Clinicopathological analysis of nine consecutive central nervous system primitive neuroectodermal tumors in a single...

The objective of this study was to determine the outcome of central nervous system primitive neuroectodermal tumors (CNS PNETs) and to clarify the histopathological findings as prognostic factors. We performed a retrospective analysis of nine consecutive patients with CNS PNETs who underwent treatment at our institute between 1993 and 2011. All patients were treated by surgical resection followed by chemoradiotherapy. Additional treatment, including surgical resection, was performed at relapse. Expression of immunohistochemical markers was examined for neuronal, astrocytic, mesenchymal, and epithelial differentiation, and also for TP53, O(6)-methylguanine-DNA methyltransferase, and Ki-67. Five-year progression-free survival was 18.2 % and the overall survival was 52.5 %. Five the 9 patients had recurrence and 4 patients died during the median follow-up period of 41.1 months. All 4 patients died of dissemination not local recurrence. After relapses, the extent of differentiation was different in each case and TP53 changed to positive or negative, but the Ki-67 labeling index did not reveal any differences between primary and recurrent tumors. A treatment procedure to prevent and treat dissemination of CNS PNETs should be established. Because the pathological change after relapse was different in each case, definitive histopathological prognostic factors for CNS PNETs are still difficult to propose.