[Central neurocytoma. Immunohistochemical study: MIB1, p53 and bcl-2. Report of 5 cases].

To further characterize central neurocytoma, a rare intraventricular tumour described in 1982, we analyzed six tumours by immunohistochemistry for MIB1, p53 and bcl-2. bcl-2, an inhibitor of p53-mediated apoptosis is frequently expressed in gliomas, especially in tumors with wild-type p53. Its expression in peripheral neuroblastomas suggests a down-regulation during final terminal differentiation. Six tumors from five patients (one female/four males, age ranged from 18 to 63 years) were examined. All patients were alive from 2 to 88 months after initial surgical resection. On histological sections, tumours demonstrated a typical pattern. Synaptophysin staining was seen in all cases. Proliferation index was low (< 4.5%). bcl-2 was never expressed. p53 expression varied but within low values (< 10% of cells). These latter antibodies were rarely analyzed until now in this usually benign neoplasm which represents a well differentiated variant of neuron derived tumors.