[A clinicopathological study of central neurocytoma]

In 1982, Hassoun et al. reported two cases of differentiated neuroblastoma with the clinical and light microscopic appearance of intraventricular oligodendroglioma and gave a name of "central neurocytoma" to this tumor. Jerdan et al. (1983) called the similar tumor as "differentiated cerebral neuroblastoma in adults". As the tumor can be diagnosed only by ultrastructural study, the established cases so far reported are very rare. In this paper we present five cases identical to those presented by Hassoun et al. and clarify the essential nature of this new category of brain tumors. All of our cases of central neurocytoma occurred in the lateral ventricles of young adults. Clinically there was no evidence of leptomeningeal or ventricular dissemination of tumor cells. After subtotal resection of the tumor and 6000 rads of whole brain irradiation, the tumor mass disappeared and no evidence for recurrence of the tumor was noted on CT scan. All cases showed almost the same histology. The tumor cells contained a small round and/or oval nucleus, and had eosinophilic thin delicate cytoplasmic processes. There were no Homer Wright rosette, but were anuclear spaces consisting of fine fibrillar structures, like so called "broad rosettes" or "large rosettes". Capillary mesh was found among the tumor cells, but there was no endothelial proliferation. The tumor cells were monotonous, lacking pleomorphism, mitotic figures, and necrotic foci. Calcifications were observed in two cases. In the areas where the tumor cells arranged loosely, cytoplasms became clear, showing perinuclear halo, like those of oligodendrogliomas. Immunohistochemical examination showed GFAP and vimentin positive cells were all reactive astrocytes around capillaries and near calcifications. No tumor cells contained GFAP and vimentin. The tumor cells were also negative for neurofilament both of 70 KD and 200 KD. NSE was more or less positive for tumor cell cytoplasm as well as fine fibrils. Anti-Leu7 antibodies stained only fine cytoplasmic processes, but not cytoplasm. Some reactive astrocytes were stained with anti-Leu7 antibodies. Electron microscopic examination showed nuclei of the tumor cells were roughly round or oval without nuclear indentations and contained finely dispersed nuclear chromatin. In the cytoplasm, there were numerous free ribosomes, mitochondria, Golgi apparatus and electron dense various-shaped granules. Microtubules were found in the periphery of the cells, but filamentous structures were not identified.(ABSTRACT TRUNCATED AT 400 WORDS)