RESUMO
Central neurocytomas (CNs) are usually considered benign; however, some subsets of these tumors with histologic atypia and elevated proliferation potential have been reported to have a poor outcome. It has been proposed that those CNs exhibiting a MIB-1 labeling index (LI) greater than 2% and/or vascular proliferation be defined as atypical central neurocytoma (ACN). Two cases of ACN are reported here. Case 1 was a 13-year-old male who complained of headache. An MRI showed an enhancement of the tumor in the third ventricle and left lateral ventricle. The tumor was completely removed transcortically by a left frontotemporal craniotomy. The tumor showed anaplastic features, including microvascular proliferation, mitosis, and necrosis. The MIB-1 LI was 7.8%. The patient received 50Gy of focal irradiation. After 16 months of follow-up, no recurrence was observed. Case 2 was a 17-year-old female who presented with headache. An MRI showed an enhancement of the tumor in the right lateral ventricle. To preserve the internal cerebral vein, the tumor was partially removed by the transcingulate approach after a bifrontal craniotomy. Histologically, the tumor displayed the typical features of a CN. The MIB-1 LI was 7.0%. Complete remission was achieved through 50Gy of focal irradiation. After 15 months of follow-up, there was no recurrence. The differences in the histopathological findings in these two cases indicate the presence of a variety of histopathological features among ACNs.