Extraventricular Neurocytoma in Parietal Lobe

Extraventricular neurocytoma (EVN) was classified as a World Health Organization (WHO) grade II tumor; however, EVN is not fully understood; it presents a variable histological feature that included oligodendroglioma-like, neuropil-like matrix, ganglion or gangloid cells, perivascular pseudorosettes, vessel hyalinization, calcifications, and myxoid degeneration. In some very rare cases, atypical histological features such as increased mitotic figures, focal necrosis, endothelial cell proliferation, and Ki-67 index of >2% made this tumor more aggressive and more susceptible to recur. We present the case of a young patient who presents with a 2-year history of seizure without other symptoms. Magnetic resonance imaging reveals a parietal lobe and well-circumscribed lesion treated by gross total resection and adjuvant radiotherapy. Clear guidelines to treat this kind of lesions are not well established and there is not a consensus of correct treatment in these tumors.

A rare diagnosis of an extraventricular neurocytoma

Background: Extraventricular neurocytoma (EVN) is an extremely rare neoplasm of the central nervous system. As reported, it arises in a variety of locations, but mainly within the cerebral hemispheres. Despite its histological similarity with central neurocytoma (CN), EVN occurs outside the ventricular system and, in 2007, was recognized by the World Health Organization as a separate entity. Case Description: A 39-year-old man, with a ventriculoperitoneal shunt inserted for communicating hydrocephalus, was admitted at our Unit of Neurosurgery with a 1-month history of gait disturbance, postural instability, speech disorders, and occasional incontinence. Computed tomography scan and magnetic resonance imaging showed a mixed-density neoplasm in the left frontotemporal area, with anterior cerebral falx shift, and perilesional edema. The patient underwent surgical procedure; microsurgical excision of the lesion was performed through left pterional approach. Histopathological and immunohistochemical examination revealed monomorphic round cells of the neuronal lineage, with a percentage of Ki-67 positive nuclei <5% and no evidence of mitosis or necrotic areas. According to radiologic features, this pattern was compatible with the diagnosis of EVN. Patient had a favorable recovery and he is still in follow-up. Conclusion: Because of their rarity, clinical, radiologic, and histopathological characteristics of EVNs are not yet well defined, as well as the optimal therapeutic management. Whereas EVNs are rarely described in literature, we aimed to share and discuss our experience along with a review of the published literature.

A cerebellar neurocytoma with an excellent response to radiotherapy: a case report

Background: Extraventricular neurocytoma (EVN) is a rare central neurocytoma with neoplasms occurring in the brain parenchyma outside the ventricular system with similar biological behaviours and histopathological characteristics. Cases of EVN reported in the brainstem and cerebellum are fairly rare. In addition, very few cases with radiotherapy as the only treatment have been reported, and their outcomes were unclear.Case presentation: We reported an EVN of the brainstem and cerebellum confirmed by pathology in a 43-year-old male presenting with unprovoked nausea and dizziness. The patient showed a favourable outcome with only radiotherapy during the 2-year follow-up.Conclusions: Patients who have EVN may have a favourable prognosis with radiotherapy without surgery.