= name reserved for neurocytoma that occurs in ventricles

Incidence: 0.25–0.5% of intracranial tumors

Origin: ? bipotential progenitor cells capable of both neuronal + glial differentiation

Histo: solid sheets / large lobules of small round to ovoid neoplastic cells with delicate vascular network + intervening irregular patches of fibrillary neuropils; pineocytomatous rosettes (not in oligodendroglioma)

Immunohisto: synaptophysin, neuron-specific enolase

Mean age: 29 years (range, 8 days to 67 years); M=F

• symptoms of increased intracranial pressure

Location:

1. lateral ventricle ± extension into 3^rd ventricle
   Site: septum pellucidum, ventricular wall
2. extraventricular: parenchyma, cerebellum, spinal cord

• well-circumscribed lobulated mass
• frequently “bubbly” appearance ← presence of multiple cysts
• calcifications (50%)
• moderate to strong enhancement

CT:

• hyperattenuating lesion

MR:

• lesion T1-isointense + T2-hyperintense to gray matter
• ± prominent flow voids
• increased T2 signal intensity in adjacent periventricular white matter

MR spectroscopy:

• presence of glycine (3.55 ppm)

Rx: usually curative resection

Cx: recurrence after resection, CSF dissemination