Extraventricular neurocytomas, previously known as cerebral neurocytomas, are rare WHO grade II primary CNS neoplasms usually arising in the cerebral hemispheres. They are, as the name implies, extraventricular versions of central neurocytomas.
These tumours are reported at essentially all ages without a sex predilection 5.
No specific clinical features are present, with presentation depending on the size and location fo the tumour. Seizures, headache and focal neurological defects are typical manifestations.
Extraventricular neurocytomas can occur anywhere in the CNS, including the spinal cord 5.
The tumours are of neuronal origin and are similar to the comparatively more common central neurocytomas which are intraventricular. They too demonstrate a variety of histological patterns but are generally less cellular densely 5.
- synaptophysin: positive and essential to the diagnosis 5
- GFAP: may be positive if an astrocytic component is present
- IDH R132H: negative
When a distinct ganglion cell population is present the term ganglioneurocytoma can be used 5.
Lesions tend to be generally circumscribed, complex and sometimes large, complex, and variably enhancing masses. They are often partly or mainly cystic and calcification is not uncommon(>10%). They may or may not be associated with peritumoral oedema.
In most instances, they are well-defined, often mixed cystic heterogeneously solid lesions that involve the deep white matter or the cortical grey matter of the cerebral hemispheres.
T1 C+: solid portions may show varying degrees of enhancement
Treatment and prognosis
As these are relatively indolent and well-demarcated tumours, complete surgical resection can effect a cure 5. CSF dissemination is reported but is rare 5.
- ganglioglioma and gangliocytoma
- pleomorphic xanthoastrocytoma
- pilocytic astrocytoma
- diffuse astrocytoma, particularly gemistocytic astrocytoma and oligodendrogliomas
- papillary glioneuronal tumour
- rosette-forming glioneuronal tumours (usually midline and often posterior fossa)
- diffuse leptomeningeal glioneuronal tumour (when leptomeningeal spread is prominent)
- 1. Yang GF, Wu SY, Zhang LJ et-al. Imaging findings of extraventricular neurocytoma: report of 3 cases and review of the literature. AJNR Am J Neuroradiol. 2009;30 (3): 581-5. doi:10.3174/ajnr.A1279 - Pubmed citation
- 2. Brat DJ, Scheithauer BW, Eberhart CG et-al. Extraventricular neurocytomas: pathologic features and clinical outcome. Am. J. Surg. Pathol. 2001;25 (10): 1252-60. Am. J. Surg. Pathol. (link) - Pubmed citation
- 3. Tortori-donati P, Fondelli MP, Rossi A et-al. Extraventricular neurocytoma with ganglionic differentiation associated with complex partial seizures. AJNR Am J Neuroradiol. 1999;20 (4): 724-7. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Furtado A, Arantes M, Silva R et-al. Comprehensive review of extraventricular neurocytoma with report of two cases, and comparison with central neurocytoma. Clin. Neuropathol. 29 (3): 134-40. Clin. Neuropathol. (link) - Pubmed citation
- 5. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK "WHO Classification of Tumours of the Central Nervous System. 4th Edition Revised" ISBN: 9789283244929