Extraventricular neurocytoma

Extraventricular neurocytoma is a rarer subtype with a peak incidence in the 20-34 years age group ¹⁾.

It may be located in the cerebral parenchyma, cerebellum, thalamus, brainstem, pineal region, and spinal cord. Tumor cells can be focally infiltrative into the surrounding tissue. Pathology findings include vessel wall hyalinization and ganglionic differentiation.

Immunohistochemistry is positive for synaptophysin in the cytoplasm and neuropil. Neu-N staining is often positive. 1p and 19q deletions, in isolation or in combination, can be seen in extraventricular neurocytoma ²⁾, and it is possible that some of these tumors with 1p/19q co-deletion are actually astrocytomas. Neither IDH1/2 mutation nor MGMT methylation has been reported, therefore, if extraventricular neurocytoma is suspected on histological grounds, it is imperative to check for IDH mutation to rule out diffuse astrocytoma with neurocytic differentiation ³⁾.

Recurrence is more common in extraventricular neurocytoma.

A case of atypical EVN in a 23-year-old man; Computed Tomography and Magnetic Resonance Imaging features of the mass are described, and differential diagnosis is illustrated. In light of the high variability of imaging presentation, the definitive diagnosis of EVN remains histologic. Although some cases have already been reported in the literature, we believe that the description of our case could be useful to increase the knowledge of this insidious tumor, which has gained recognition only over the past 2 decades and should be included in the differential diagnosis in young patients who present brain tumors ⁴⁾.

A case of EVN with diffuse ganglioid differentiation in a 70-year-old male that arose in the midline parasellar region and extended into the third ventricle. This is the oldest such patient-reported. Despite prior reports that extremes of age are associated with more aggressive behavior, the tumor, in this case, did not exhibit such an aggressive course.

The patient responded well to therapy despite older age, ganglioid differentiation, and higher mitotic index ⁵⁾.

A Brazilian 27-year-old man who presented with progressive vision loss during the last 4 years and serious bilateral keratoconus. We also review the epidemiological, clinical, radiological, pathological, and treatment features of the 12 reported cases. The patient developed left amaurosis and right temporal hemianopsia after undergoing bilateral corneal transplantation, which was detected during campimetry testing, and subsequently underwent magnetic resonance imaging, which revealed a huge hypophyseal tumor. The endocrinological evaluation revealed a complete loss of pituitary function. The patient was referred to our department and underwent a two-step surgery (using a transsphenoidal approach and cranio-orbital zygomatic approach) based on the diagnosis of an extraventricular central nervous system neurocytoma. Tumor removal was successful, and the patient was discharged 3 weeks after admission ⁶⁾.