Histology and molecular aspects of central neurocytoma

Long-term outcomes of central neurocytoma - an institutional experience

INTRODUCTION

Central Neurocytoma (CN) is a rare, WHO grade 2 brain tumor that predominantly affects young adults. Gross total resection (GTR) is often curative for CNs, but the optimal treatment paradigm including incorporation of RT, following subtotal resection (STR) and for scarcer pediatric cases has yet to be established.

METHODS

Patients between 2001 and 2021 with a pathologic diagnosis of CN were reviewed. Demographic, treatment, and tumor characteristics were recorded. Recurrence free survival (RFS) and overall survival (OS) were calculated according to the Kaplan Meier-method. Post-RT tumor volumetric regression analysis was performed.

RESULTS

Seventeen adults (≥ 18 years old) and 5 children (< 18 years old) met the criteria for data analysis (n = 22). With a median follow-up of 6.9 years, there was no tumor-related mortality. Patients who received STR and/or had atypical tumors (using a cut-off of Ki-67 > 4%) experienced decreased RFS compared to those who received GTR and/or were without atypical tumors. RFS at 5 years for typical CNs was 67% compared to 22% for atypical CNs. Every pediatric tumor was atypical and 3/5 recurred within 5 years. Salvage RT following tumor recurrence led to no further recurrences within the timeframe of continued follow-up; volumetric analysis for 3 recurrent tumors revealed an approximately 80% reduction in tumor size.

CONCLUSION

We provide encouraging evidence that CNs treated with GTR or with RT after tumor recurrence demonstrate good long-term tumor control.

Intraventricular central neurocytoma molecularly defined as extraventricular neurocytoma: a case representing the discrepancy between clinicopathological and molecular classifications

Central neurocytoma (CN) is classically defined by its intraventricular location, neuronal/neurocytic differentiation, and histological resemblance to oligodendroglioma. Extraventricular neurocytoma (EVN) shares similar histological features with CN, while it distributes any site without contact with the ventricular system. CN and EVN have distinct methylation landscapes, and EVN has a signature fusion gene, FGFR1-TACC1. These characteristics distinguish between CN and EVN. A 30-year-old female underwent craniotomy and resection of a left intraventricular tumor at our institution. The histopathology demonstrated the classical findings of CN. Adjuvant irradiation with 60 Gy followed. No recurrence has been recorded for 25 years postoperatively. RNA sequencing revealed FGFR1-TACC1 fusion and methylation profile was discrepant with CN but compatible with EVN. We experienced a case of anatomically and histologically proven CN in the lateral ventricle. However, the FGFR1-TACC1 fusion gene and methylation profiling suggested the molecular diagnosis of EVN. The representative case was an "intraventricular" neurocytoma displaying molecular features of an "extraventricular" neurocytoma. Clinicopathological and molecular definitions have collided in our case and raised questions about the current definition of CN and EVN.

Radiotherapy Protocol of Central Neurocytoma for Resource-limited Settings in the Absence of Official Guidelines: A Case Report and Review of the Literature

BACKGROUND: Central neurocytoma (CN) is one of the rarest brain tumors which can cause considerable threats to the patient. Studies and trials regarding its treatment are scarce, and no official guidelines are dedicated to this disease. The main principle of treatment generally consists of surgery and radiotherapy. The choice of radiotherapy is divided into conventional fractionated radiotherapy and stereotactic radiosurgery (SRS). However, access to SRS in developing countries such as Indonesia is still limited. AIM: We report a case delineating the timeline and process of treatment in CN with a review of the literature. METHODS: We report the case of a 29-year-old woman with a solid inhomogeneous mass (AP 5.63 × CC 5.36 × LL 5.16 cm) in the right ventricle, attached to the septum pellucidum, as displayed on the magnetic resonance imaging (MRI). The patient had been vomiting for the past three weeks and presented with bidirectional horizontal nystagmus. RESULTS: Cognitive evaluation with Montreal Cognitive Assessment (MoCA-Ina) demonstrated a mild cognitive impairment. Biopsy was performed, and pathology analysis revealed some cells with fibrillary background and some with a honeycomb-like appearance. The immunohistochemistry staining showed positive results with synaptophysin and neuronal nuclear protein. According to the WHO classification of the central nervous system tumors, the profile favored CN Grade II. Subtotal resection (STR) was performed to reduce the tumor mass, which was measured with MRI 2-month post-surgery (AP 4.09 × CC 3.01 × LL 4.13 cm) and then followed by an external radiation program. Using intensity modulated radiation therapy (IMRT), a total dose of 54 Gy was given in 27 fractions, with the average planning target volume of 54.3 Gy. There was a minuscule reduction in tumor mass as seen in post-radiotherapy MRI (AP 4.00 × CC 3.86 × LL 3.63 cm). After the last session and at the 18-month follow-up, the patient did not have any complaints or abnormalities during clinical assessment. Reevaluation using MoCA-Ina showed an improved cognitive function. CONCLUSIONS: In line with recent evidence, we demonstrated that STR followed by IMRT with the dosage of 54 Gy in 27 fractions was a feasible treatment strategy for CN that resulted in cognitive improvement, with no side effects.

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.

The importance of staged surgery for giant atypical central neurocytoma

The aim of this article is to discuss the importance of staged surgeries when approaching atypical central neurocytoma in children. Also, we show the preoperative embolization of the lesion as a maneuver to reduce the intraoperative bleeding. Central neurocytomas represent less than 0.5% of all intracranial tumors, and atypical central neurocytomas usually have unfavorable outcome, with high recurrence rate. The intraventricular location is frequent, with a predilection for the lateral ventricles. When completely resected, these lesions have a good prognosis. We report a case of a 12-year old male patient that presented with a history of headache for about 6 months, which worsened for 1 week prior to admission. Magnetic resonance imaging (MRI) brain showed a massive lesion occupying both lateral ventricles. He underwent a microsurgical treatment of a highly vascularized lesion, but the perioperative bleeding required interruption of the surgery. Thus, a preoperative embolization was able to occlude most arterial feeders and allowed subtotal resection in a second surgery. The patient had complete neurological recovery despite immediate post-operative deficits, and the histopathology was suggestive of atypical neurocytoma. Two-stage surgery with preoperative adjuvant embolization is a feasible strategy for treatment of large central neurocytomas in children.

A Mechanism Leading to Changes in Copy Number Variations Affected by Transcriptional Level Might Be Involved in Evolution, Embryonic Development, Senescence, and Oncogenesis Mediated by Retrotransposons

In recent years, more and more evidence has emerged showing that changes in copy number variations (CNVs) correlated with the transcriptional level can be found during evolution, embryonic development, and oncogenesis. However, the underlying mechanisms remain largely unknown. The success of the induced pluripotent stem cell suggests that genome changes could bring about transformations in protein expression and cell status; conversely, genome alterations generated during embryonic development and senescence might also be the result of genome changes. With rapid developments in science and technology, evidence of changes in the genome affected by transcriptional level has gradually been revealed, and a rational and concrete explanation is needed. Given the preference of the HIV-1 genome to insert into transposons of genes with high transcriptional levels, we propose a mechanism based on retrotransposons facilitated by specific pre-mRNA splicing style and homologous recombination (HR) to explain changes in CNVs in the genome. This mechanism is similar to that of the group II intron that originated much earlier. Under this proposed mechanism, CNVs on genome are dynamically and spontaneously extended in a manner that is positively correlated with transcriptional level or contract as the cell divides during evolution, embryonic development, senescence, and oncogenesis, propelling alterations in them. Besides, this mechanism explains several critical puzzles in these processes. From evidence collected to date, it can be deduced that the message contained in genome is not just three-dimensional but will become four-dimensional, carrying more genetic information.

Atypical central neurocytoma with leptomeningeal dissemination: a case report

BACKGROUND

Central neurocytomas represent 0.25-0.5% of all intracranial tumors in adults. Leptomeningeal spread is uncommon, and the exact incidence of meningeal spread is unknown due to sparse literature. We present the clinical course and management outcome of a case of atypical central neurocytoma with leptomeningeal spread.

CASE PRESENTATION

A young gentleman, who initially presented with memory loss, was found to have a right intra-axial periventricular mass on imaging. He underwent subtotal resection, and operative histopathology suggested a periventricular atypical neurocytoma. In view of subtotal resection, adjuvant focal radiation therapy was recommended, but he developed headache and blurring of vision 10 days postoperatively. Contrast enhanced craniospinal magnetic resonance imaging (MRI) showed residual primary tumor as well as diffuse leptomeningeal spread. Cerebrospinal fluid cytology also showed malignant cells. After tumor board discussion, craniospinal axis irradiation was advised and delivered. He remained disease-free for 10 months after radiation therapy, but then developed local and spinal recurrence, and offered salvage chemotherapy. His general condition deteriorated following chemotherapy with disease progression, and he was subsequently advised best supportive care.

CONCLUSION

Leptomeningeal dissemination in atypical neurocytomas portends an aggressive course and adverse prognosis; management decisions may need tailoring as per individual presentation.

Atypical central neurocytoma with novel EWSR1-ATF1 fusion and MUTYH mutation detected by next-generation sequencing

We present the case of a 13-year-old boy with a very unusual periventricular atypical central neurocytoma with unique molecular features treated with subtotal surgical resection and photon intensity-modulated radiotherapy. Histological features were most consistent with atypical central neurocytoma. However, next-generation sequencing analysis revealed a novel EWSR1-ATF1 gene fusion (EWSR1-ATF1) as well as a MUTYH mutation. The EWSR1-ATF1 raised the possibility of Ewing sarcoma or angiomatoid fibrous histiocytoma, however, FLI-1 immunohistochemistry was negative. MUTYH mutations have been reported in diffuse midline paediatric glioma. The role of EWSR1-ATF1 and MUTYH mutations in central nervous system tumours is not well established. We present the first case of EWSR1-ATF1 and MUTYH mutation in a rare paediatric atypical central neurocytoma. Further studies are indicated to elucidate the consequences of these gene alterations in the context of paediatric central nervous system tumours as well as to investigate the potential role for targeted therapies.

Central Neurocytoma: Rare Presentation in Fourth Ventricle and Review of Literature

Central neurocytomas are rare tumors, typically found in the third ventricle. We present the unusual case of a fourth ventricular central neurocytoma in a 70-year-old female presenting with imbalance and headaches, with an enhancing fourth ventricular mass on imaging. We examine the details of her clinical presentation, imaging characteristics, histopathologic analysis, and postoperative course. We performed a critical literature review of fourth ventricular central neurocytoma, identifying 6 previously reported cases. In contrast to our patient, the majority of these cases were in young males. The 2 females with fourth ventricular neurocytoma developed it at a much later age (mean 63.5 years) than their male counterparts (mean 22.8 years; P = 0.005). Despite being a rare cause for a fourth ventricular lesion, given the appropriate clinical context and radiographic findings, this should remain part of the differential diagnosis.

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.

Central, Extraventricular and Atypical Neurocytomas: a Clinicopathologic Study of 35 Cases from Pakistan Plus a Detailed Review of the Published Literature

BACKGROUND

Central neurocytomas are rare neuronal neoplasms with a favorable prognosis. They are typically located in the lateral ventricles of the brain and mostly histologically correspond to WHO grade II with a Mib 1 labelling index of <2%. Similar tumors located in the cerebral hemispheres and spinal cord, for example, are called "extraventricular neurocytomas". A few tumors histologically show atypia, mitoses, vascular proliferation and/or necrosis and a Mib 1 index >2 % and are designated as "atypical neurocytomas.

AIM

The aim of our study was to describe the common as well as unusual morphologic features and the role of various immunohistochemical stains in the diagnosis of these rare tumors.

MATERIALS AND METHODS

We retrieved and reviewed 35 cases diagnosed between 2001 and 2015.

RESULTS

Sixty percent of patients were males, and the mean age was 26 years. 31 cases (88.6%) were intraventricular and 4(11.4%) were extraventricular. Histologically, 6 cases (17.1%) were compatible with "atypical neurocytomas". All cases showed the classic morphology comprising nests and sheets of uniform, round cells with uniform round to oval nuclei with finely speckled chromatin and perinuclear cytoplasmic clearing (halos). All cases also showed delicate, fibrillary, neuropil-like matrices. Other common histologic features included capillary-sized blood vessels in a branching pattern in 57.1%, foci of calcification in 34.3% and perivascular pseudorosettes in 20%. Rare findings included Homer- Wright or true rosettes in 8.6% and ganglioid cells in 2.9%. Synaptophysin was the most consistent and valuable marker, being positive in almost all cases. GFAP positivity in tumor cells was seen in 25.7% of cases. Follow up was available in 13 patients. Of these 9 had histologically typical and 4 had atypical tumors. Only 1 (with an atypical neurocytoma) died, probably due to complications of surgery within one month, while 12 (including 3 with atypical neurocytomas) remained alive. Recurrence developed in 1 of these 12 patients (histologically consistent with typical morphology) almost 9 years after surgery. Only 4 patients, including 2 with atypical tumors, received postoperative radiotherapy, all with surgery in 2010 or later. Overall, prognosis was excellent with prolonged, recurrence free survival and most patients, even without receiving radiation therapy, were alive and well for many years, even a decade or more after surgery, without developing any recurrence, indicating the benign nature of these neoplasms.