Central neurocytoma: a novel appraisal of a polymorphic pathology. Our experience and a review of the literature.

Central neurocytoma should be considered in the differential diagnosis of intraventricular tumours. The records of 20 patients operated on between 1975 and 2000 for central neurocytoma were retrospectively reviewed, and the histological gradings and clinical outcomes were compared. On the basis of our previous cases, in the latter five of this series, the following therapeutic protocol was adopted. In those cases in which total removal was achieved, no further treatment was given if the MIB-1 index was <4%; vice versa, if it was >4%, a course of conformational radiotherapy was delivered. In subtotally removed cases, radiosurgery with linac was also performed (median dose 20 Gy) as well as conformational radiotherapy whenever there was a recurrence of the lesion (median dose 45 Gy). In cases in which there was only partial cytoreduction, conformational radiotherapy was administered with the adjunct of polychemotherapy if the MIB-1 was >4%. Twenty patients were surgically treated: 11 men and nine women, with an average age of 26 years (range 17 years to 42 years).Total, subtotal and partial removals were achieved in, respectively, ten, three and seven cases. At average follow-up of 7 years, 16 patients had been cured, had significantly improved or were at least stable [Karnofsky performance status score (KPS)] >70 or more)]. On the other hand, four patients had worsened; of these, two had died and two had a KPS=50 and an unfavourable prognosis. The presence of histological atypia has proved to be a significantly negative risk factor for survival (P=0.02) while an MIB score >4% was significantly correlated with an unfavourable outcome (death or worsening of neurological status). The "atypical" neurocytoma seems to be a distinct entity, with a less favourable prognosis and a higher tendency to recur.