Intraventricular Neurocytoma: A Clinical and Pathological Study of Three Cases and Review of the Literature

Abstract

Three patients with a recently described tumor of neuronal origin, intraventricular neurocytoma, are presented. These tumors occur as intraventricular lesions in young patients, and the prognosis after surgical treatment is favorable. The initial pathological diagnosis of intraventricular neurocytoma may be difficult because of the striking resemblance of these tumors to oligodendroglioma and, to a lesser extent, ependymoma on light microscopic examination. Despite the use of wide-ranging panels of monoclonal antibodies, previous authors have not found any characteristic immunohistochemical staining patterns, but in our three patients, the use of synaptophysin, glial fibrillary acidic protein, and Leu-7 demonstrated staining patterns that may be useful in the diagnosis of this tumor. The monoclonal antibody Ki-67 was used to stain one tumor and showed a low cell proliferation rate. We have reviewed the clinical, radiological, and pathological features of these 3 patients and 17 previously described patients in an attempt to determine the important diagnostic features of intraventricular neurocytoma. Intraventricular neurocytoma should be considered in any young patient with symptoms of raised intracranial pressure and radiological evidence of an intraventricular lesion. Pathological diagnosis requires the use of electron microscopy to show features of neuronal differentiation; however, immunohistochemical demonstration of a neuronal phenotype is also a useful adjunct to diagnosis. Failure to use specialized techniques for pathological diagnosis will lead to misdiagnosis of these lesions as oligodendrogliomas, as was the initial diagnosis in 2 of our patients before review.

MR Appearance of Central Neurocytoma

“…Central neurocytoma exhibits immunoreactivity for neuron-specific enolase and synaptophysin, indicating neuronal differentiation. Ultrastructurally, the tumor contains synaptic vesicles, neuritic processes and neurosecretory granules (1,8,(12)(13)(14)18). The tumors are found almost exclusively in the anterior portion of the lateral ventricle, invariably producing an asymmetric hydrocephalus caused by obstruction of the foramen of Monro.…”

“…Common presenting symptoms and signs are those related to increased intracranial pressure including headache, nausea, vomiting, blurred vision, dizziness, memory loss, papillo-edema, and rarely paresis (1,13,14,16). Although 2 cases of malignant variants characterized by an increased mitotic activity, vascular endothelial proliferation, and tumor necrosis, and 3 cases of local tumor recurrences have been recently reported (25), most central neurocytomas have been regarded as benign lesions with a favorable prognosis (1.…”

“…To our knowledge, CT findings of approximately 40 cases of central neurocytoma have been reported (1,3,6,8,9,1617,19,20,24). MR imaging findings, however, have been described in relatively few reports (3,6,17,19,20,24).…”

“…Central neurocytoma is a recently described, rare primary brain tumor of neuronal origin, which is characterized by predominant occurrence in the young adults, exclusive lateral ventricular location, and oligodendroglioma-like histology (1,8,(12)(13)(14)17). Without ultrastructural and immunohistochemical studies, it is difficult to make the correct diagnosis of central neurocytoma, because light microscopic findings of the neurocytoma are quite similar to those of oligodendroglioma or ependymoma (1,8,12,14,18).…”

“…Without ultrastructural and immunohistochemical studies, it is difficult to make the correct diagnosis of central neurocytoma, because light microscopic findings of the neurocytoma are quite similar to those of oligodendroglioma or ependymoma (1,8,12,14,18).…”