So-called malignant and extra-ventricular neurocytomas: reality or wrong diagnosis? A critical review about two overdiagnosed cases

Central neurocytoma (CN) is described as a rare intra-ventricular benign ne uronal tumor of the brain. Two primary tumors first diagnosed as malignant and extra-ventricular neurocytomas are reported here. Histologically, the t umor of the first patient, a forty-one-year-old man, consisted of monotonou s cells with round nuclei, but no fibrillar background. The second tumor, i n a nineteen-year-old girl, showed areas of moderately pleomorphic round ce lls, with numerous rosettes and ganglion cell differentiation, in an abunda nt fibrillary network. Both presented calcifications. Mitoses were more fre quent in recurrences and spinal locations than in the primaries. All tumors stained strongly for synaptophysin, and GFAP was partly positive in the fi rst case only. Patients received post-surgical radiotherapy and were still alive eight and six years, respectively, after initial surgery. The interpretation of atypical cases, such as ours is not easy: the diagnos es finally retained were oligodendroglioma in the first case and ganglioneu roblastoma in the second case. Furthermore, neurocytomas atypical either by their unusual topographical or histological presentation or by their poor prognosis, have been frequently entitled in this way on synaptophysin posit ivity. So, we were prompted to reassess the entity of CN, seventeen years a fter the first description, to re-appreciate the reality of anatomo-clinica l variants and to discuss the value of synaptophysin positivity in these tu mors. In conclusion, it seems preferable to individualize true classical CN , which has a favorable outcome, from so-called extra-ventricular, atypical and anaplastic, clinically malignant neurocytomas for which complementary treatment is required.