like oligodendrogliomas and ependy- 231626 contrast. momas. Surgical excision is the primary modality

Rai P, et al. BMJ Case Rep 2019;12:e231626. doi:10.1136/bcr-2019-231626 1 BMJ Case Rep: first published as 10.1136/bcr-2019-231626 on 16 September 2019. Downloaded from Images in…

Table 1 Review of literature Presenting Study Age/sex complaint Imaging Surgery Histopathology Warmuth-Metz et al4 17/male Ataxia, blurring of vision Homogenous enhancement, Partial resection+ Atypical. calcification, hydrocephalus radiotherapy Ki-67: 10%. Hsu et al1 35/male Headache, blurring of vision Heterogeneously Gross total resection Atypical. enhancement, cystic Ki-67: 2%–10%. Cook et al6 58/female Headache, ataxia, Heterogeneous Partial resection+ Typical nystagmus enhancement, calcification radiotherapy Ki-67:<1% Gallina et al7 68/female Headache, vomiting, Heterogeneously Gross total resection Typical comma enhancement, Ki-67: 1% calcification, haemorrhage Cultrera et al8 28/male Diplopia, gait disturbances Homogeneous enhancement Gross total resection Atypical. Ki-67: 6% Jain et al9 7/male Headache, vomiting Heterogeneous Gross total resection + Atypical. enhancement, haemorrhage radiotherapy Ki-67: 10%–20% Cystic Richardson et al2 70/female Nausea and vomiting, Heterogeneous Near total excision Atypical. vertigo, altered taste enhancement Ki-67: 5%–7% of treatment. A systemic review of the literature has been done Provenance and peer review Not commissioned; externally peer reviewed. and described in table 1. References Learning points 1 Hsu PW, Hsieh TC, Chang CN, et al. Fourth ventricle central neurocytoma: case report. Neurosurgery 2002;50:1365–7. ►► Central neurocytoma should be considered in the differential 2 Richardson AM, Armstrong VL, Gernsback JE, et al. Central neurocytoma: rare diagnosis of posterior fossa tumours even in the paediatric presentation in fourth ventricle and review of literature. World Neurosurg age group. 2019;123:357–61. 3 Hassoun J, Gambarelli D, Grisoli F, et al. Central neurocytoma. Acta Neuropathol ►► Immunohistochemistry plays an important role in 1982;56:151–6. differentiating from other similar looking tumours on 4 Warmuth-Metz M, Klein R, Sörensen N, et al. Central neurocytoma of the fourth microscope like ependymoma and oligodendroglia. ventricle. Case report. J Neurosurg 1999;91:506–9. ►► Surgical excision is the primary modality of treatment for 5 Fujimaki T, Matsuno A, Sasaki T, et al. Proliferative activity of central neurocytoma: measurement of tumor volume doubling time, MIB-1 staining index and central neurocytoma. bromodeoxyuridine labeling index. J Neurooncol 1997;32:103–9. 6 Cook DJ, Christie SD, Macaulay RJ, et al. Fourth ventricular neurocytoma: case report http://casereports.bmj.com/ and review of the literature. Can J Neurol Sci 2004;31:558–64. Contributors PR prepared the manuscript. RN designed and drafted the work. DA 7 Gallina P, Mouchaty H, Buccoliero AM, et al. Haemorrhagic central neurocytoma of the collected and analysed the data. GM approved the final version of the work. fourth ventricle. Acta Neurochir 2005;147:1193–4. Funding The authors have not declared a specific grant for this research from any 8 Cultrera F, Giuffrida M, Guiducci G, et al. Central neurocytoma of the fourth ventricle. funding agency in the public, commercial or not-for-profit sectors. Case history. J Neurosurg Sci 2005;49:125. Competing interests None declared. 9 Jain D, Roy S, Chopra S. Atypical central neurocytoma of fourth ventricle with hemorrhagic complication during surgery in a child. Clin Neurol Neurosurg Patient consent for publication Parental/guardian consent obtained. 2012;114:182–4.

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2 Rai P, et al. BMJ Case Rep 2019;12:e231626. doi:10.1136/bcr-2019-231626