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Neurology India, Vol. 51, No. 2, April-June, 2003, pp. 274-276 Short Report Liponeurocytoma of the cerebellum - A case report R. Kachhara, R. N. Bhattacharya, S. Nair, V. V. Radhakrishnan* Departments of Neurosurgery and *Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India. V. V. Radhakrishnan Accepted on 11.04.2002. Code Number: ni03087 ABSTRACT We report the characteristic neuropathological features of a rare case of cerebellar liponeurocytoma in a 62-year-old female. The tumor has a low proliferative potential and carries a favorable prognosis. Key Words: Lipoglioneurocytoma, Cerebellum. INTRODUCTION Cerebellar liponeurocytoma is a rare neoplasm showing neuronal, glial and focal lipomatous differentiation. Only 15 cases have been published in the literature and interestingly all these cases have occurred in the cerebellum. We describe the characteristic histopathological features of a case of cerebellar lipoglioneurocytoma. CASE REPORT A 62-year-old woman presented with unsteadiness of gait and urinary incontinence of 3 months duration. She did not have any features suggestive of raised intracranial pressure. On examination she had bilateral papilloedema and right-sided cerebellar signs. The rest of the neurological examination was normal. A computed tomography (CT) scan revealed an ill-defined isodense mass in the right cerebellar hemisphere, producing compression of the fourth ventricle and obstructive hydrocephalus. There were cystic areas and also areas of calcification within the tumor. There was a mild contrast enhancement. Magnetic resonance imaging (MRI) scan showed an ill-defined isointense mass in the right cerebellar hemisphere with focal hypointensities within it. The fourth ventricle was displaced to the left side (Figure 1). The tumor was extending into the spinal canal up to C2. There were linear streaks of hyperintensity within the tumor mass. On T2-weighted images, the mass was hyperintense and on contrast administration, there was minimal enhancement. The patient underwent a right suboccipital craniectomy and resection of the arch of the atlas and gross total excision of the tumor. The tumor was seen on the surface like an exophytic mass. It was involving the whole of the right cerebellar neocortex, extending to the right cerebellopontine angle, midline up to falx cerebelli and inferiorly to the spinal canal up to the C2 vertebra. The tumor was grayish white with variable consistency. There was a good plane of cleavage with the normal cerebellum. Her postoperative period was uneventful. Following surgery, she improved in her ataxia. The hemotoxyline and eosin-stained paraffin sections showed a moderately cellular tumor showing stellate-shaped astrocytic cells which were loosely textured and supported a glial fibrillary matrix, isomorphic cells containing vesicular nuclei and clear cytoplasm resembling oligodendrocytes, and discrete and compact zones of lobulated masses of mature adipocytes (Figure 2). Transition zones between the cerebellar parenchyma and the tumor could be easily demonstrated in the sections. Characteristic foamy, xanthomatous cells were not seen. Necrosis, mitotic figures and microvascular proliferation were conspicuous by their absence. The GFAP positivity was recorded in astrocytic component and isomorphic cells resembling oligodendroglial cells gave positive immunostaining for synaptophysin. DISCUSSION In 1978, Bechtel et al3 first described a 44-year-old man with an unusual cerebellar tumor which was composed of mature adipose tissue, medullomyomatous, astrocytomous, oligodendromatous and ependymatous areas. Less than 20 cases have been reported in the literature.1,2 Several synonyms-neurocytomallipoma (neurolipocytoma),4 medullocytoma,5 lipomatous glioneurocytoma,6 lipidized mature neuroectodermal tumor of the cerebellum7- have been proposed so as to emphasize its resemblance to central neurocytoma. The prognosis of these tumors is quite different from malignant medulloblastoma. In accordance with this, the WHO working group proposed the term "cerebellar liponeurocytoma" rather than lipomedulloblastoma since labeling this tumor as medulloblastoma may lead to unnecessary aggressive adjuvant therapy. Our case illustrates several interesting histopathological features. The unusual aspect of this case was the presence of patchy zones that were virtually indistinguishable from mature adipose tissue and also evidence of divergent neuronal and glial differentiation in the tumor. This was supported by GFAP and synaptophysin immunoreactivity in the glial and neuronal component of the tumor. Accumulation of lipid within the neoplastic cells is relatively uncommon in tumors of the central nervous system and if present, it usually shows a microvesicular pattern. Microvesicular deposition of lipid may be sometimes observed in malignant tumors such as glioblastoma multiforme. Microvesicular lipid deposition is also seen in benign tumors such as Antoni - B areas in schwannomas, hemangioblastomas, and meningiomas. Macrovesicular accumulation of lipids is distinctly unusual. This pattern of fat accumulation is characteristic of lipomas and liposarcomas and has been reported for meningiomas, astrocytomas and tumors of neuronal derivation. The pathogenesis of lipid accumulation in these tumors is uncertain but has been ascribed to a variety of mechanisms including metaplasia, divergent differentiation and endocytosis of external lipids. 1 Liponeurocytoma of the cerebellum classically manifests between the fourth and sixth decades and the age of the patient ranges between 36 - 67 years (mean 51 years). This is in strong contrast with the age distribution of medulloblastoma, which commonly occurs in the pediatric age group. Similarly, the age distribution differs from that of central neurocytoma, which occurs in a younger age. All the 15 tumors reported in the literature arose in the cerebellar hemisphere, some from the vermis and 2 cases presented as an exophytic mass in the cerebellopontine angle. Our case showed well-differentiated neuronal and glial component as was focal lipomatous differentiation. The neuronal and glial components were easily demonstrated with immunohistochemical staining for GFAP and synaptophysin and thus, we wish to label this tumor as lipoglioneurocytoma. The absence of mitotic activity, necrosis and endothelial proliferation point towards the low proliferative nature of these tumors and favorable prognosis. However, additional reports, more information on molecular genetics and continuous follow-up monitoring of these unusual lipomatous neuroectodermal will provide more information regarding the clinical behavior. ACKNOWLEDGEMENTS The authors wish to thank The Director, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India, for the kind permission to publish this report. REFERENCES 1. Kleihues P, Cavenee WK. Cerebellar liponeurocytoma. In: Pathology and Genetics of Tumours of Central Nervous System. Lyons, France: IAPC Press; 2000. Chapter 6. pp. 110-1.
Copyright 2003 - Neurology India. Also available online at http://www.neurologyindia.com The following images related to this document are available:Photo images[ni03087f1.jpg] [ni03087f2.jpg] |
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