Central neurocytoma

Incidence

Central neurocytomas are rare.

Origin

The tumor cells have the ultrastructural features of neurons, with evidence of markers of neuronal differentiation.

Macroscopic appearance and general characteristics

Central neurocytoma is a well-circumscribed, polylobular mass situated in the lateral ventricles, typically in the region of the foramen of Monro with a characteristic attachment to the septum pellucidum. Commonly, cysts and areas of central necrosis are seen. Extension to the third ventricle is possible. The tumor can obstruct CSF pathways with clinical signs of increased intracranial pressure. Central neurocytoma corresponds to Grade I.

Microscopic appearance (image 2)

Histologically neurocytoma is composed of uniform round cells with clear cytoplasm and easily recognizable cell membrane. This pattern can mimic oligdendroglioma. In some areas elements of the neuropil can be recognized, which can be confirmed by electron microscopy and by the expression of neuronal marker proteins. The nuclei display a typical "salt and pepper" chromatin pattern.

Imaging features (see case reports)

- CT scan

On non-contrast scans the tumor is slightly hyperdense, with multiple small cysts and calcifications. A broad based attachment to the superolateral ventricular wall and attachment to the septum pellucidum is typical. Contrast enhancement is moderate.

- MRI

Central neurocytoma is mainly isointense relative to cortical grey matter on both T1- and T2 weighted spin-echo images. Areas of inhomogeneous intensity are due to calcification, cystic spaces and vascular flow voids. Attachment to the septum pellucidum and the broad based attachment to the superolateral ventricular wall is better demonstrated on multiplanar imaging (image 3). Contrast enhancement is moderate.

Differential diagnosis

The differential diagnosis includes oligodendroglioma, subependymal giant cell astrocytoma, pilocytic astrocytoma and ependymoma.

Case reports

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Central neurocytoma

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