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Central neurocytomas are WHO grade 2 neuroepithelial intraventricular tumors with fairly characteristic imaging features, appearing as heterogeneous masses of variable size and enhancement within the lateral ventricle, typically attached to the septum pellucidum. They are typically seen in young patients and generally have a good prognosis provided a complete resection can be achieved.
Extraventricular neurocytomas (previously known as cerebral neurocytomas) are very uncommon, considered distinct entity and are therefore discussed in a separate article.
Central neurocytomas are typically seen in young patients (70% diagnosed between 20 and 40 years of age) and account for less than 1% (0.25-0.5%) of intracranial tumors 10,11. There is no reported gender predilection 10.
Typically, central neurocytomas present with symptoms of increased intracranial pressure, headaches being most frequent, or seizures (especially tumors with extraventricular extension).
A relatively short clinical course, typically only a few months, is most common. Rarely central neurocytomas may be associated with sudden death secondary to acute ventricular obstruction 4. Also rare, is a sudden presentation due to intraventricular hemorrhage 7.
Central neurocytomas demonstrate neuronal differentiation and histologically appear similar to oligodendrogliomas which, historically, resulted in many tumors erroneously categorized.
The initial description classified them as WHO grade 1 lesions. However, this was upgraded in 1993 to WHO grade 2 as it was recognized that at least some of these tumors exhibited more aggressive behavior 10.
The vast majority of central neurocytomas are located entirely within the ventricles. Typical locations include 4:
lateral ventricles around foramen of Monro (most common): 50%
both lateral and 3rd ventricles: 15%
3rd ventricle in isolation: 5%
Central neurocytomas are usually friable grey-colored tumors, sometimes demonstrating areas of calcification and hemorrhage 11.
The cells are typically uniform and round with a salt and pepper finely speckled chromatin 11. They also demonstrate areas of variable architecture that are reminiscent of other tumors, including oligodendrogliomas, pineocytomas and neuroendocrine tumors 11.
Immunohistochemistry confirms the purely neuronal origin by positivity to neuronal markers such as 11:
neuron-specific enolase: positive
MAP2: usually positive
class III beta-tubulin: usually positive
Extraventricular neurocytomas are histologically similar but lack an intraventricular component 11.
Ganglioneurocytoma is a variant, usually of extraventricular neurocytomas, demonstrating a distinct ganglion cells component 6,11,12.
Central neurocytomas are usually hyperattenuating compared to white matter. Calcification is seen in over half of cases, usually punctate in nature 4,10. Cystic regions are frequently present, especially in larger tumors. Contrast enhancement is usually mild to moderate. Accompanying ventricular dilatation is often present.
isointense to grey matter
mild-moderate heterogeneous enhancement
typically iso to somewhat hyperintense compared to brain
numerous cystic areas (bubbly/swiss cheese appearance), many of which completely attenuate on FLAIR
prominent flow voids may be seen 10
calcification is common, typically punctate
hemorrhage (especially in larger tumors) is common
uncommonly results in ventricular hemorrhage
diffusion restriction of the solid component 13
may have a strong choline peak 13
glycine peak (3.55ppm) has also been reported 10
A tumor blush is frequently identified, with the mass supplied by choroidal vessels. No large feeding arteries are usually seen.
Treatment and prognosis
Complete surgical resection is usually curative (5 years survival 81%). When only incomplete resection is possible or extraventricular extension is present, then adjuvant radiotherapy (and sometimes chemotherapy) are added, although their benefit is not well established.
Cases of CSF dissemination have been reported, but are rare 10.
History and etymology
In 1982, Hassoun described central neurocytoma for the first time 2.
more frequent in childhood
more commonly in 4th ventricle
supratentorial tumors (esp in children) often have a significant extraventricular (parenchymal) component 4
homogeneous contrast enhancement
typically found in the 4th ventricle
usually older individuals 8
may have ependymoma components and look very similar 9
in patients with tuberous sclerosis
vivid contrast enhancement
mainly in children
typically show intense contrast enhancement
usually stronger contrast enhancement
history of primary (e.g. renal cell carcinoma)
surrounding vasogenic edema
less lace-like appearance (if any)
elevated MR perfusion (rCBV)
this is especially difficult in cases where there is a parenchymal component as histologically the tumors are very similar