Central neurocytoma (CN), first described in 1982 by Hassoun and colleagues, is a neoplasm of neuroepithelial origin, with intermediate malignancy (WHO grade II), detectable with both computed tomography and magnetic resonance imaging.
Central neurocytomas are typically seen in young patients (20-40 years of age), and accounts for less than 1% (0.25-0.5%) of intracranial tumours. There is no reported gender predilection.
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. Also rare, is a sudden presentation due to intraventricular haemorrhage.
Only 3 previous cases in which CN presented with co-occurring psychotic symptoms were found in the PubMed database. A report presents the case of a 27-year-old patient with paranoid syndrome without neurological symptoms, in whom magnetic resonance imaging confirmed a large intracranial tumor located predominantly in the right lateral ventricle and third ventricle reaching down to the hypothalamus. Resection of the tumor (histopathologically a CN) resulted in complete remission of the psychotic symptoms. This case supports the need for neuroimaging in all patients with first-episode psychosis because of the possibility of neurologically silent brain tumors. Quick diagnosis in such cases is crucial for the selection of treatment methods and prognosis 1).
Fairly characteristic imaging features, appearing as heterogeneous masses of variable size and enhancement within the lateral ventricle.
The vast majority of central neurocytomas are located entirely within the ventricles. Typical locations include:
lateral ventricles around foramen of Munro (most common): 50%
both lateral and 3rd ventricles: 15%
3rd ventricle in isolation: 5%
Extra ventricular neurocytomas (or cerebral neurocytomas) are distinctly uncommon, and thought to be a separate entity due to the tendency to have prominent ganglionic or glial differentiation.
Central neurocytomas are usually hyperattenuating compared to white matter. Calcification 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 ventricular dilatation often present.
T1 isointense to grey matter heterogenous
T1 C+ mild-moderate heterogeneous enhancement
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
MR spectroscopy may have a strong choline peak glycine peak (3.55ppm) has also been reported
A tumour blush is frequently identified, with the mass supplied by choroidal vessels. No large feeding arteries are usually seen.
Central neurocytomas demonstrate neuronal differentiation and histologically appear similar to oligodendrogliomas. This has historically has resulted in many tumours erroneously categorised. They lack co-deletion of 1p19q which is characteristic of oligodendroglioma. The cells are typically uniform and round with a salt and pepper appearance.
The tumor is composed of small round cells with neuronal differentiation.
The initial description classified them as WHO grade I lesions, however this was upgraded in 1993 to WHO grade II as it was recognised that at least some of these tumours exhibited more aggressive behaviour 10.
Purely neuronal origin is demonstrated positivity to neuronal markers such as:
neuronal specific enolase
Ganglioneurocytoma: shows differentiation towards ganglion cells.
ependymoma more frequent in childhood more commonly in 4th ventricle
supratentorial tumours (esp in children) often have a significant extraventricular (parenchymal) component
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 (SGCA) in patients with tuberous sclerosis vivid contrast enhancement
choroid plexus papilloma (CPP) mainly in children typically show intense contrast enhancement
intra ventricular metastasis older patients usually stronger contrast enhancement history of primary (e.g. RCC)
oligodendroglioma this is especially difficult in cases where there is a parenchymal component as histologically the tumours are very similar.
They generally have a good prognosis provided a complete resection can be achieved.
Cases of CSF dissemination have been reported, but are rare.
Only 3 previous cases in which CN presented with co-occurring psychotic symptoms were found in the PubMed database. This report presents the case of a 27-year-old patient with paranoid syndrome without neurological symptoms, in whom magnetic resonance imaging confirmed a large intracranial tumor located predominantly in the right lateral ventricle and third ventricle reaching down to the hypothalamus. Resection of the tumor (histopathologically a CN) resulted in complete remission of the psychotic symptoms. This case supports the need for neuroimaging in all patients with first-episode psychosis because of the possibility of neurologically silent brain tumors. Quick diagnosis in such cases is crucial for the selection of treatment methods and prognosis 2).
Kawakami et al. present the first case of central neurocytoma with a component suggesting ependymal-like differentiation as an unclassified glioneuronal tumor. The patient was a 26-year-old Japanese man with a brain tumor extending from the frontal wall of the bilateral lateral ventricles to the corpus callosum. Histologically, the tumor's neuronal component consisted of small bland looking cells with fine, delicate, neuropil-like processes forming a rosette structure; its glial component consisted of tumor cells with thick processes arranged around the thinly walled vessels, resulting in a perivascular pseudo-rosette formation and indicating ependymal-like differentiation. Immunohistochemically, the cytoplasm of the tumor cells with ependymal-like features was positive for glial fibrillary acidic protein and negative for synaptophysin, while the tumor component with neuronal features showed the opposite immunohistochemical staining pattern. Most of the tumor cells were positive for Olig2, but EMA, D2-40, CD99, p53, and mutant IDH-1 (R132H) were totally negative. Its Ki-67 labeling index was less than 1 %. Histologically, this tumor was diagnosed as a central neurocytoma with an ependymoma-like glial component, and its tumor grade was estimated at grade II. The tumor location, infiltrating the corpus callosum, and histology were distinctive and might represent a peculiar subtype of glioneuronal tumor 3).