Extraventricular neurocytoma

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

Microscopic appearance

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

Immunophenotype
  • synaptophysin: positive and essential to the diagnosis 5
  • GFAP: may be positive if an astrocytic component is present
  • IDH R132H: negative
Genetics

IDH mutations are absent and are critical in distinguishing an extraventricular neurocytoma from the more common oligodendroglioma, as both can demonstrate 1p19q co-deletion 5

Variants

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. 

MRI 

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

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

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Article information

rID: 10924
Synonyms or Alternate Spellings:
  • Extraventricular neurocytoma
  • Cerebral neurocytomas

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