Cerebral neurocytoma. A new subset of benign neuronal tumors of the cerebrum

Central neurocytomas: research trends, most cited papers, and scientometrics analysis to date

Central neurocytoma is the most common primary intraventricular tumor in adults being classified by the World Health Organization (WHO) as a benign grade II tumor with a good prognosis. Given the recent advances with regard to this tumor, a bibliometric analysis was due to study the future direction of research for neurocytomas. A comprehensive Elsevier's Scopus database search was performed to capture all published and indexed studies to date relevant to neurocytoma. A discrete set of validated bibliometric parameters were extracted and analyzed on R v4.1.3. A total of 1002 documents were included in our analysis covering a period between 1910 and 2021 (111 years). Around 98.5% of the documents were multi-author publications with a collaboration index (CI) of 4.21. Acta Neuropathologica, The American Journal of Surgical Pathology, and Cancer were the journals to include the highest number of top ten cited articles (2 out of 10 most cited articles, 20%). Switzerland (4 out of 10, 40%) accounted for the country to have the highest number of top 10 most cited articles with the USA (5588 out of 16,395 citations, 34.1%) having the greatest number of citations. Lastly, our analysis reported an annual growth rate of 6.9% for the number of papers produced by year. This is the first bibliometric analysis to study the top 10 most cited articles with regard to neurocytomas. A shift from histopathologic and clinical symptoms towards the treatment and management of the tumor was observed in our analysis.

Extraventricular neurocytomas: a systematic review of the literature in the pediatric population

Extraventricular neurocytomas (EVNs) are rare neuroepithelial neoplasms of the central nervous system that were first described in 1997. Most studies in patients with EVNs have incorporated mixed age groups. The tumor's clinical behavior specifically in children has not been explored in depth, while a detailed statistical analysis has never been performed in this age group. Hence, we performed a systematic review to address possible prognostic factors and the appropriate management in children with EVNs. Relevant studies were identified by searching the MEDLINE and SCOPUS databases. We included studies concerning patients 18 years of age or younger who were histologically diagnosed with EVNs. A total of 52 studies with 79 patients were included. The mean age of the patients was ~ 10 years with a male predilection (~ 2:1). Most of these tumors were located in the frontal (49%) lobe. We observed that gross total resection of the tumor was significantly lower in cases of atypical EVNs (p < 0.05). Additionally, atypical EVNs were associated with worse overall survival compared to typical EVNs (p = 0.05). Children 4 years of age or under had a worst outcome (p = 0.001). The patient's sex and the extent of the tumor's resection did not appear to affect the prognosis in a statistically significant manner. Contrary to the results of previous studies, the use of adjuvant radiotherapy or chemotherapy for the treatment of EVNs was not associated with better outcomes in the pediatric population. Thus, a less aggressive management of children with EVNs compared to the adult population is suggested.

Mesial temporal extraventricular neurocytoma (mtEVN): A case report and literature review

Aim

We describe a case of mesial temporal extraventricular neurocytoma (mtEVN) in a 23-year-old male presenting with drug-resistant seizures and review the literature on this rare tumor.

Methods

A PubMed search was queried using the MeSH term "neurocytoma" and key search terms "extraventricular", "temporal", and "epilepsy". Titles and abstracts were screened for temporal neurocytomas. References were reviewed to identify further studies.

Results

Twenty case reports were selected comparing the presentation, radiological, histopathological, and surgical outcomes of neocortex temporal EVNs (ntEVN) and mtEVNs.

Conclusion

Gross total resection of mtEVNs under intraoperative electrocorticography monitoring typically affords an excellent prognosis and successful seizure control.

Complete resection of hypervascularised extraventricular neurocytoma after preoperative embolisation

A 13-year-old female arrived at the Emergency Department with a two-week history of headache, and bilateral papilloedema on examination. The initial study with CT and MRI showed a large multicystic left frontal mass with calcification surrounded by peripheral oedema, subacute intralesional bleeding and association of multiple large vessels. She was initially operated on in another centre where a subacute haematoma was found, evacuating to multiple vessels and arteriolised veins. Despite the earlier neuroimaging findings, arteriovenous malformation (AVM) was suspected, so she was referred to our centre for further treatment. We performed angiography, MR angiography and MRI with advanced sequences, diagnosing a highly vascularised intra-axial tumour which was embolised. The patient was then definitively operated on, with the resulting finding of extraventricular neurocytoma (EVN). EVN are extremely rare lesions, not previously described in the literature as hypervascularised lesions, which in our case required prior angiography and embolisation for proper diagnosis and adequate management.

Intramedullary central neurocytoma of the thoracic spinal cord: A case report and literature review

Central neurocytomas (CNs) are rare benign tumors located in the central nervous system with a good prognosis. These tumors are predominantly located in the lateral ventricle near the foramen of Monro or in the third ventricle. Similar tumors that are located outside the ventricle are also called extraventricular neurocytomas, and have an even lower morbidity. Until now, several tumors have been identified in the thalamus, cerebellum, pons, medulla oblongata and spinal cord. In total, 24 cases of neurocytomas located in the spinal cord have been reported in English journals. The present study reported a patient with an intramedullary central neurocytoma of the thoracic spinal cord, diagnosed from clinical features, imaging findings, pathology and immunohistochemistry. The present case report also outlined the prognosis of the patient and reviewed the literature currently available on CNs located in the spinal cord.

Congenital Extra-Ventricular (Ganglio)Neurocytoma of the Brain Stem: A Case Report

Extraventricular neurocytoma (EVN) is an extremely rare tumor of neuroglial origin with a tendency toward ganglionic or glial differentiation. In the 2016 World Health Organization Classification, EVN was classified as a grade II tumor and described as a neoplasm with good outcome. However, the presence of cellular atypia is an important unfavorable prognostic factor. Here, we describe the first case of a patient with a congenital EVN localized in the brainstem. After a sub-total resection, his disease rapidly progressed despite several chemotherapies, including molecular targeting approaches. He died 13 months after diagnosis. In conclusion, we report an atypical case of EVN presenting an extremely aggressive behavior, despite the absence of cellular atypia. The brainstem origin and the age of the patient may have represented two important prognostic factors for our patient.

Central Neurocytoma: A Review of Clinical Management and Histopathologic Features

Central neurocytoma (CN) is a rare, benign brain tumor often located in the lateral ventricles. CN may cause obstructive hydrocephalus and manifest as signs of increased intracranial pressure. The goal of treatment for CN is a gross total resection (GTR), which often yields excellent prognosis with a very high rate of tumor control and survival. Adjuvant radiosurgery and radiotherapy may be considered to improve tumor control when GTR cannot be achieved. Chemotherapy is also not considered a primary treatment, but has been used as a salvage therapy. The radiological features of CN are indistinguishable from those of other brain tumors; therefore, many histological markers, such as synaptophysin, can be very useful for diagnosing CNs. Furthermore, the MIB-1 Labeling Index seems to be correlated with the prognosis of CN. We also discuss oncogenes associated with these elusive tumors. Further studies may improve our ability to accurately diagnose CNs and to design the optimal treatment regimens for patients with CNs.

Central Versus Extraventricular Neurocytoma in Children: A Clinicopathologic Comparison and Review of the Literature

BACKGROUND

Central neurocytomas (CN) are rare pediatric CNS tumors most often with a benign clinical course. Occasionally, these tumors occur outside the ventricles and are called extraventricular neurocytomas (EVN). We present a retrospective institutional analysis of children with neurocytoma with prolonged follow-up.

PROCEDURE

Twelve patients were diagnosed with neurocytoma at our institution between 1993 and 2004.

RESULTS

Six patients were male and the median age at diagnosis was 12 years (1.5 to 16 y). Seven patients had CN and 5 had EVN. Presenting symptoms included headaches (67%), vomiting (50%), nausea (33%), seizures (33%), and mental status changes (25%). Obstructive hydrocephalus was present at diagnosis in 42% of the cases. Younger age and seizures were more common in patients with EVN. Gross total resection (GTR) was achieved in 42% (5/12) of the patients. Patients with GTR received no adjuvant therapy upfront; 1 patient subsequently had recurrence with leptomeningeal disease. Patients with subtotal resection received additional treatment: 1 underwent reoperation (GTR), 2 patients received focal radiation, 2 patients received adjuvant chemotherapy, and 2 patients received craniospinal irradiation followed by chemotherapy. The 20-year overall survival for this cohort was 83% with event free survival of 56%. Overall survival for CNs was 100%, versus 40% for EVN. Event free survival for CNs was 57% and 53% for the EVNs. An MIB-1 fraction >2% was associated with worse prognosis.

CONCLUSIONS

Neurocytomas are rare brain tumors in children usually cured with GTR. Adjuvant focal radiation therapy and/or chemotherapy may improve disease control in cases with subtotal resection, but case-by-case analysis should be done. EVNs might be associated with worse outcome due to a higher proliferative index.

Immunohistochemical and Ultrastructural Studies of Oligodendrogliomas Revealed Features of Neuronal Differentiation

In an attempt to characterize differentiation in oligodendrogliomas, 39 cases were examined immunohistochemically with 5 neuronal markers, synaptophysin, neuron- specific enolase, neurofilament proteins, protein gene product (PGP) 9.5, and micro tubule-associated protein 2 (MAP2), in addition to glial fibrillary acidic protein (GFAP). Positive immunolabeling was obtained for neuron-specific enolose in 29 cases (74%), synaptophysin in 21 cases (54%), PGP 9.5 in 33 cases (85%), and MAP2 in 23 cases (59%). All cases were negative for neurofilament, and 90% stained for GFAP. Eight cases were further studied ultrastructurally, and in five cases features of neuronal differentiation were identified in some of the typical neoplastic oligodendro cytes—small neuritic cellular processes with microtubules and focal synapse-like junc tions, as well as sparse neurosecretory granules. It was concluded that, both immuno histochemically and ultrastructurally, oligodendrogliomas may exhibit features of neuronal differentiation. These previously unreported features of oligodendrogliomas call into question conventional immunohistochemical and electron microscopic crite ria used in distinguishing oligodendrogliomas from tumors showing similar histologic appearance, especially central neurocytomas and dysembryoplastic neuroepithelial tu mors. Int J Surg Pathol 2(1):47-56 1994

Hypothalamic Extraventricular Neurocytoma (EVN) in a Pediatric Patient: A Case of EVN Treated with Subtotal Removal Followed by Adjuvant Radiotherapy

Extra ventricular neurocytoma (EVN) is a rare brain tumor with histologic features similar with a central neurocytoma, but located outside of the ventricular system. In this study, we present an unusual case of hypothalamic EVN in a 14-year-old patient. The patient underwent subtotal removal and had tumor relapse. The patient was then treated using intensity modulated radiation therapy, and the tumor remained stable for 24 months. This case report may be important in that this is the first pediatric case of EVN located in the hypothalamic region. EVN has similar radiologic features with pilocytic astrocytomas and therefore a hypothalamic EVN may be misdiagnosed as a hypothalamic glioma. Also, the pathologic-radiologic-clinical correlation of EVN located in the hypothalamic area may be different from that of EVNs originating from other usual sites.

Neurocytoma arising from a mature ovary teratoma: a case report

Central neurocytoma/extraventricular neurocytoma is a central nervous system (CNS) tumor composed of uniform round cells with neuronal differentiation. The typical lesions of central neurocytoma/extraventricular neurocytoma are at the interventricular foramen of the lateral ventricles (central neurocytoma) or brain parenchyma (extraventricular neurocytoma). Mature teratoma is a benign germ cell tumor commonly found in young women. Herein, we report a 24-year-old female with neurocytoma in a mature teratoma of the right ovary. The histological examinations showed mature epidermis, skin appendages, adipose and bone tissues in the tumor; microscopic foci of immature cartilage tissues were also found in some parts. In addition, massive solid sheets and uniform round tumor cells were found in the neuroectodermal tissues, with the formation of neuropil-like islands. Immunohistochemical examinations showed that the tumor cells were synaptophysin- and NeuN-positive but GFAP-negative. Based on these findings, the woman was diagnosed with neurocytoma arising from mature ovary teratoma, with microscopic foci of immature cartilage tissues. This is the fourth case report of neurocytoma outside the CNS to date.

Behavioral disorders as unusual presentation of pediatric extraventricular neurocytoma: report on two cases and review of the literature

BACKGROUND

Extraventricular neurocytomas (EVNs) are rare parenchymal brain tumors, distinct from central neurocytomas that are typically located within the supratentorial ventricular system. Seizures and headache represent the most common symptoms of extraventricular neurocytomas in the cerebral hemisphere both in adult and pediatric population.

CASE PRESENTATION

We describe two cases of pediatric EVN with clinical onset characterized by behavioral and attention deficit/ hyperactivity disorders. The association between behavioral/attention disorders in childhood and the presence of a frontal neurocytoma has never been described before. Furthermore, inappropriate levels of inattention, hyperactivity and impulsivity are common among the neurobehavioral and developmental disorders in childhood. We reviewed 43 pediatric cases of extraventricular neurocytoma included in the PubMed database and their clinical presentation, and we never found this unusual relationship.

CONCLUSION

In childhood, the attention/hyperactivity disorders seem to be often over-diagnosed. When these deficits are more subtle and do not well-fit in a specific neurocognitive disorder, the clinicians should have a suspicion that they might mask the clinical features of a frontal lesion. This paper is focused on the clinical presentation of the extraventricular neurocytoma and the possible organic etiology of an attention and hyperactivity deficit.

Central neurocytoma: establishment of the disease entity

The establishment and identification of central neurocytoma as a distinct disease entity are invaluable in catalyzing investigations of neuronal differentiation in central nervous system tumors. The discovery of neuronal differentiation in neuroepithelial tumors has been extended to extraventricular tumors and potentially to various glial tumors undergoing neuronal differentiation. Understanding the disease spectrum of neuronal and mixed neuronal-glial tumors is important for deciphering the mechanism of gliomagenesis.

Extraventricular neurocytoma, a comprehensive review

AIMS AND OBJECTIVE

Extra ventricular neurocytoms (EVN) are a rare parenchymal brain tumour distinct from central neurocytomas. This review attempts to analyze a series of seven cases of EVN from a single institute against the background of available literature.

METHOD

Retrospective analysis of the clinical manifestation, pathological features, imaging findings, microsurgical treatment effectiveness and progression free survival of seven cases of EVN operated between 2000-2012.

RESULTS

The study group included five females and two males in the age group 7-65 years (mean 30.71 yrs). The distribution of the lesion was as follows Lobar 4, Cerebellum 1, Pineal 1, spinal 1. The duration of clinical symptoms ranged from three months to seven years and the presentation was site and size specific. Cystic Changes (71 %), perilesional oedema (57 %) and heterogeneous contrast enhancement (85.7 %), and calcification (42 %) were a few distinct imaging characteristics. Increased perfusion correlated with atypical histology in two patients. Surgical resection remains the main management strategy for longer outcome and patients with STR + RT and GTR had comparable follow-up. Extremes of age and atypical histological features were adverse prognostic factors.

CONCLUSION

EVN are rare tumors with either glial or neuronal differentiation or a potential for atypical changes. Both, GTR and STR combined with RT, offer reasonably good outcome with overall comparable survival. The available literature of EVN is limited, larger series with long term follow-ups are needed to dictate the management protocol. The role of adjuvant therapy is still debatable and needs further validation.

Extraventricular neurocytoma in pediatric populations: A case report and review of the literature

Extraventricular neurocytomas (EVNs) are rare neuronal tumors included in the definition of neoplasms in the 2007 World Health Organization classification of tumors of the central nervous system. Although a small case series of EVNs in adults has been previously reported, EVNs in pediatric populations are extremely rare. The current case report presents the clinicopathological features of an EVN in a 2-year-old female who presented with nausea and vomiting that had lasted for five days. In addition, an analysis of the imaging features, histology, treatment and prognosis of these reported rare lesions is presented. Immunohistochemically, EVNs are characterized by the robust expression of synaptophysin, but with a lack of oligodendrocyte transcription factor 2, isocitrate dehydrogenase enzyme isoform 1 (IDH1) R132/IDH2 R172 mutations and p53 immunoexpression. The treatment for EVNs in pediatric and adult populations is gross total resection, with post-operative radiation reserved for subtotal resection or recurrent disease. In addition, drop metastasis must be carefully avoided.

Computed tomography and magnetic resonance features of extraventricular neurocytoma: a study of eight cases

AIM

To present the neuroradiological and clinical findings of extraventricular (central) neurocytomas (EVNs) to increase awareness of this entity.

MATERIALS AND METHODS

The computed tomography (CT; n = 6), magnetic resonance imaging (MRI; n = 8), and clinical presentations of eight patients with pathologically documented EVN were retrospectively analysed.

RESULTS

Most tumours were well circumscribed and occurred in young adults. Six tumours were solid or solid-cystic, five of these showed contrast enhancement and three contained calcifications. Multiple small cysts were present in one solid mass and had a "soap bubble" or spongy appearance on MRI. Two other tumours were predominantly cystic; these demonstrated slight contrast enhancement, which contained calcifications. Of the six cases assessed using CT, three showed predominantly hyperdensity and three showed hypodensity, with a mean attenuation value of 75 HU. At MRI, eight masses were isointense (n = 4) or hypointense (n = 4) to grey matter on T1-weighted images and hyperintense (n = 6), isointense (n = 1), or hypointense (n = 1) on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. Signal voids were visible in two cases. Four tumours had mild or moderate peritumoural oedema.

CONCLUSION

EVN is a rare neoplasm that can have significant overlap in imaging appearance with other primary brain neoplasms; therefore, it is difficult to make an accurate preoperative diagnosis. However, EVN should be considered in the differential diagnosis when a large cerebral parenchymal mass with cystic change and calcification is encountered in younger patients.

Surgical management of intraventricular central neurocytoma: 92 cases

OBJECTIVE

To analyse the clinical characteristics of intraventricular central neurocytomas and gain a better understanding of the surgical management and treatment strategies.

METHODS

A total of 92 cases of intraventricular central neurocytomas with initial treatment using surgical resection were studied retrospectively.

RESULTS

Among 48 male and 44 female patients, 65 underwent gross total resection and 27 underwent subtotal resection. Transcortical or transcallosal approaches were performed, and there was no significant difference between the two approaches in terms of effects and complications. Tumours with calcification or adhesion had a significant lower gross total resection rate. Three patients died after surgery. During follow-up, 55 patients underwent postoperative radiotherapy and four patients had a recurrence of the tumour.

CONCLUSION

Central neurocytomas mostly occur in the lateral ventricle system near the foramen of Monro. Therefore, total resection is the best treatment. Two surgical approaches are possible as treatment. Calcifications or adhesions affect the gross total resection of the tumour. Radiation therapy or radiosurgery therapy can be chosen as a salvage treatment in case of recurrence.

Infiltrative brainstem and cerebellar neurocytoma

Neurocytomas are typically intraventricular in location, and extraventricular neurocytomas are uncommon. The authors report the unique case of a 15-year-old girl who was found to have a low-grade neurocytoma infiltrating the brainstem and cerebellum and spreading along the CSF pathways to the lateral and third ventricles. The patient underwent endoscopic third ventriculostomy to treat associated hydrocephalus, and biopsy specimens from intraventricular tumor nodules were obtained. Because of the low-grade pathology, the fact that the lesion was not amenable to resection, and the extensive radiation field required for radiation therapy, she has been treated conservatively with close follow-up. Over the course of almost 4 years since diagnosis, no additional treatment has been required. Neurocytoma with widespread infiltration of the brainstem and cerebellum has not been previously reported.

Atypia predicting prognosis for intracranial extraventricular neurocytomas

OBJECT

The literature, at present, provides limited information about extraventricular neurocytomas (EVNs) and is almost exclusively composed of case reports or small case series. Treatment for EVNs has largely been guided by results from central neurocytoma outcome studies. The authors present an analysis of all reported intracranial EVN cases to establish if tumor histopathological features can substratify EVN into groups with differing prognosis and help guide treatment decisions.

METHODS

The authors identified studies reporting histology, treatment modality, and outcomes for patients with intracranial EVN. The rates of recurrence and survival for patients were compared using Kaplan-Meier analysis. Atypical tumors, defined by MIB-1 labeling index exceeding 3% or atypical histological features, were compared with typical tumors, and patients 50 years of age or older were compared with those younger than 50 years of age.

RESULTS

Eighty-five patients met the inclusion criteria, and 27% of them had an atypical histology. Typical EVNs had a better prognosis than atypical EVNs after primary treatment, with a 5-year recurrence rate of 36% compared with 68% (p < 0.001), and a 5-year mortality rate of 4% compared with 44%, respectively (p < 0.001). Age younger 50 years was associated with a better prognosis than age equal to or greater than 50 years, with a 5-year recurrence rate of 33% and 74%, respectively (p < 0.001), and a 5-year mortality rate of 4% and 52%, respectively (p < 0.001). Multivariate analysis demonstrated that atypical EVNs carried significantly increased risk for recurrence (hazard ratio [HR] 4.91, p < 0.001) and death (HR 22.91, p < 0.01). Gross-total resection was superior to subtotal resection (STR) alone in tumor control rates for typical EVNs (95% and 68%, p < 0.05), and there was a trend for adjuvant external-beam radiotherapy to benefit STR. There was suggestion of similar trends in patients with atypical EVNs.

CONCLUSIONS

There are at least 2 distinct histological subtypes of EVN, with different prognostic significances. Atypia or MIB-1 labeling index greater than 3% is a significant predictor of poor prognosis for EVNs. Complete resection or more aggressive attempts at providing adjuvant therapy following STR appear to improve the prognosis for patients with EVNs. Although the authors' results are informative, there are limitations to their analysis. Given the relatively modest total number of cases reported, as well as the nature of the disaggregated analysis, the authors were not able to use formal meta-analytical methods to limit the impact of between center heterogeneity. Additionally, they were not able to control for individual differences in data analysis and presentation across the different studies included in their analysis.

Skull base neurocytoma: case report and review of the literature of extraventricular neurocytomas

We report a rare skull base neurocytoma. A 44-year-old female with a history of focal seizure and progressive right-sided weakness sought treatment at an outside institution, where she underwent total resection of a "left medial sphenoid wing paraganglioma" in 1984. In 1995 after experiencing intense left-sided headaches for 3 weeks, the patient presented to our institution. Magnetic resonance imaging revealed a large local recurrence. She had deficits dating to her initial surgery, including moderate right-sided hemiparesis, complete left ophthalmoplegia, and left facial numbness.The patient underwent a craniotomy with extensive removal of the involved sphenoid bone and a subtotal resection of the tumor. Neurocytoma was diagnosed based on strong immunohistochemical staining for synaptophysin and no reactivity for glial fibrillary acidic protein. Postoperatively, her headaches resolved completely and her neurologic status remained at baseline. The residual tumor was treated with radiation therapy. After 5 years, she remains clinically and radiographically stable.Although typically located adjacent to the foramen of Monro, neurocytomas have now been reported in almost every subcompartment of the craniospinal axis. Finding neurocytomas in extraventricular locations may require revisiting the current theory that subependymal progenitor cells are the cells of origin for these tumors.

Gamma knife radiosurgery for cranial neurocytomas

Gamma-knife surgery may be an effective alternative for treatment of central neurocytomas owing to its relative safety compared with conventional radiotherapy. In this paper we present results of gamma-knife treatment (GKS) of residual or recurrent neurocytomas. Twenty-two patients (14 female, 8 male) with recurrent or residual neurocytomas who underwent GKS were included. Diagnosis was based on histological findings. The proliferative potential of the tumors was examined by immunostaining with MIB-1 antibody, which is specific for detection of Ki-67 antigen. Tumor volume was determined by using post-gadolinium magnetic resonance images. After GKS treatment, MR imaging was scheduled at three-month intervals in the first year, at six months intervals in the second year, and yearly thereafter. Histopathological diagnoses were: 18 cases of central neurocytomas, two liponeurocytomas, one cerebral neurocytoma and one cerebellar neurocytoma. The MIB1 labeling index (LI) varied from 0 to 5.7%. Marked reduction in tumor volume was seen in 15 patients. In six patients, the tumor volume remained unchanged, and progression was observed for one patient. No complications because of GKS were noted. Shrinking effect on tumor volume increased with increasing duration of follow-up. On the other hand, high MIB labeling index did not seem to have an effect on tumor response to GKS treatment. Findings of this study suggest that GKS is an effective and safe treatment alternative for residual or recurrent neurocytomas. However, its effectiveness should be confirmed with larger studies.

Extraaxial neurocytoma in the skull base

Extraventricular neurocytoma is an uncommon neuronal tumor, located outside the cerebral ventricles, which shows histological features similar to those of central neurocytoma. Most extraventricular neurocytomas are situated in the intraaxial regions of the central nervous system. We report a rare case of an extraaxial neurocytoma in the sphenocavernous-petroclival region that was successfully treated by radiation therapy following partial removal and pathological evaluation of the tumor.

Neurocytoma of the cerebellum

Background:

Neurocytomas are benign central nervous system tumor composed of small cells with characteristics of neuronal differentiation; they are usually located in the supratentorial periventricular region, in close relation to the septum pellucidum and the foramen of Monro.

Case Description:

Herein we report a rare case of a neurocytoma located in the cerebellar hemisphere. To date there are only four such reported cases.

Conclusion:

Neurocytomas should be considered in the differential diagnosis of mass lesions in the cerebellum.

Temporo-mesial extraventricular neurocytoma and cortical dysplasia in focal temporal lobe epilepsy

We describe a 17-year-old boy with a left extraventricular temporo-mesial neurocytoma associated with cortical dysplasia causing focal pharmacoresistant temporal lobe epilepsy. He presented with a long history of medically refractory, temporal complex partial seizures. MRI showed a left temporo-mesial lesion suspect to be a low-grade tumor. Based on the pre-operative non-invasive neurophysiological studies, the patient underwent a left tailored temporal antero-mesial resection. Histopathological examination showed an extraventricular neurocytoma associated with architectural dysplasia (Type 1a) of the temporal pole. The patient was seizure-free at 2 years follow-up. Extraventricular neurocytomas must be considered in the differential diagnosis of the plethora of low-grade tumors associated with focal epilepsy that typically involve the temporal lobe, and are frequently associated with focal cortical dysplasia.

Extraventricular neurocytoma in a child: case report and review of the literature

Neurocytomas are relatively rare central nervous system tumors first described in intraventricular sites but increasingly recognized in the brain and spinal cord parenchyma. Herewith, we report a case of a 3-year-old girl with generalized seizures. Computed tomography and magnetic resonance imaging revealed a lesion in the left frontal lobe. Angiography showed minimal vascularity. The tumor was totally excised. Histopathologic examination demonstrated an extraventricular neurocytoma. On follow-up magnetic resonance imaging after 1 year, no evidence of tumor recurrence was noted. Cerebral neurocytomas are histologically low-grade tumors and radical surgery is curative; they should be included in the differential diagnosis of cerebral tumors in children.

Coincidence of central neurocytoma and multiple glioblastomas: a rare case report

Coincidence of parenchymal primary brain tumors of different histogenesis is extremely rare. To the best of our knowledge, the present case of simultaneous appearance of a central neurocytoma and multiple glioblastomas is the first to be reported. Multiple intraaxial brain neoplasms were disclosed in a 39-year-old man and were surgically resected. Histological diagnosis of the tumor located in the right lateral ventricle was central neurocytoma whereas two tumors of the left temporal lobe were glioblastomas. The latter were located in close proximity to the subarachnoid space, had atypical radiological appearance, and were slightly positive for synaptophysin and neurofilament protein. It can be speculated that both malignant neoplasms were, in fact, dedifferentiated central neurocytoma, which developed from distant tumor deposits. This case seems to be in agreement with the hypothesis that central neurocytoma arises from the progenitor cells with potential for both neuronal and glial differentiation. Better understanding of histogenesis of this tumor is definitely needed.

Endoscopic removal of a central neurocytoma from the posterior third ventricle

Central neurocytoma is a rare benign tumor that most commonly arises within the ventricular system of young adults. Its occurrence in the posterior third ventricle is one of the least reported presentations. These tumors are usually treated by a combination of either biopsy or open surgical resection, often followed by radiation (Gamma knife or Novalis) with or without chemotherapy. A 37-year-old woman with a posterior third ventricle neurocytoma presented with acute signs of aqueductal stenosis. The patient underwent endoscopic assisted gross total resection of the tumor with the aid of intraoperative laser followed by standard third ventriculostomy; no further treatment was required. The patient did not develop any subsequent neurological deficit. A 36-month follow-up was still consistent with a normal neurological examination. Serial post-operative MRIs show neither residual nor recurrent tumor. Thus, posterior third ventricle central neurocytomas are relatively benign tumors that can be successfully removed using a minimally invasive approach, thereby avoiding both the morbidity related to conventional open craniotomy and the potential toxicity of any adjuvant treatment.

Surgical neuropathology update: a review of changes introduced by the WHO classification of tumours of the central nervous system, 4th edition

CONTEXT

The World Health Organization (WHO) recently published its 4th edition of the classification of tumors of the central nervous system, incorporating a substantial number of important changes to the previous version (WHO 2000). The new WHO classification introduces 7 changes in the grading of central nervous system neoplasms, ranging in significance from minor to major, in categories of anaplastic oligoastrocytomas, meningiomas, choroid plexus tumors, pineal parenchymal tumors, ganglioglioma, cerebellar liponeurocytoma, and hemangiopericytomas. The 4th edition also introduces 10 newly codified entities, variants, and patterns, as well as 1 new genetic syndrome. A number of established brain tumors are reorganized, including medulloblastomas and primitive neuroectodermal tumors, in an attempt to more closely align classification with current understanding of central nervous system neoplasia.

OBJECTIVE

To summarize and discuss the most significant updates in the 4th edition for the practicing surgical pathologist, including (1) changes in grading among established entities; (2) newly codified tumor entities, variants, patterns, and syndromes; and (3) changes in the classification of existing brain tumors.

DATA SOURCES

The primary source for this review is the WHO Classification of Tumours of the Central Nervous System, 4th edition. Other important sources include the 3rd edition of this book and the primary literature that supported changes in the 4th edition.

CONCLUSIONS

The new edition of the WHO blue book reflects advancements in the understanding of brain tumors in terms of classification, grading, and new entities. The changes introduced are substantial and will have an impact on the practice of general surgical pathologists and neuropathologists.

Neurocytoma: a comprehensive review

Central neurocytomas (CN) are uncommon tumors of the central nervous system, most descriptions of which available in the literature are in the form of isolated case reports and small series. Owing to this rare incidence, diagnosis and management of this neoplasm remain controversial. Usually, these tumors affect lateral ventricles of young adults and display characteristic neuroimaging and histomorphologic findings. Neurocytomas often mimic oligodendrogliomas when confirmation of diagnosis rests on immunohistochemistry, ultrastructure, and genetic studies. Extraventricular neurocytomas, situated entirely within the brain parenchyma and spinal cord, have also been reported. Typically, CN are associated with a favorable outcome although cases with more aggressive clinical course with recurrences are not unknown. MIB-1 labeling index (LI) of >2% often heralds poor prognosis and tumour recurrence. Safe maximal resection is presently considered the ideal therapeutic option, with best long-term prognosis in terms of local control and survival. The role of adjuvant radiotherapy apparently seems to benefit patients with incomplete resection and in atypical neurocytoma. Utility of other therapeutic regimen, however, remains shrouded in controversy. Epidemiology, histogenesis, clinical profile, histology, neuroimaging and therapeutic modalities of neurocytomas have been comprehensively reviewed, with special emphasis on CN and extraventricular neurocytomas and their atypical counterparts.

Pontine Atypical Neurocytoma: Case Report

OBJECTIVE AND IMPORTANCE:

Neurocytomas are typically located within the supratentorial ventricular system. Extraventricular neurocytomas are very rare, and this is only the second reported case of a pontine neurocytoma. We discuss the clinical presentation, histology, and treatment of these rare tumors.

CLINICAL PRESENTATION:

A 58-year-old man presented with a 4-month history of headache and unilateral facial and distal extremity paresthesia. Magnetic resonance imaging (MRI) scans demonstrated a 2.6 × 2.2-cm ring-enhancing cystic mass in the right pons.

INTERVENTION:

MRI-guided stereotactic biopsy yielded a diagnosis of atypical neurocytoma. Because of the location and malignant histological features of the tumor, the patient was initially treated with external beam radiation therapy. Several months later, MRI scans demonstrated tumor progression. The patient then underwent three rounds of temozolomide chemotherapy, during and after which his symptoms worsened. Aggressive subtotal resection of the tumor was achieved via a right suboccipital craniectomy.

CONCLUSION:

Twenty-eight months postoperatively, the patient is symptom free, and MRI scans demonstrate no evidence of residual or recurrent tumor.

Central neurocytoma: a novel appraisal of a polymorphic pathology. Our experience and a review of the literature

Central neurocytoma should be considered in the differential diagnosis of intraventricular tumours. The records of 20 patients operated on between 1975 and 2000 for central neurocytoma were retrospectively reviewed, and the histological gradings and clinical outcomes were compared. On the basis of our previous cases, in the latter five of this series, the following therapeutic protocol was adopted. In those cases in which total removal was achieved, no further treatment was given if the MIB-1 index was <4%; vice versa, if it was >4%, a course of conformational radiotherapy was delivered. In subtotally removed cases, radiosurgery with linac was also performed (median dose 20 Gy) as well as conformational radiotherapy whenever there was a recurrence of the lesion (median dose 45 Gy). In cases in which there was only partial cytoreduction, conformational radiotherapy was administered with the adjunct of polychemotherapy if the MIB-1 was >4%. Twenty patients were surgically treated: 11 men and nine women, with an average age of 26 years (range 17 years to 42 years).Total, subtotal and partial removals were achieved in, respectively, ten, three and seven cases. At average follow-up of 7 years, 16 patients had been cured, had significantly improved or were at least stable [Karnofsky performance status score (KPS)] >70 or more)]. On the other hand, four patients had worsened; of these, two had died and two had a KPS=50 and an unfavourable prognosis. The presence of histological atypia has proved to be a significantly negative risk factor for survival (P=0.02) while an MIB score >4% was significantly correlated with an unfavourable outcome (death or worsening of neurological status). The "atypical" neurocytoma seems to be a distinct entity, with a less favourable prognosis and a higher tendency to recur.

March 2004: a 24-year-old woman with bifrontal headaches

A 24-year-old woman with bifrontal headaches was found to have a well-circumscribed lesion in the frontal lobe subcortical white matter. Microscopic examination showed clusters of small round cells separated by hypocellular neuropil-like areas, and a distinct border between tumor and surrounding white matter. Synaptophysin was diffusely positive in neuropil-like areas, and many tumor cells expressed NeuN. Based on these findings, a diagnosis of "extraventricular neurocytoma" was made. A double-label immunofluorescence stain was performed with NeuN and Ki-67 antibodies to determine if NeuN+ cells remained in the mitotic cycle. No colocalization of these markers was found, thus supporting the hypothesis that neuronal differentiation (as marked by NeuN expression) is incompatible with continued proliferation of tumor cells, as well as normal neurons.

Intraventricular neurocytomas

The literature to date on the treatment of CNC reflects an evolution of clinical practice in neurooncology. The advent of sophisticated tools, such as MRS and molecular pathology, has facilitated more efficient diagnosis of CNC. Decreased morbidity associated with surgical intervention has resulted in better outcomes in patients undergoing resection of CNC. Prospective monitoring of treated patients with MRI coupled with judicious use of radiosurgery will likely further decrease treatment-related morbidity.

Peritoneal dissemination from central neurocytoma: case report

OBJECTIVE

Central neurocytoma is a low grade tumor of neuroglial origin and a relatively new histological entity. Only a few cases have been reported and its biological behavior is still uncertain. Some cases have shown an aggressive behavior (local recurrence, malignant dedifferentiation or CSF dissemination) and challenged the initial view of its relative benignity. A case of central neurocytoma with peritoneal dissemination is presented.

CASE

A six years-old boy with recurrent neurocytoma of III ventricle and left thalamus showed fast growth of tumor rest and ascites three and a half years after subtotal removal of the lesion. Tumor cells were identified in the ascitic fluid and implanted in the peritoneum. Chemotherapy was initiated immediately after diagnosis of peritoneal dissemination (etoposide, carboplatin, doxorubicin and cyclophosphamide). The patient developed metabolic imbalance and respiratory failure due to rapid formation of ascitic fluid and died 3 days after the diagnosis of peritoneal dissemination was established.

CONCLUSION

Central neurocytoma is a low grade tumor with low values of the proliferative index in the majority of cases. In spite of that, some tumors may present a very aggressive behavior and extraneural dissemination. Evaluation of proliferative index may be a guideline parameter for planning adjuvant therapies after surgical treatment in selected cases. Extraneural dissemination may occur in some cases specially in patients with ventriculoperitoneal shunt.

Tratamiento del neurocitoma central. Experiencia en nuestro centro

Central neurocytomas are classically considered as a rare, intraventricular benign tumours with neuronal differentiation derived from precursor cells of subventricular matrix. However some patients with neoplasms with histologic atypia and elevated proliferation potential may have a poor outcome. Treatment of choice is complete surgical excision. Adjuvant therapy is reserved for patients with residual or recurrent lesions including reoperation, radiotherapy or chemotherapy. We review our experience with the treatment of this neoplasm. Five patients with an intraventricular mass studied with magnetic resonance imaging underwent craniotomy for tumour resection. All cases were reviewed retrospectively. Histopathological analysis confirmed central neurocytoma in all cases. Proliferation index was assessed by Ki-67 immunohistochemistry. Complete radiological tumor resection through transcortical approach was achieved in all except one patient. In this case adjuvant therapy with radiosurgery was given with important reduction in tumor size. All the tumours had a proliferation index below 2% except one with 5%. Follow-up in four patients ranged from 12 to 36 months. There were no tumour recurrences in this period. Complete surgical excision of central neurocytoma provides better local control and survival compared with other treatments. Radiosurgery as adjuvant therapy in incomplete resections may eliminate the need of reoperation and avoid long-term side effects from conventional radiotherapy.

A papillary glioneuronal tumor arising in an elderly woman: a case report

The papillary glioneuronal tumor (PGNT) was first reported by Komori et al. as a type of mixed neuronal-glial tumor. It is characterized by pseudopapillary structures, composed of hyaline vessels and outsheathing glial cells, and by the proliferation of neurocytic cells admixed with ganglioid and ganglion cells. Although it is most common in young adults, it can occur in the elderly. We report a case in a 75-year-old woman, the oldest reported person with PGNT described.

Genetic differences between neurocytoma and dysembryoplastic neuroepithelial tumor and oligodendroglial tumors

OBJECT

Because of their histological similarities, it is occasionally difficult to differentiate neurocytoma and dysembryoplastic neuroepithelial tumor (DNT) from oligodendroglial tumors. This study was conducted to investigate genetic differences among these tumor types in terms of loss of heterozygosity on chromosomes 1p and 19q, and p53 gene mutation.

METHODS

A total of 24 tumors were analyzed, consisting of eight central neurocytomas, three DNTs, seven oligodendrogliomas, four oligoastrocytomas, and two undetermined extraventricular tumors with neurocytoma features (ETNFs). Allelic loss was determined using microsatellite markers that cover the common deletions on chromosomes 1p and 19q in oligodendrogliomas. A p53 gene mutation was identified using polymerase chain reaction-single-strand conformation polymorphism analysis and subsequent direct sequencing. Immunohistochemical studies with synaptophysin and electron microscopy investigations were also conducted. Allelic loss on 1p and 19q was detected in six oligodendrogliomas (86%) and in three oligoastrocytomas (75%), but in none of the central neurocytomas or DNTs. A p53 missense mutation was detected at codon 161 (GCC-->ACC, Ala-->Thr) in only one oligoastrocytoma without allelic loss. Synaptophysin was expressed in all central neurocytomas and DNTs, in three oligodendrogliomas (43%), and in three oligoastrocytomas (75%). Of the ETNFs, one demonstrated synaptophysin expression and neural ultrastructures but lacked genetic alterations, whereas the other showed allelic loss on 1p and 19q but was negative immunohistochemically and ultrastructurally. The former was diagnosed as a potential intraparenchymal neurocytoma and the latter as an oligodendroglioma.

CONCLUSIONS

Despite histological similarities, central neurocytomas and DNTs are genetically distinct from oligodendroglial tumors. Examination for allelic loss on 1p and 19q and for p53 mutation can be useful for making this distinction.

Stereotactic radiosurgery for residual neurocytoma. Report of four cases

The purpose of this report was to review the results of stereotactic radiosurgery in the management of patients with residual neurocytomas after initial resection or biopsy procedures. Four patients underwent stereotactic radiosurgery for histologically proven neurocytoma. Clinical and imaging studies were performed to evaluate the response to treatment. Radiosurgery was performed to deliver doses to the tumor margin of 14, 15, 16, and 20 Gy, depending on tumor volume and proximity to critical adjacent structures. More than 3 years later, imaging studies revealed significant reductions in tumor size. No new neurological deficits were identified at 53, 50, 42, and 38 months of follow up. The authors' initial experience shows that stereotactic radiosurgery appears to be an effective treatment for neurocytoma.

Extraventricular neurocytomas: pathologic features and clinical outcome

Neurocytic neoplasms usually arise within the lateral ventricles, generally as circumscribed, slowly growing masses curable by total resection. Both subtotal resection and histologic atypia are associated with an increased risk of recurrence. In contrast, neurocytic neoplasms situated within brain parenchyma, so-called "extraventricular neurocytomas" (EVNs), are not as well characterized. The relationships between histologic features and extent of resection versus clinical behavior have not been defined. We evaluated pathologic features, clinical data, and neuroimaging of 35 examples. The tumors occurred in 18 males and 17 females, age 5-76 years (median 34 years). All tumors involved the cerebrum. On imaging, EVNs were solitary, variably contrast-enhancing, and often (57%) cystic. Tumor cells were arranged in sheets, clusters, ribbons, or rosettes, in association with fine neuropil dispersed in broad zones that separated cell aggregates. Ganglion cell differentiation was seen in 66%. All tumors showed strong synaptophysin immunoreactivity. Despite the lack of apparent astrocytes in hematoxylin and eosin-stained sections, focal glial fibrillary acidic protein reactivity was seen in 46%. Eleven EVNs were designated "atypical" based on the presence of necrosis, vascular proliferation, or elevated mitotic activity (> or = 3 mitoses/10 high power fields). Nineteen tumors were subtotally resected or biopsied, whereas 14 were totally resected grossly. Seventeen patients underwent radiotherapy (mean 55 Gy). In 30 cases with follow-up, 10 tumors recurred, 3 causing death at 6, 14, and 43 months. All 10 recurrences followed subtotal resection. No totally resected tumors recurred. Thus, the majority of EVNs are well differentiated and appear unlikely to recur after gross total resection. Subtotal resection, atypical histologic features, and high cell proliferation rates correlate with recurrence.