Extraventricular neurocytomas: pathologic features and clinical outcome

Pediatric atypical extraventricular neurocytoma: Clinical features and survival outcomes

BACKGROUND

Extraventricular neurocytoma (EVN) in children is an extremely rare encountered tumor. Little information is available about the treatment and prognosis of this rare disease in children. This study was undertaken to elucidate the clinical-radiological characteristics and treatment outcomes of pediatric patients with atypical EVN.

METHODS

A retrospective review of patients' demographic features, treatment modalities, and outcomes in our institution from January 2011 to December 2019 was conducted.

RESULTS

Seven consecutive children harboring atypical EVN in our center were included, with a male predominance (n = 5, 71.4%) and a mean age of 11.8 ± 4.9 years (range: 2-18 years). The lesions mainly involved the frontal (n = 4, 57.1%) and temporal lobes (n = 4, 57.1%). Gross total resection (GTR) was achieved in 6 patients (85.7%), and subtotal resection (STR) was achieved in the remaining patient (14.3%). All lesions demonstrated a high Ki-67 index (≧5%) and atypical features pathologically. Five patients (71.4%) received radiotherapy and/or chemotherapy after surgery. During follow-up, 5 patients (71.4%) experienced lesion progression, and 2 (14.3%) of them died. The median progression-free survival was 48 months.

CONCLUSIONS

The prognosis of pediatric patients with atypical EVN was dismal after aggressive treatment. Most tumors progressed, and this progression was positively correlated with the Ki-67 index. Surgical excision is the main treatment modality for atypical EVN, and radiation/chemotherapy should also be introduced after surgery.

Cytopathology of glioneuronal and neuronal tumours with histological correlations

Glioneuronal and neuronal tumours constitute a diverse group of tumours that feature neuronal differentiation. In mixed glioneuronal tumours, a glial component is present in addition to the neuronal component. With a few exceptions (eg diffuse leptomeningeal glioneuronal tumour) they are well-circumscribed and slow-growing tumours, which is why their prognosis is intrinsically favourable after gross total resection. Rendering an intraoperative diagnosis of glioneuronal/neuronal tumour is therefore important-neurosurgeons should remove them to prevent the persistence of clinical symptoms and/or recurrence. In this context, cytopathological examination can be especially useful for assessing cellular details when frozen section artefacts render poor-quality preparations, as is the case for this group of tumours, which are frequently mistaken for infiltrating gliomas (eg diffuse astrocytoma infiltrating grey matter, oligodendroglioma) on frozen section slides. The aim of this article is to review the cytomorphological features of glioneuronal and neuronal tumours according to the 2021 World Health Organization classification of central nervous system tumours, 5th edition. Additionally, since interpretation in intraoperative cytology relies on intuiting tissue patterns from cytology preparations, representative histological figures of all discussed entities have been included. Clues for specific diagnoses and the primary diagnostic problems encountered during intraoperative procedures are also discussed.

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.

The role of single fraction Gamma Knife radiosurgery for intraventricular central neurocytomas and the utility of F-18 fluroethyltyrosine: two case reports

BACKGROUND

Primary treatment of central neurocytomas is surgical resection. Gamma Knife surgery is considered a valuable therapeutic option in case of residual (after subtotal resection) or recurrent central neurocytomas. Here, we focused on the role of F-18 fluroethyltyrosine as a marker to document tumor progression after initial resection, in the context of an atypical central neurocytoma. We also describe MIB-1's role in evaluating therapeutic decision-making.

CASE PRESENTATION

Two patients with central neurocytomas were treated by Gamma Knife surgery in our center. The first case (31-year-old Caucasian male) had atypical central neurocytoma. Four and a half years after surgical resection, magnetic resonance imaging and F-18 fluroethyltyrosine documented clear progression of residual central neurocytoma, further treated by Gamma Knife surgery (18 Gy at 50%, target volume 1.4 cc, and prescription isodose volume 1.8 cc). The initial post-Gamma Knife surgery clinical course was uneventful, with progressive volumetric reduction of residual tumor up to 4.5 years, when out-of-field recurrence was suspected and confirmed by local F-18 fluroethyltyrosine hyperactivity. Second single-fraction Gamma Knife surgery was performed (18 Gy at 50%, target volume 0.49 cc, prescription isodose volume 0.72 cc). The second (32-year-old Caucasian female) had previous subtotal resection and typical central neurocytoma. Seven years later, she had residual tumor progression. Single-fraction Gamma Knife surgery was performed (16 Gy at 50% isodose line, target volume 1.7 cc, and prescription isodose volume 2.5 cc). Last follow-up showed tumor volume reduction. Follow-up magnetic resonance imaging showed important volumetric reduction of both treated lesions.

CONCLUSIONS

In atypical central neurocytomas, F-18 fluroethyltyrosine could be used as postoperative examination to detect small tumor remnants, follow-up evaluation following the Gamma Knife surgery or, in select cases, following surgical resection. The role of MIB-1 is important in therapeutic decision-making, as tumors with MIB-1 exceeding 2% are characterized by more aggressive clinical course. Single-fraction Gamma Knife surgery remains a valuable therapeutic option for postoperative residual atypical central neurocytomas and central neurocytoma recurrences.

Extraventricular Neurocytoma: Clinical Investigation of Heterogenous Prognosis

BACKGROUND

Extraventricular neurocytoma (EVN) is an extremely rare neuronal neoplasm that arises outside the ventricle. The clinical implication of the heterogenous prognosis of this rare tumor has not yet been clarified. Herein, we analyzed our institutional series of EVN.

METHODS

A total of eight consecutive cases were enrolled and investigated. The prognosis of EVN was analyzed and compared to that of central neurocytoma (CN).

RESULTS

There were two male and six female patients, and the median age was 36.5 years. The median tumor size was 38 mm, and the most common location of the tumor was the frontal lobe (3, 37.5%), followed by the parietal and temporal lobes. In brain imaging, four (50%) tumors showed peritumoral edema and three (37.5%) tumors showed calcification. All patients underwent gross total resection, and two (25%) underwent adjuvant radiotherapy. The 5-year overall survival (OS) was 55.6%, and the 2-year progression-free survival (PFS) was 42.9%. The OS and PFS of EVN were poor compared to those of CN. Although EVN is a single disease entity, individual patients showed varying prognosis. One patient showed no recurrence during the 7-year follow-up period; however, another patient had a recurrence 4 months after surgery and died 2 years later.

CONCLUSION

EVN may be a heterogenous disease entity. Additional cases with long-term followup are needed to develop optimal management protocols.

Clinical Outcome After Microsurgical Resection of Central Neurocytoma: A Single-Centre Analysis of 15 Years

Objective: This study aimed to explore the immediate postoperative and long-term outcomes of central neurocytoma (CN) based on 15 years of experience in our institution.

Methods: This single-institution study collected data of 43 patients with CN who underwent surgery between 2005 and 2020. We reviewed data of clinical, immediate postoperative outcome, and long-term outcome of patients. More specifically, we divided complications into neurological and regional complications groups.

Results: Among the 43 patients with CN who underwent surgery, the transcortical (72.1%) or transcallosal (25.6%) approach was used. There were 18 patients (41.9%) who complained about postoperative neurological complications, including motor weakness (25.6%), memory deficit (18.6%), aphasia (7.0%), and seizure (4.7%). In addition, 18 patients suffered postoperative regional complications such as hydrocephalus (2.3%), hematoma (34.9%), infection (4.7%), and subcutaneous hydrops (2.3%). Only one-quarter of patients had suffered permanent surgical complications. The majority of patients recovered from the deficit and could turn back to normal life. There were no significant differences in the clinical outcomes between transcortical and transcallosal approaches. At a median follow-up of 61.8 months, the 5-year overall survival and progression-free survival were 87.0 and 74.0%, respectively. A multivariate Cox model analysis showed that the extent of resection was not related to progression-free survival. However, the extent of resection was significantly associated with overall survival, and gross total resection decreased the risk of death.

Conclusions: Patients with CN show favorable outcomes after surgery. The transcortical and transcallosal approaches have similar postoperative complication rates and long-term follow-up outcomes. In terms of long-term prognosis, maximal safety resection should be the first choice of CN.

A Clinicopathological and Molecular Analysis of Sellar/Suprasellar Neurocytoma Mimicking Pituitary Adenoma

OBJECTIVE

To investigate the clinicopathological characteristics, molecular genetic characteristics and prognosis of extraventricular neurocytoma located in the sellar/suprasellar region.

METHODS

Seven archived tumor samples derived from 4 patients with neurocytoma in the sellar/suprasellar region were collected from the First Affiliated Hospital of Fujian Medical University and the Affiliated Hospital of Qingdao University and retrospectively analyzed for clinical manifestations, imaging features, and histopathological features. Neuronal and pituitary biomarkers and molecular features were detected in these tumor tissues by immunohistochemistry and FISH or Sanger sequencing. The related literature was reviewed.

RESULTS

Three patients were female, while 1 was male, with an average age of 35.5 years (range: 27 to 45 years). The initial manifestations were mainly headache and blurred vision in both eyes. The first MRI examination showed marginally enhancing masses in the intrasellar or intra- to suprasellar region. The diagnosis of pituitary adenomas was based on imaging features. The levels of pituitary hormones were normal. Histologically, the tumor cells were arranged in a sheet-like, monotonous architecture and were uniform in size and shape with round to oval, exquisite and hyperchromatic nuclei, which densely packed close to one another and were separated only by a delicate neuropil background. There was no evident mitosis, necrosis or microvascular proliferation. The three cases of recurrent tumors were highly cellular and showed increased mitotic activity. Immunohistochemically, the tumor cells were positive for syn, CR, CgA, and vasopressin and were focally positive for NeuN, TTF-1, NF, CK8, vimentin, and S100 proteins. Other markers, including IDH1, BRAF VE1, Olig-2, and EMA, were negative. Pituitary transcription factors and anterior pituitary hormones were negative. Molecular genetic testing showed that the tumor cells lacked IDH gene mutations, LOH of 1p/19q, MYCN amplification, and EGFR alteration. With a median follow-up of 74.5 months (range 23 to 137 months), 3 patients relapsed at 11, 50, and 118 months after the initial surgery.

CONCLUSION

The morphological features and immunophenotypes of neurocytoma in the sellar/suprasellar region are similar to those of classic central neurocytoma. The prognosis is relatively good. Gross-subtotal resection and atypical subtype may be related to tumor recurrence.

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.

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 case of atypical spinal neurocytoma with EGFR mutation in a 12-year-old boy

Spinal neurocytoma (SN), although frequently reportedly as tumors of the central nervous system (CNS), are a distinct class of tumors, which can achieve a better prognosis following subtotal or gross total tumor resection. Nonetheless, even with the premise of successful treatment after tumor resection, poor prognosis after treatment due to the SN high proliferation index (typically known as atypical SN) have been reported. Over the past two decades, atypical SN was only reported in four pediatric cases, amidst the lingering controversy surrounding its postoperative adjuvant therapy. Thus, herein, we report a unique case of atypical SN with epidermal growth factor receptor (EGFR) amplification mutation in a 12-year-old boy. We, however, also highlighted the significance of radiotherapy and target therapy for patients with SN.

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.

Atypical Central Neurocytoma: An Investigation of Prognostic Factors

OBJECTIVE

Central neurocytoma is a rare nervous tissue benign neoplasm. A subset of central neurocytoma has unfamiliar aggressive tendency: so-called atypical central neurocytoma (ACN). This retrospective study aims to analyze the prognostic factors and the impact of various therapy tools on atypical central neurocytoma.

METHODS

Twenty-two patients diagnosed with ACN between January 2009 and March 2018 were included. Data collected included the patient's age, gender, tumor location, presenting symptoms, and treatment received. Patients were followed up to detect recurrence and to assess survival.

RESULTS

Median overall survival was 57 months, with a 5-year survival of 35%. Better survival was observed for patients <35 years old (66 vs. 47 months; P = 0.061) and patients with gross total resection over subtotal resection or biopsy (76, 45, and 22 months, respectively; P < 0.0001). Patients with a tumor located in the posterior half of the lateral ventricle had better survival, with no statistical significance (P = 0.053). Multivariate analysis showed prognostic significance with the extent of resection (P = 0.000). Progression-free survival ranged from 6 to 82 months, with a median value of 38 months and showed a significant relation with subtotal resection compared with biopsy (P = 0.006). Recurrence was less in patients who received radiotherapy and was statistically significant (P = 0.007).

CONCLUSIONS

Long-term survival is possible for patients with atypical central neurocytomas treated with surgery and postoperative radiation. Multivariate analysis confirmed that gross total resection was an independent prognostic factor for survival. Adjuvant radiotherapy reduces tumor recurrence, especially after incomplete surgery.

Glioneuronal tumors: clinicopathological findings and treatment options

Glioneuronal tumors are very rare CNS neoplasms that demonstrate neuronal differentiation, composed of mixed glial and neuronal cells. The majority of these lesions are low grade and their correct classification is crucial in order to avoid misidentification as ‘ordinary’ gliomas and prevent inappropriate aggressive treatment; nevertheless, precise diagnosis is a challenge due to phenotypic overlap across different histologic subtype. Surgery is the standard of therapeutic approach; literature concerning the benefit of adjuvant treatments is inconclusive and a globally accepted treatment of recurrence does not exist. Targetable mutations in the genes BRAF and FGFR1/2 are recurrently found in these tumors and could take a promising role in future treatment management.

Imaging of extraventricular neurocytoma: a systematic literature review

OBJECTIVE

Extraventricular neurocytoma (EVN) was firstly described in 1997. The current literature regarding imaging of EVN is limited to sporadic case reports and case series. EVN is still poorly considered in the differential diagnosis by neuroradiologists, thus diagnosis remains challenging. In this systematic review, we summarize and discuss computed tomography (CT) and magnetic resonance imaging (MRI) features of EVN cases described in the literature, in order to provide useful informations to neuroradiologists. To the best of our knowledge, this is the most extensive review about imaging of EVN.

MATERIALS AND METHODS

A systematic review of the literature about imaging of EVN cases was done. Only case reports or case series in which imaging (CT and/or MRI) features were deeply described were included in the revision. Eligibility of studies was assessed independently by two authors and any disagreements resolved by discussion.

RESULTS

Our search strategy revealed 224 articles. After implementation of inclusion and exclusion criteria, 35 studies were considered, and a total of 79 cases of EVN were analyzed.

CONCLUSION

EVN has not specific characteristics, with a large and variable imaging spectrum. Usually it appears as a large tumor, with diameters superior to 40 mm, frequently involving the frontal lobe. CT density and MRI signal intensity typically mirror the presence of cystic, solid, or calcified elements; contrast enhancement is visible in 87% of cases. Today, diagnosis of EVN with only imaging techniques is not univocal; neuroradiologists can only suspect this type of lesion, while the definitive diagnosis remains histological.

FGFR- gene family alterations in low-grade neuroepithelial tumors

The discovery of fibroblast growth factor receptor (FGFR) gene family alterations as drivers of primary brain tumors has generated significant excitement, both as potential therapeutic targets as well as defining hallmarks of histologic entities. However, FGFR alterations among neuroepithelial lesions are not restricted to high or low grade, nor to adult vs. pediatric-type tumors. While it may be tempting to consider FGFR-altered tumors as a unified group, this underlying heterogeneity poses diagnostic and interpretive challenges. Therefore, understanding the underlying biology of tumors harboring specific FGFR alterations is critical. In this review, recent evidence for recurrent FGFR alterations in histologically and biologically low-grade neuroepithelial tumors (LGNTs) is examined (namely FGFR1 tyrosine kinase domain duplication in low grade glioma, FGFR1-TACC1 fusions in extraventricular neurocytoma [EVN], and FGFR2-CTNNA3 fusions in polymorphous low-grade neuroepithelial tumor of the young [PLNTY]). Additionally, FGFR alterations with less well-defined prognostic implications are considered (FGFR3-TACC3 fusions, FGFR1 hotspot mutations). Finally, a framework for practical interpretation of FGFR alterations in low grade glial/glioneuronal tumors is proposed.

FGFR- gene family alterations in low-grade neuroepithelial tumors

The discovery of fibroblast growth factor receptor (FGFR) gene family alterations as drivers of primary brain tumors has generated significant excitement, both as potential therapeutic targets as well as defining hallmarks of histologic entities. However, FGFR alterations among neuroepithelial lesions are not restricted to high or low grade, nor to adult vs. pediatric-type tumors. While it may be tempting to consider FGFR-altered tumors as a unified group, this underlying heterogeneity poses diagnostic and interpretive challenges. Therefore, understanding the underlying biology of tumors harboring specific FGFR alterations is critical. In this review, recent evidence for recurrent FGFR alterations in histologically and biologically low-grade neuroepithelial tumors (LGNTs) is examined (namely FGFR1 tyrosine kinase domain duplication in low grade glioma, FGFR1-TACC1 fusions in extraventricular neurocytoma [EVN], and FGFR2-CTNNA3 fusions in polymorphous low-grade neuroepithelial tumor of the young [PLNTY]). Additionally, FGFR alterations with less well-defined prognostic implications are considered (FGFR3-TACC3 fusions, FGFR1 hotspot mutations). Finally, a framework for practical interpretation of FGFR alterations in low grade glial/glioneuronal tumors is proposed.

Extraventricular neurocytoma with ganglioid differentiation of the sellar and parasellar regions in an elderly patient: A case report

Background:

Extraventricular neurocytoma (EVN) is a rare variant of central neurocytoma which arises outside of the ventricular system. Diffuse ganglioid differentiation is a characteristic seen in a subset of these tumors which has an uncertain prognostic significance. Typically, EVN presents in children and young adults. Given the rarity of this tumor, the natural history and response to treatments remain unclear.

Case Description:

We present a case of EVN with diffuse ganglioid differentiation in a 70-year-old male which 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.

Conclusion:

In this report, we review the natural history and clinical course of this patient and summarize the literature regarding this rare pathological entity. Our patient responded well to therapy despite older age, ganglioid differentiation, and higher mitotic index.

Neurocytoma mimicking macroadenoma

Background

Intraventricular and extraventricular central neurocytomas (CN) are equally frequent among 20-40-year-old men and women. However, sellar and suprasellar extraventricular CN are extremely rare, with only 12 reported cases.

Case Description

The authors report the case of 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. Endocrinological evaluation revealed complete loss of pituitary function. The patient was referred to our department and underwent a two-step surgery (using 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 at 3 weeks after admission to our department.

Conclusion

Although extraventricular neurocytomas of the brain are rare, careful preoperative consideration of its anatomy, pathophysiological features, and radiological features can enhance the treatment outcomes.

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.

FGFR1:TACC1 fusion is a frequent event in molecularly defined extraventricular neurocytoma

Extraventricular neurocytoma (EVN) is a rare primary brain tumor occurring in brain parenchyma outside the ventricular system. Histopathological characteristics resemble those of central neurocytoma but exhibit a wider morphologic spectrum. Accurate diagnosis of these histologically heterogeneous tumors is often challenging because of the overlapping morphological features and the lack of defining molecular markers. Here, we explored the molecular landscape of 40 tumors diagnosed histologically as EVN by investigating copy number profiles and DNA methylation array data. DNA methylation profiles were compared with those of relevant differential diagnoses of EVN and with a broader spectrum of diverse brain tumor entities. Based on this, our tumor cohort segregated into different groups. While a large fraction (n = 22) formed a separate epigenetic group clearly distinct from established DNA methylation profiles of other entities, a subset (n = 14) of histologically diagnosed EVN grouped with clusters of other defined entities. Three cases formed a small group close to but separated from the epigenetically distinct EVN cases, and one sample clustered with non-neoplastic brain tissue. Four additional samples originally diagnosed otherwise were found to molecularly resemble EVN. Thus, our results highlight a distinct DNA methylation pattern for the majority of tumors diagnosed as EVN, but also indicate that approximately one third of morphological diagnoses of EVN epigenetically correspond to other brain tumor entities. Copy number analysis and confirmation through RNA sequencing revealed FGFR1-TACC1 fusion as a distinctive, recurrent feature within the EVN methylation group (60%), in addition to a small number of other FGFR rearrangements (13%). In conclusion, our data demonstrate a specific epigenetic signature of EVN suitable for characterization of these tumors as a molecularly distinct entity, and reveal a high frequency of potentially druggable FGFR pathway activation in this tumor group.

Imaging characteristics of cerebral extraventricular neurocytoma with pathological correlation

PURPOSE

Extraventricular neurocytoma (EVN) is an exceedingly rare tumor. In this study, we sought to characterize the imaging and pathological features of this uncommon tumor.

METHODS

Retrospective review of 18 patients (9 male; 9 female) with pathologically confirmed EVN treated at a single center between 2005 and 2017.

RESULTS

All patients had a solitary lesion. Sixteen lesions were found in hemispheres. The greatest tumor diameter ranged from 2.6 to 8 cm. The lesions were generally solid with cystic components; the solid portion appeared isodense or hyperdense on CT, isointense to hypointense on T1WI, and slightly hyperintense on T2WI. Heterogeneous hyperintensity interspersed with isointense or hypointense areas suggestive of hemorrhage, calcification or vascular flow voids were seen on T2WI. Heterogeneous enhancement was noted in 17 lesions; no enhancement was observed in one lesion. Cystic components were observed in 13 lesions; 9 of these showed characteristic perilesional cysts (9/13). Mild to moderate peritumoral edema (15/18), calcification (4/16), intratumoral hemorrhage (11/18) and vascular flow voids (10/16) were observed in some lesions. Pathologically, tumor cells showed round nucleus and fine neuropil matrix. Foci of calcification in the solid portion of the tumor were seen in five cases. Microcystic changes were observed in almost all cases. Some lesions exhibited positive staining for synaptophysin (Syn) (15/16) and neuronal nuclei (NeuN) (7/8). MIB-1 was determined for 10 patients; seven of these had an MIB-1 ≥ 3. These six patients experienced recurrence; four of them relapsed twice.

CONCLUSIONS

EVNs occur as single intracranial solid mass with cystic components (especially peripherally located cysts); solid portion exhibits slight hyperintensity or heterogeneous signal intensity. Mild to moderate peritumoral edema, calcification, intratumoral hemorrhage and vascular flow voids were characteristic features of extraventricular neurocytoma. Positive staining for synaptophysin and neuronal nuclei confirmed the diagnosis. A combination of atypical pathologic features and atypical radiologic features should be considered for prognostic assessment.

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.

Extraventricular Neurocytoma in the Left Frontal Lobe: A Case Report and Literature Review

BACKGROUND

Neurocytoma is a rare brain neoplasm of neuroepithelial origin that occurs predominantly in the ventricular system adjacent to the interventricular foramen and septum pellucidum. However, extraventricular neurocytoma is an extremely rare entity, with poor clinical, radiologic, and histopathological characterization. Here we report a case of an extraventricular parafalcine neurocytoma in the left frontal lobe. We also examine previously reported cases of extraventricular neurocytoma in an attempt to provide an up-to-date summary of the condition.

METHODS

A literature search was performed using PubMed with specific key terms, inclusion criteria, and exclusion criteria. Selected case studies and case series were then compared, and statistical analyses were performed where appropriate. We report a 59-year-old woman presenting with weakness in her right leg and urinary incontinence. Physical examination revealed muscle strength of grade 3/5 in the right lower extremity. Brain magnetic resonance imaging showed a parafalcine mass in the left frontal lobe, with perilesional edema; the cerebral falx and lateral ventricle were shifted due to the compression. Gross total resection was performed.

RESULTS

Histopathological examination revealed a neurocytoma. Immunohistochemical staining showed diffuse positivity for synaptophysin. MIB-1 staining for Ki-67 antibody showed a labeling index of 20%. No adjuvant radiation or chemotherapy was administered. Brain computed tomography performed at a 3-month follow-up showed no signs of recurrence.

CONCLUSION

Extraventricular neurocytoma occurring in the brain parenchyma is a very rare central nervous system tumor. Its clinical and radiologic manifestations are nonspecific. The diagnosis depends on histopathological and immunohistochemical examination. Surgical resection should be the first-choice treatment.

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.

Clinical Features, Treatment, and Long-term Outcomes of Central Neurocytoma: A 20-Year Experience at a Single Center

OBJECTIVE

Central neurocytoma (CN) is a rare central nervous system tumor the optimal management strategy of which remains controversial because of their rarity. Detailed information on CN is necessary to establish optimal management strategies. The purpose of this study was to show the clinical features, treatments, and long-term clinical outcomes of CN.

METHODS

A total of 63 patients with CN were surgically treated between 1995 and 2016 at West China Hospital. All pathologically proven CN cases were identified. Epidemiologic characteristics, clinical features, imaging features, functional outcomes, overall survival, and progression-free survival according to multimodal treatments were reviewed retrospectively.

RESULTS

There were 29 males and 34 females, with a median age of 29 years (range, 15-58 years). Thirty-four patients underwent gross total resection (GTR) and 29 patients underwent subtotal resection (STR). The surgical approaches to CNs in this study included a transcortical approach (39 cases) and an interhemispheric transcallosal approach (24 cases). There were no differences in functional outcomes or initial extent of resection according to the surgical approach used. The extent of resection was GTR in 34 patients (54.0%), and STR in 29 patients (46.0%). At the median follow-up of 74 months (range, 6-205 months), the actuarial 5-year and 10-year overall survival were 93.3% and 85.4%. At the last follow-up, 8 patients had experienced tumor progression. The 5-year and 10-year progression-free rate was 73.4% and 57.5%. The initial extent of resection and multimodal treatment was not related to overall survival; however, the actuarial local control rate differed significantly according to the initial extent of resection and multimodal treatment.

CONCLUSIONS

CN is a rare type of World Health Organization grade II primary brain tumor with a tendency to recur. Complete resection of CNs with maximal safety remains the primary treatment to minimize local progression. Adjuvant radiotherapy should be considered in patients receiving incomplete resection. The long-term clinical outcomes of CN after multimodal treatment seem to be satisfactory.

Clinical, radiological, and histological features and treatment outcomes of supratentorial extraventricular ependymoma: 14 cases from a single center

OBJECTIVE Reports on supratentorial extraventricular ependymoma (STE) are relatively rare. The object of this study was to analyze the clinical, radiological, and histological features and treatment outcomes of 14 patients with STE. METHODS Overall, 227 patients with ependymoma underwent surgical treatment in the authors' department between January 2010 and June 2015; 14 of these patients had STE. Data on clinical presentation, radiological studies, histopathological findings, surgical strategies, and treatment outcomes in these 14 cases were retrospectively analyzed. RESULTS The patients consisted of 6 women and 8 men (sex ratio 0.75). Mean age at diagnosis was 24.5 ± 13.5 years (range 3-48 years). Tumors were predominantly located in the frontal and temporal lobes (5 and 4 cases, respectively). Typical radiological features were mild to moderate heterogeneous tumor enhancements on contrast-enhanced MRI. Other radiological features included well-circumscribed, "popcorn" enhancement and no distinct adjoining brain edema. Gross-total resection was achieved in 12 patients, while subtotal removal was performed in 2. Radiotherapy was administered in 7 patients after surgery. Seven tumors were classified as WHO Grade II and the other 7 were verified as WHO Grade III. The mean follow-up period was 22.6 months (range 8-39 months). There were 3 patients with recurrence, and 2 of these patients died. CONCLUSIONS Supratentorial extraventricular ependymoma has atypical clinical presentations, various radiological features, and heterogeneous histological forms; therefore, definitive diagnosis can be difficult. Anaplastic STE shows malignant biological behavior, a higher recurrence rate, and a relatively poor prognosis. Gross-total resection with or without postoperative radiotherapy is currently the optimal treatment for STE.

Systematic Analysis of Clinical Outcomes Following Stereotactic Radiosurgery for Central Neurocytoma

Central neurocytoma (CN) typically presents as an intraventricular mass causing obstructive hydrocephalus. The first line of treatment is surgical resection with adjuvant conventional radiotherapy. Stereotactic radiosurgery (SRS) was proposed as an alternative therapy for CN because of its lower risk profile. The objective of this systematic analysis is to assess the efficacy of SRS for CN. A systematic analysis for CN treated with SRS was conducted in PubMed. Baseline patient characteristics and outcomes data were extracted. Heterogeneity and publication bias were also assessed. Univariate and multivariate linear regressions were used to test for correlations to the primary outcome: local control (LC). The estimated cumulative rate of LC was 92.2% (95% confidence interval: 86.5-95.7%, p<0.001). Mean follow-up time was 62.4 months (range 3-149 months). Heterogeneity and publication bias were insignificant. The univariate linear regression models for both mean tumor volume and mean dose were significantly correlated with improved LC (p<0.001). Our data suggests that SRS may be an effective and safe therapy for CN. However, the rarity of CN still limits the efficacy of a quantitative analysis. Future multi-institutional, randomized trials of CN patients should be considered to further elucidate this therapy.

Adult Brain Tumors and Pseudotumors: Interesting (Bizarre) Cases

Some brain tumors results are interesting due to their rarity at presentation and overwhelming imaging characteristics, posing a diagnostic challenge in the eyes of any experienced neuroradiologist. This article focuses on the most important features regarding epidemiology, location, clinical presentation, histopathology, and imaging findings of cases considered "bizarre." A review of the most recent literature dealing with these unusual tumors and pseudotumors is presented, highlighting key points related to the diagnosis, treatments, outcomes, and differential diagnosis.

Comprehensive preoperative work-up and surgical treatment of low grade tumor/benign lesion related temporal lobe epilepsy

OBJECTIVE

Generally low-grade tumor/benign lesion related temporal lobe epilepsy (LGT/BL-TLE) is considered easier to treat and has better prognosis when compared to non-lesional TLE. However, multiple disputes exist in surgical management of this epilepsy entity. This study aims to discuss comprehensive preoperative work-up, surgical strategies and outcome of it.

METHODS

A retrospective review of sixty LGT/BL-TLE cases which underwent comprehensive preoperative work-up and then resective surgeries was conducted. Surgical strategies were categorized into limited and expanded resections. Surgical efficacy was evaluated using Engel grading after telephone or clinic follow-up and compared statistically.

RESULTS

Preoperative work-up includes magnetic resonance imaging (MRI), conventional electroencephalography, semiology evaluation, positron emission tomography (PET) and 256-channel dense-array electroencephalography source imaging (256-ch dESI). In aspect of concordance with epileptic lesions demonstrated on MRI, 256-ch dESI was more accurate than PET (72.7% vs. 39.4%) (p<0.05). Limited resections were performed in 28 cases while expanded resections in 32 cases. Altogether the surgical efficacy was: Engel grade I 86.7%, I+II 95.0%. Comparison of surgical outcome showed neither the outcome between limited and expanded resection nor the outcome between mesial and neocortical TLE (mTLE & nTLE) undergoing limited resections was significantly different (p>0.05).

CONCLUSIONS

For LGT/BL-TLE, most surgical strategies can be made preoperatively after comprehensive work-up rather than intraoperatively. Limited and expanded strategies yield similar surgical outcome in either nTLE or mTLE as long as comprehensive work-up supports the strategy and the epileptic lesion is totally removed. 256-ch dESI which can visualize both structural and electrophysiological lesions may be contributable to surgical planning of this entity.

Ventricular Central Neurocytoma: Rate of Shunting and Outcome 2 Years After Total and Subtotal Excision

BACKGROUND

Central neurocytoma is an intraventricular tumor that affects young adults. It has a favorable prognosis after adequate surgical intervention; however, an aggressive course may take place in some cases.

OBJECTIVE

The objective of the study was to evaluate the rate of shunting and the outcome of control measures in patients with central neurocytoma submitted to total and subtotal excision.

METHODS

Twelve patients were included in this study, with a follow-up of 24 months. Data collected included: age, sex, clinical presentation, early morbidity and mortality, radiological findings (tumor location, features, residual, recurrence, and hydrocephalus). All patients underwent surgery for total or subtotal excision through a transcortical approach. External Ventricular Drain (EVD) was inserted then removed or replaced by a shunt. Histopathology and the MIB index were used to confirm diagnosis and guide the follow-up; adjuvant radiotherapy or Gamma Knife radiosurgery were used for residual tumor or recurrence.

RESULTS

The ages of the patients ranged from 14 to 48 years. Two patients died early, after total and subtotal excision, from sepsis and thalamic infarction, respectively. Six patients (60 %) had a total excision; two of them had a high MIB index and showed small recurrence at 12 months and 18 months, respectively, and received Gamma Knife radiosurgery. One of the six patients with total excision needed a shunt, and no shunt was needed in the four otherpatients; a subtotal excision was done for four patients (40 %). An early shunt was inserted for two of these patients, radiosurgery-controlled for one patient, while radiotherapy was used for control in the other three patients; radiotherapy control failed in one patient, who underwent a second surgery at 18 months.

CONCLUSION

Central neurocytoma may have a favorable prognosis, with a lower incidence of shunt insertion throughout its course than that for other intraventricular tumors, if total removal is achieved.

Pediatric Central Neurocytoma

Central neurocytomas are well-differentiated tumors of neuronal origin. These are relatively uncommon in the pediatric population. Anaplastic features reflected by brisk mitotic activity, microvascular proliferation, necrosis, and MIB-1 labeling index >2% or 3% have been proposed to indicate aggressive behavior. Because of its rarity, there is paucity of data regarding the histologic spectrum and outcome of central neurocytomas in children. With this short series, we describe our observations of the clinicopathologic characteristics and outcome of this tumor in children over a 5-year period.

A clinicopathologic study of extraventricular neurocytoma

In 2007, extraventricular neurocytoma was classified as a separate entity among glioneuronal tumors. However, extraventricular neurocytoma is not fully understood and may be misdiagnosed. Here, we describe the clinical and pathological features, prognoses, and treatments of 13 extraventricular neurocytoma cases, and compare their immunophenotypes with those of oligodendroglioma, diffuse astrocytoma, and ependymoma. Six typical and 7 atypical cases comprised the 13 extraventricular neurocytoma cases. Histological features included oligodendroglioma-like perinuclear halo, neuropil-like matrix, ganglion or ganglioid cells, perivascular pseudorosettes, vessel hyalinization, calcifications, and myxoid degeneration. Atypical histological features included increased mitotic figures, focal necrosis, endothelial cell proliferation, and/or a Ki-67 index of >2%. All lesions expressed synaptophysin and microtubule-associated protein-2, which distinguished them from other similar tumors. Two patients with atypical extraventricular neurocytoma had tumor recurrence, one of whom had cerebrospinal fluid dissemination, suggesting that atypical histological features might represent adverse prognostic factors. In conclusion, the present study identified morphological and immunohistochemical features that would aid the differential diagnosis of extraventricular neurocytoma. In addition, radiotherapy with subtotal resection could be considered an effective treatment for extraventricular neurocytoma, but because a pediatric patient died of intracranial hemorrhage during radiotherapy, radiotherapy-related side effects should be considered, especially when treating children. Additional cases with long-term follow-up are needed to develop optimal management protocols for extraventricular neurocytoma.

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.

Progression of atypical extraventricular neurocytoma to anaplastic ganglioglioma

We report a childhood case of thalamic atypical extraventricular neurocytoma that progressed to highly anaplastic ganglioglioma after 8 years of dormancy after subtotal resection and chemotherapy. The neurocytoma displayed immunoreactivity only for synaptophysin, β-catenin, S100, and CD56. The ganglioglioma acquired strong immunoreactivity for chromogranin, glial fibrillary acidic protein, neuron-specific enolase, and p53 and showed a very high proliferation rate approaching 50% in some areas. Tumor transformation was associated with overexpression of components of the sonic hedgehog and Wnt developmental signaling pathways, which are known to regulate tumor-initiating cells in malignant brain neoplasms.

Primary Neurocytoma in the Spinal Cord

Central neurocytoma is defined as an intraventricular benign brain tumor. Extra-ventricular location of central neurocytoma is rare: only nine cases of spinal neurocytoma had been reported in the English literature. We hereby present a case of atypical neurocytoma involving unusual long segments (8-segment) of cervico-thoracic spinal cord in a 29-year-old woman with emphasis on pre- and post-surgical neuroimaging, pathological correlation, and review the pertinent literature.

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.

Extraventricular neurocytoma in the left temporal lobe: A case report and review of the literature

Central neurocytoma (CNC) often develops in the ventricular system adjacent to the interventricular foramen and septum pellucidum. According to the World Health Organization, CNCs are classified as grade II tumors, and in recent years it has been reported that CNCs have occasionally occurred in rare areas of the central nervous system. The current study describes a rare case of CNC located in the left temporal lobe of a 49-year-old man, who had been experiencing headaches for 3 weeks. Computed tomography identified a round, well-demarcated, 3.3-cm tumor in the left temporal lobe. The patient underwent surgery and the tumor was totally resected. Histological analysis demonstrated that the resected tumor tissue contained clusters of small cells with regular nuclear morphology, and round nuclei with fine chromatin. Immunohistochemically, neuronal differentiation markers, including synaptophysin and neuronal nuclear antigen, were expressed in the tumor cells. Histopathological examination of the resected tissue confirmed a diagnosis of extraventricular neurocytoma. Magnetic resonance imaging was performed at 3 months post-surgery and demonstrated no evidence of tumor recurrence.

Clinical manifestations of central neurocytoma

Central neurocytomas (CNs) are rare central nervous system tumors that occur in the lateral ventricles. They are prevalent in young adults and are typically benign with excellent prognosis following surgical resection. Because of the rarity of the disease and its similar features with more common tumors, misdiagnosis becomes an issue. Optimal treatment is achieved only when the correct tumor types are distinguished. Typical clinical manifestations include symptoms of increased intracranial pressure, although no clinical feature is pathognomonic to CN. Radiologic imaging, histology, magnetic resonance spectroscopy, and immunohistochemistry must be used to elucidate tumor characteristics and properly diagnose CN.

Neurocytoma of the spinal cord

This article presents an overview of spinal neurocytomas. A rare manifestation of an uncommon tumor, extraventricular neurocytomas (EVNs) should be included in the differential for spinal intradural and intramedullary tumors. Spinal EVNs are generally benign with an indolent pathologic course but may display a variety of acute or chronic clinical behaviors, depending on their anatomic location. Only a handful of spinal EVNs have been described in the literature, often in the form of individual case reports or small case series. Discussion includes a review of the literature and an overview of the clinical, pathologic, and radiologic features of this rare tumor type, as well as the differential diagnosis, treatment options, and general prognosis.