At a glance
- WHO grade
- CNS WHO grade 2 (central neurocytoma)
- Typical location
- Lateral ventricle, attached to the septum pellucidum
- Age
- Young adults (20s–30s)
- Key imaging
- “Bubbly” enhancing intraventricular mass, calcification
- Markers
- Synaptophysin-positive
Overview
Central neurocytoma was described by Hassoun and colleagues in 1982 as an intraventricular tumour made of small, uniform neuronal cells, which had previously been mistaken for oligodendroglioma or ependymoma[1]. It is a CNS WHO grade 2 tumour[2]. It typically arises from the septum pellucidum or the wall of the lateral ventricle near the foramen of Monro. Tumours with similar histology outside the ventricles are classified as extraventricular neurocytomas and behave more variably. A raised proliferation index (often taken as a Ki-67 above 2–3%) defines an atypical neurocytoma with a higher risk of recurrence.
Clinical presentation
Most patients present with symptoms of raised intracranial pressure from obstructive hydrocephalus at the foramen of Monro: headache, nausea, vomiting and visual disturbance. Intratumoural haemorrhage can cause acute deterioration. Focal deficits are uncommon.
Imaging
MRI shows a well-circumscribed, lobulated, heterogeneous intraventricular mass with multiple small cysts (a “soap-bubble” appearance) and moderate enhancement, often with flow voids and calcification on CT. The differential includes subependymoma, subependymal giant-cell astrocytoma (in tuberous sclerosis), ependymoma, choroid plexus tumours, intraventricular meningioma and oligodendroglioma.
Surgical management
Gross-total resection is the treatment of choice and is associated with excellent long-term control. Approaches include the anterior interhemispheric transcallosal route, which avoids a cortical incision and works well with hydrocephalus or bilateral tumour, and the transcortical (transfrontal) route through the middle frontal gyrus, which is easier with large ventricles but carries a higher risk of seizures[3,4]. Endoscopy has a role for biopsy, septostomy and small tumours.
- Identify the foramen of Monro, the thalamostriate and septal veins and the fornix early.
- The tumour is often vascular, with supply from the choroidal and septal arteries; coagulate feeding vessels at the attachment.
- Debulk internally and deliver the tumour away from the fornix and the internal cerebral veins.
- Leave an external ventricular drain and manage hydrocephalus; some patients need a shunt or septostomy.
Outcomes
After gross-total resection, recurrence is uncommon. Subtotal resection, especially of an atypical tumour, is usually followed by fractionated radiotherapy or radiosurgery. Complications include memory deficits from forniceal injury, venous infarction, seizures, intraventricular haemorrhage and persistent hydrocephalus.
Take-home
Surgical pearls
- A bubbly intraventricular mass at the foramen of Monro in a young adult is a neurocytoma until proven otherwise.
- Aim for gross-total resection; it is often curative.
- Protect the fornix and the deep veins above all.
- Check the Ki-67 index: atypical tumours need closer follow-up and often radiotherapy.
Related
References
- 1.Hassoun J, Gambarelli D, Grisoli F, et al. Central neurocytoma: an electron-microscopic study of two cases. Acta Neuropathol. 1982;56(2):151-156.
- 2.Louis DN, Perry A, Wesseling P, et al. The 2021 WHO Classification of Tumors of the Central Nervous System: a summary. Neuro Oncol. 2021;23(8):1231-1251.
- 3.Apuzzo ML, Chikovani OK, Gott PS, et al. Transcallosal, interfornicial approaches for lesions affecting the third ventricle: surgical considerations and consequences. Neurosurgery. 1982;10(5):547-554.
- 4.Rhoton AL Jr. The lateral and third ventricles. Neurosurgery. 2002;51(4 Suppl):S207-S271.
General education for medical professionals. It summarises published literature and is not advice for any individual patient or a substitute for supervised surgical training.