Pseudopapillary neurocytoma of temporal lobe with glial differentiation.

We present a case of cerebral neurocytoma with unusual pseudopapillary pattern, which was a predominant feature in the tumor and was characterized histologically by hyalinized vascular cores surrounded by a single or multilayered small round cells. Vascular hyalinization was also evident in the linear arborizing capillary networks in the cellular mass of the tumor. Immunohistochemically, the tumor cells were strongly positive for synaptophysin and neuron-specific enolase except some cells lining the pseudopapillae, which showed immunoreactivity for glial fibrillary acidic protein, vimentin and S-100 protein. Ultrastructural examination revealed neuritic process of the tumor cells with occasional synaptic structures and neurosecretory granules. This report suggests that neurocytoma should be included in the differential diagnosis of papillary tumors in the central nervous system.