Cerebral neurocytoma without ganglion cell differentiation.

Neurocytomas are rare neuronal tumours, and are defined as tumours comprising cells with neuronal differentiation; they commonly arise in the ventricles. We report a case of a cerebral neurocytoma in a young man who presented with hemiparesis. The tumour was a radiologically a well-circumscribed large cyst with solid mass; the histopathology showed a well-differentiated lesion comprising uniform, round cells with perinuclear halos in a neuropil background, and immunohistochemically positive for neuronal markers (synaptophysin, neuron-specific enolase and neurofilaments). We suggest that cerebral neurocytomas should be considered among the uncommon causes of a large intra-axial cystic mass with a solid component in young adults.