Central neurocytoma

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Done

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Glioneuronal and neuronal tumours

Definition

• Essential:
• Intraventricular localization AND
• Oligodendroglioma-like monomorphic cells AND
• Synaptophysin expression AND (for unresolved lesions)
• Methylation profile of central neurocytoma

• Desirable:
• Young adult patient
• In most cases, no sign of malignancy

Grading

• WHO Grade 2

• If Ki67>3% we it will be anaplastic but there is current no WHO for >grade 2

Number

• Mean age: 28.5 yrs
• Rare paediatric cases

• Male: female 1.02: 1

• 0.5% of all intracranial tumours

Clinical features

• Hydrocephalus

• Short clinical history 1-3 months

Origin

• Precursors of neuronal cells that exist within the septum pellucidum

Localisation

• Supratentorial
• Lateral ventricle (anterior portion)
• Attachment to the septum pellucidum
• Growth pattern
• Grows significant size within the lateral ventricle (Common) OR
• grow into the third ventricle through the foramen of Monro (Rare)

Radiology

CT

• Hyperdense compared to white matter.

• Calcification is seen in over half of cases, usually punctate in nature.

• Cystic regions are frequently present, especially in larger tumours.

• Contrast enhancement is usually mild to moderate.

• Accompanying hydrocephalus often present.

 

MRI

• T1
• Isointense to grey matter
• Heterogeneous

• T1 C+
• Mild-moderate heterogeneous enhancement (like CT)

• T2/FLAIR
• Typically iso to somewhat hyperintense compared to brain
• Numerous cystic areas (bubbly appearance), many of which completely attenuate on FLAIR
• Prominent flow voids may be seen

• GE/SWI
• Calcification is common, typically punctate
• Haemorrhage (especially in larger tumours) is common
• Uncommonly results in ventricular haemorrhage

• DWI
• Diffusion restriction of the solid component

• MR spectroscopy
• May have a strong choline peak
• Glycine peak (3.55ppm) has also been reported

Image

 

 

Angiography

• A tumour blush is frequently identified, with the mass supplied by choroidal vessels. No large feeding arteries are usually seen.

Histopathology

Macroscopic

• Friable grey-coloured tumours

• Sometimes has calcification and haemorrhage

• They are well circumscribed, can be lobulated, contain cysts, and have heterogenous signal and flow voids, and they can also contain calcifications

Microscopic

• The cells are typically uniform and round with a salt and pepper finely speckled chromatin

• Lesion demonstrate areas of variable architecture that are reminiscent of other tumours, including
• Oligodendrogliomas
• Pineocytomas
• Neuroendocrine tumours

• Ki67<2%

Immunophenotype

• Positive
• Synaptophysin: positive
• NeuN: positive
• Neurone-specific enolase: positive
• MAP2: usually positive
• Class III beta-tubulin: usually positive

• Negative
• GFAP and IDH-1 R132H are negative

Genetic profile

• MYCN gain

• Do not have 1p/19q codeletion

Management

General

• After treatment, patients should have long-term follow-up imaging as surveillance for tumour recurrence.

Surgery

• Total resection is often curative.
• After gross total resection, radiation therapy is generally not necessary
• They occasionally encase the columns of Fornix, in which case complete surgical excision maybe contraindicated to preserve memory

• Subtotal resection can be followed by stereotactic radiosurgery, especially if Ki67 labelling is > 2–4%.

Radiotherapy (Leenstra et al 2007)

• Postoperative RT improved local control at 10 years (75% with RT vs. 51% without RT, p = 0.045)
• However, this did not translate into a survival benefit.

Chemotherapy for recurrent and inoperable tumours

• Alkylating agents (carmustine, cyclophosphamide, ifosfamide, lomustine)

• Platinum-based agents (carboplatin and cisplatin)

• Etoposide

• Topotecan

• Vincristine

Prognosis

• Kaur et al 2013
• Total resection can be curative.
• 5 year local control after gross total resections: 85%
• 5 years survival after gross total resection 5 years: 81%
• Recurrence risk after subtotal resection varies with the Ki67 labelling index.
• Ki67 <4% had no recurrence at 4 years after subtotal resection.
• Ki67 >4% at subtotal resection, recurrence was found in
• 50% of patients at 2 years
• 75% at 4 years.
• Most local recurrences occur within 3–6 years.
• Recurrence is more common in extraventricular neurocytoma.
• Rare CSF dissemination
• If partial resection then need adjuvant radio/chemotherapy

Differential diagnosis

• Ependymoma
• More frequent in childhood
• More commonly in 4th ventricle
• Supratentorial tumours (esp in children) often have a significant extraventricular (parenchymal) component 4

• Intraventricular meningioma
• Homogeneous contrast enhancement
• Well circumscribed mass

• Subependymoma
• Typically found in the 4th ventricle
• Usually older individuals
• May have ependymoma components and look very similar

• Subependymal giant cell astrocytoma
• In patients with tuberous sclerosis
• Vivid contrast enhancement

• Choroid plexus papilloma
• Mainly in children
• Typically show intense contrast enhancement

• Intraventricular metastasis
• Older patients
• Usually stronger contrast enhancement
• History of primary (e.g. renal cell carcinoma)

• Oligodendroglioma
• This is especially difficult in cases where there is a parenchymal component as histologically the tumours are very similar

• Cerebral neuroblastomas:
• Central neuroblastoma
• 3rd ventricle
• Young adults
• Histologically more like oligodendroglioma
• Central neurocytoma
• Other intraventricular locations: lateral + 3rd and 4th

• Cerebral neurocytomas

• Extraventricular neurocytomas
• They arise in CNS parenchyma
• Have similar histology as central neurocytomas