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Meningiomas are the most common primary intracranial tumors in adults and are increasing in incidence due to the aging population and increased access to neuroimaging. While most exhibit nonmalignant behavior, a subset of meningiomas are biologically aggressive and are associated with treatment resistance, resulting in significant neurologic morbidity and even mortality. In recent years, meaningful advances in our understanding of the biology of these tumors have led to the incorporation of molecular biomarkers into their grading and prognostication. However, unlike other central nervous system (CNS) tumors, a unified molecular taxonomy for meningiomas has not yet been established and remains an overarching goal of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy-Not Official World Health Organization (cIMPACT-NOW) working group. Additionally, clinical equipoise still remains on how specific meningioma cases and patient populations should be optimally managed. To address these existing gaps, members of the International Consortium on Meningiomas including field-leading experts, have prepared this comprehensive consensus narrative review directed toward clinicians, researchers, and patients. Included in this manuscript are detailed overviews of proposed molecular classifications, novel biomarkers, contemporary treatment strategies, trials on systemic therapies, health-related quality-of-life studies, and management strategies for unique meningioma patient populations. In each section, we discuss the current state of knowledge as well as ongoing clinical and research challenges to road map future directions for further investigation.

PURPOSE: NF2-related schwannomatosis (NF2) is characterized by bilateral vestibular schwannomas (VS) often causing hearing and neurologic deficits, with currently no FDA-approved drug treatment. Pre-clinical studies highlighted the potential of mTORC1 inhibition in delaying schwannoma progression. We conducted a prospective open-label, phase II study of everolimus for progressive VS in NF2 patients and investigated imaging as a potential biomarker predicting effects on growth trajectory. METHODS: The trial enrolled 12 NF2 patients with progressive VS. Participants received oral everolimus daily for 52 weeks. Brain imaging was obtained quarterly. As primary endpoint, radiographic response (RR) was defined as ≥ 20% decrease in target VS volume. Secondary endpoints included other tumors RR, hearing outcomes, drug safety and quality of life (QOL). RESULTS: Eight participants completed the trial and four discontinued the drug early due to significant volumetric VS progression. After 52 weeks of treatment, the median annual VS growth rate decreased from 77.2% at baseline to 29.4%. There was no VS RR and 3 of 8 (37.5%) participants had stable disease. Decreased or unchanged VS volume after 3 months of treatment was predictive of stabilization at 12 months. Seven of eight participants had stable hearing during treatment except one with a decline in word recognition score. Ten of twelve participants reported only minimal changes to their QOL scores. CONCLUSIONS: Volumetric imaging at 3 months can serve as an early biomarker to predict long-term sensitivity to everolimus treatment. Everolimus may represent a safe treatment option to decrease the growth of NF2-related VS in patients who have stable hearing and neurological condition. TRN: NCT01345136 (April 29, 2011).

Simple Summary: In this study, we sought to understand the role of NF2 gene mutation in the carcinogenesis of sporadic cancers. NF2 gene mutations are noted in several central nervous system tumors, solid-organ tumors, and skin cancers. We conducted a literature review on eleven different cancers with NF2 gene mutation involvement, summarizing the extent of association and specific biological pathways thought to be affected by NF2 mutations. We synthesized studies across several oncologic fields to consolidate what we know about NF2 gene mutations in cancer development. The Hippo signaling pathway is a biological pathway that is involved in eight of the eleven NF2-mutated cancers studied in this review. Although NF2 mutation has a known interaction with the Hippo signaling pathway, the specific details of this interface remain a topic for further studies. Background/Objectives: With the rise in prevalence of diagnostic genetic techniques like RNA sequencing and whole exome sequencing (WES), as well as biological treatment regiments for cancer therapy, several genes have been implicated in carcinogenesis. This review aims to update our understanding of the Neurofibromatosis 2 (NF2) gene and its role in the pathogenesis of various cancers. Methods: A comprehensive search of five online databases yielded 43 studies that highlighted the effect of sporadic NF2 mutations on several cancers, including sporadic meningioma, ependymoma, schwannoma, mesothelioma, breast cancer, hepatocellular carcinoma, prostate cancer, glioblastoma, thyroid cancer, and melanoma. Of note were key biological pathways implicated in cancer formation resulting from sporadic NF2 mutations. Results: NF2 gene mutations are implicated in over 11 different cancers, including several CNS tumors, soli-organ tumors, and skin cancer. NF2 acts as a driver mutation in some cancers, as a non-driver mutation in some cancers, and has simple associated mutations with other cancers. In terms of biological pathway involvement, 8 of the 11 cancers with NF2 mutations show evidence of Hippo signaling cascade involvement. Conclusions: Several cancers characterized by mutations in the NF2 gene have associations with the Hippo signaling pathway. However, future studies remain to be done to further elucidate the role of the Hippo signaling pathway in the carcinogenesis of human NF2-mutant tumors. The findings of this review provide insights into the role of NF2 mutations in cancers, Hippo signaling in NF2-mutant cancers, and current gaps in our knowledge regarding the two. [ABSTRACT FROM AUTHOR]

Background/Objectives: Vestibular schwannomas (VSs), also called acoustic neuromas, are benign tumors affecting the vestibulocochlear nerve, often leading to hearing loss and balance issues. This condition is particularly challenging in patients with neurofibromatosis type 2 (NF2), where VSs tend to develop bilaterally. Conventional treatments, such as surgery and radiotherapy, although effective, carry risks like hearing loss and nerve damage. Bevacizumab, a VEGF-targeting monoclonal antibody, has emerged as a less invasive treatment option, showing potential for tumor volume reduction and hearing preservation. This systematic review aims to assess the efficacy of bevacizumab in controlling tumor volume, preserving hearing, and identifying associated adverse events. Methods: A comprehensive systematic review was performed using PRISMA guidelines. PubMed and Cochrane Library databases were searched for studies evaluating the effects of bevacizumab on VS, focusing on key outcomes like tumor volume reduction, hearing preservation, and adverse events. Data extraction and quality assessment were independently conducted by two reviewers using the Newcastle-Ottawa Scale. Results: Nine studies involving 176 patients were included. Bevacizumab showed a partial tumor volume reduction (≥20%) in 40% of cases and disease stabilization in 50%, while 10% experienced tumor progression. Hearing outcomes revealed improvement in 36% of patients, stabilization in 46%, and deterioration in 18%. Severe adverse effects, including hypertension and thromboembolic events, occurred in 13% of patients, while 18% reported no side effects. Tumor regrowth was observed in some patients after treatment discontinuation, emphasizing the need for long-term monitoring. Conclusions: Bevacizumab demonstrates effectiveness in managing VS, particularly in NF2 patients, by reducing tumor size and preserving hearing in a substantial proportion of cases. However, the variability in patient response and the risk of adverse events underscore the need for individualized treatment approaches and further research, including randomized controlled trials, to optimize its clinical application. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 2 (NF2), also known as NF2‐related schwannomatosis (SWN), is a rare dominantly inherited genetic disorder mainly characterized by the presence of vestibular schwannomas (VSs) in addition to a range of other tumors that affect both the central and peripheral nervous systems. These tumors include cranial, spinal, peripheral nerve, and intradermal schwannomas, cranial and spinal meningiomas, and intrinsic central nervous system (CNS) tumors, usually spinal ependymomas. Juvenile cataracts are also common in patients with NF2, with most symptoms at presentation being hearing loss and visual disturbances. We present the case of a previously healthy 12‐year‐old girl who presented with postprandial right upper quadrant pain and was found to have a large hydrops of the gallbladder on ultrasound scan of the abdomen. Pathology of the gallbladder post laparoscopic cholecystectomy showed diffuse involvement of the gallbladder by a benign nerve sheath tumor that was suggestive of schwannoma. Further testing confirmed the diagnosis of NF2. This case helps shed light on unusual NF2 symptoms and underscores the importance of recognizing atypical presentations for timely intervention and management. It also adds value to a multidisciplinary approach in diagnosing and managing NF2. [ABSTRACT FROM AUTHOR]

BACKGROUND: Intracochlear schwannomas (ICSs) are a subtype of intralabyrinthine schwannomas, completely located in the cochlear lumen. ICSs are particularly rare in the pediatric population. Putative diagnosis is made on the basis of magnetic resonance findings with signal characteristics that should remain the same at follow-up imaging. METHODS: A retrospective review was performed searching for pediatric patients affected by ICS treated at the Otolaryngology Department, Ospedale Ramazzini, Carpi (Italy), and Otolaryngology and Otoneurosurgery Department, Azienda Ospedaliero-Universitaria di Parma, (Italy). A scoping literature review of the period January 2000 - June 2024 was performed. RESULTS: Two cases of ICS in pediatric patients are described. Neither family history nor genetic signs of neurofibromatosis type II were found. A single report was identified in the literature review. Data analysis resumes the pooled data of the latter case and the authors' patients. The most common symptom at presentation was progressive sensorineural hearing loss (66%). Mean pure tone average at diagnosis was 74.2 dB. Intracochlear location was in the basal turn in 2 cases and in the apical and middle turns in the third patient. All cases initially underwent a "wait and scan" strategy. The mean follow-up time was 23.3 months. CONCLUSION: Management planning of pediatric ICSs should be accurate as surgical removal may require partial or total cochlear demolition, resulting in vestibular dysfunction and precluding future positioning of a cochlear implant. Close clinical and radiological follow-up with serial MRI scans allows to evaluate both symptom progression and rate of growth, in order to provide patients with the best therapeutic option. [ABSTRACT FROM AUTHOR]

Meningioangiomatosis (MAM) remains a poorly understood lesion responsible for epileptic disease. In the past, MAM was primarily described in the context of neurofibromatosis type 2 before being mainly reported sporadically. Moreover, the malformative or tumoral nature is still debated. Because a subset of MAM are associated with meningiomas, some authors argue that MAM corresponds to an infiltration pattern of these tumors. For these reasons, MAM has not been added to the World Health Organization (WHO) Classification of Central Nervous System Tumors as a specific entity. In the present study, we characterized a series of pure MAM (n = 7) and MAM associated with meningiomas (n = 4) using histopathology, immunohistochemistry, genetic (fluorescent in situ and DNA sequencing analyses), and epigenetic (DNA‐methylation profiling) data. We evidenced two distinct morphological patterns: MAM with a fibroblastic‐like pattern having few lesional cells, and MAM with a more cellular pattern. A subset was associated with the genetic alterations previously reported in meningiomas (such as a KMT2C mutation and a hemizygous deletion of chromosome 22q including the NF2 gene). The DNA‐methylation profile, using a t‐distributed stochastic neighbor embedding analysis, evidenced that MAM (pure or associated with meningiomas) clustered in a separate group from pediatric meningiomas. The present results seem to suggest that MAM represents a neoplastic lesion and encourage the further study of similar additional series so that it may be included in a future WHO classification. [ABSTRACT FROM AUTHOR]

Abstract Background NF2-related schwannomatosis (NF2) is associated with various tumors of the central and peripheral nervous system. There is a wide range of disabilities these patients may suffer from and there is no validated clinical classification for disease severity. We propose a clinical classification consisting of three severity grades to assist in patient management. Methods Patient records from 168 patients were screened for most common diagnoses with severe impact on everyday tasks, social interactions and life expectancy. Eight main categories were identified. One point was assigned to each category. Three severity grades were differentiated as follows: grade 1 (mild NF2): 0 points; grade 2 (moderate NF2): < 3 points; grade 3 (severe NF2): ≥ 3 points. This grading system was then evaluated with respect to inter-rater reliability and clinical significance. Results The patients were grouped according to our new clinical grading system into grade 1 in 48% (n = 80), grade 2 in 43% (n = 72), and grade 3 in 10% of patients (n = 16). There was substantial inter-rater reliability between 3 raters with different levels of clinical experience (Fleiss’ kappa = 0.62). The severity grades correlated significantly with hospitalization, number of operations and dependency on implants (such as cochlear implant, auditory brain-stem implants or ventriculoperitoneal shunts). Conclusions Clinical disease severity of NF2 patients is reflected in a simplified and rater-independent score with three grades. The score facilitates communication for medical personnel of varying experience and backgrounds, and adds a clinical tool to decision-making and research.

Schwann cell tumors are the most common cancers of the peripheral nervous system and can arise in patients with neurofibromatosis type-1 (NF-1) or neurofibromatosis type-2 (NF-2). Functional interactions between NF1 and NF2 and broader mechanisms underlying malignant transformation of the Schwann lineage are unclear. Here we integrate bulk and single-cell genomics, biochemistry, and pharmacology across human samples, cell lines, and mouse allografts to identify cellular de-differentiation mechanisms driving malignant transformation and treatment resistance. We find DNA methylation groups of Schwann cell tumors can be distinguished by differentiation programs that correlate with response to the MEK inhibitor selumetinib. Functional genomic screening in NF1-mutant tumor cells reveals NF2 loss and PAK activation underlie selumetinib resistance, and we find that concurrent MEK and PAK inhibition is effective in vivo. These data support a de-differentiation paradigm underlying malignant transformation and treatment resistance of Schwann cell tumors and elucidate a functional link between NF1 and NF2.

Purpose: This retrospective monocentric study aimed to evaluate long-term auditory brainstem implant (ABI) function in patients with neurofibromatosis type 2, and to investigate the prognostic factors for ABI use. Methods: Between 1997 and 2022, 27 patients with at least five years of follow-up underwent implantation with 32 ABIs. At 1- and 5-years post-implantation and at last follow-up, ABIs were classified as used or non-used and the size of the ipsilateral tumor was recorded. For patients who used their ABIs, we assessed speech perception (disyllabic words, MBAA sentences) in quiet conditions with the ABI only, by lip-reading (LR), and with a combination of the two (ABI + LR). Hearing improvement was calculated as Δ ABI = (ABI + LR)–LR scores. Predictive factors for ABI use were analyzed. Results: One year post-implantation, 74% patients were ABI-users and 66% of the ABIs were used. Two of these patients were non-users at five years, and another two at last follow-up (14 ± 5.2 years); 54% of the patients were ABI-users at last follow-up. Δ ABI revealed a hearing improvement of 32–41% (disyllabic words) and 28–37% (MBAA sentences). Among 16 ABIs with at least LR improvement at 1-year post-implantation, 4 decreased their performance, coinciding with a large growing ipsilateral tumor in 3/4 ABIs. We identified no significant prognostic factors for ABI use. Conclusions: ABIs are indicated in case of bilateral deafness with a non-functional cochlear nerve. Half the patients with ABIs used their implants and auditory performance remained stable over time, except in cases of ipsilateral tumor growth. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer deaths worldwide. Significantly activated uridine nucleotide and fatty acid metabolism in HCC cells promote malignant proliferation and immune evasion. Herein, it is demonstrated that the tripartite motif 65 (TRIM65) E3 ubiquitin‐protein ligase, O‐GlcNAcylated via O‐GlcNAcylation transferase, is highly expressed in HCC and facilitated metabolic remodeling to promote the accumulation of products related to uracil metabolism and palmitic acid, driving the progression of HCC. Mechanistically, it is showed that TRIM65 mediates ubiquitylation at the K44 residue of neurofibromatosis type 2 (NF2), the key protein upstream of classical Hippo signaling. Accelerated NF2 degradation inhibits yes‐associated protein 1 phosphorylation, inducing aberrant activation of related metabolic enzyme transcription, and orchestrating metabolic and immune advantages. In conclusion, these results reveal a critical role for the TRIM family molecule TRIM65 in supporting HCC cell survival and highlight the therapeutic potential of targeting its E3 ligase activity to alter the regulation of proteasomal degradation. [ABSTRACT FROM AUTHOR]

A 40-year-old man presented with two asynchronous spinal cord tumors, diagnosed as spinal ependymoma and myxopapillary ependymoma. The tumors were histologically distinct, requiring molecular analysis for accurate diagnosis. Surgical intervention was crucial for treatment, highlighting the importance of molecular diagnostics in guiding therapeutic decisions for rare CNS tumors. The case study underscores the need for continuous evaluation of treatment options for such tumors. [Extracted from the article]

Neurofibromatosis type 2 is a genetic disorder that results in the formation and progressive growth of schwannomas, ependymomas, and/or meningiomas. The NF2 gene encodes the Merlin protein, which links cell cortical elements to the actin cytoskeleton and regulates a number of key enzymes including Group I p21-activated kinases (PAKs), the Hippo-pathway kinase LATS, and mTORC. While PAK1 and PAK2 directly bind Merlin and transmit proliferation and survival signals when Merlin is mutated or absent, inhibition of Group 1 PAKs alone has not proven sufficient to completely stop the growth of NF2-deficient meningiomas or schwannomas in vivo, suggesting the need for a second pathway inhibitor. As the Hippo pathway is also activated in NF2-deficient cells, several inhibitors of the Hippo pathway have recently been developed in the form of YAP-TEAD binding inhibitors. These inhibitors prevent activation of pro-proliferation and anti-apoptotic Hippo pathway effectors. In this study, we show that PAK inhibition slows cell proliferation while TEAD inhibition promotes apoptotic cell death. Finally, we demonstrate the efficacy of PAK and TEAD inhibitor combinations in several NF2-deficient Schwannoma cell lines. [ABSTRACT FROM AUTHOR]

Objectives: The behavior of orbital meningiomas is difficult to predict. The p53 tumor suppressor gene mutation and the neurofibromatosis 2 gene's inactivation in the merlin formation are two of the several mechanisms that contribute to the development of tumors. This considers the comparison of merlin and p53 expression as an inclination to evaluate the orbital meningiomas. Materials and Methods: This investigation is an observational expository considered within the shape of cross-sectional (cross-sectional). The samples/objects of this study were 44 patients with orbital meningioma who had a clinical, radiological, and histopathological diagnosis at the anatomical pathology laboratory at Cicendo Eye Hospital and Hasan Sadikin Bandung in 2017-2020, then an immunohistochemical examination of merlin and p53 expression was performed. Results: The study indicated that there was no relationship between p53 expression and orbital meningioma grading, also there is no relationship between merlin expression and orbital meningioma grading. However, based on the analysis test results, grade 3 orbital meningiomas tended to have a positive p53 expression rather than a negative expression and tend to have a negative merlin expression instead of a positive. Conclusion: Meningiomas with negative merlin expression have a tendency to express positive p53. Likewise, the higher grade (grade 3) tends to express positive p53 and negative merlin, which may play a key role in tumorigenesis of orbital meningioma, hence, an added value for clinical information and behavioral descriptions of orbital meningioma itself. [ABSTRACT FROM AUTHOR]

Introduction CyberKnife (CK) radiosurgery is a treatment strategy for vestibular schwannoma (VS). Objectives To evaluate hearing preservation (HP) after CK for VS. Data Synthesis The study was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, and it was registered at the International Prospective Register of Systematic Reviews (PROSPERO, under number CRD42021250300). The inclusion criteria were based on the population, intervention, comparison, outcome, timing and study design (PICOTS) strategy: population – patients with VS; intervention – CK; Comparison – none; Outcome – serviceable HP defined by Gardner and Robertson as grades I or II, or by the American Academy of Otolaryngology and Head and Neck Surgery as classes A or B; timing – mean follow-up longer than 1 year; and study design – retrospective or prospective studies. The exclusion criteria were: studies not published in English; studies published before January 2000 and after October 2021; and studies only including patients with neurofibromatosis type 2 or submitted to a previous treatment. The PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, LILACS, and IBECS databases were used and last searched on October 27th, 2021. Statistical heterogeneity was assessed using I2 statistics. The appraisal checklist was used to assess the risk of bias in the included studies. A total of 222 studies were analyzed, and 13 were included in the synthesis, which represents 493 participants with serviceable hearing before intervention. The mean HP rate after CK using a random effects model was of 68% (95% confidence interval [95%CI]: 59–76%) at a mean follow-up of 42.96 months. Conclusion The longer follow-up period was associated with a lower HP rate after CK radiosurgery for VS in the qualitative synthesis. [ABSTRACT FROM AUTHOR]

Neurofibromatosis is one of the most common genetic diseases. It is inherited in an autosomal dominant manner. It is divided into two genetically distinct subtypes, characterized by multiple skin lesions and tumors of the peripheral and central nervous system. Neurofibromatosis type 1, or Recklinghausen's disease, is the most common phakomatosis. The disease is genetically determined by a mutation of the neurofibromin-1 gene on chromosome 17. Neurofibromatosis type 2 accounts for 3% of all cases. The disease is genetically determined - caused by a mutation of the neurofibromin-2 gene on chromosome 22. The diagnostic and therapeutic process of neurofibromatosis is a major challenge for clinicians. Given the complexity of the problem, we have reviewed the literature on the diagnostic and therapeutic possibilities of the disease. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 2 (NF2) is a tumor suppressor gene implicated in various tumors, including mesothelioma, schwannomas, and meningioma. As a member of the ezrin, radixin, and moesin (ERM) family of proteins, merlin, which is encoded by NF2, regulates diverse cellular events and signalling pathways, such as the Hippo, mTOR, RAS, and cGAS-STING pathways. However, the biological role of NF2 in tumorigenesis has not been fully elucidated. Furthermore, cross-cancer mutations may exert distinct biological effects on tumorigenesis and treatment response. In addition to the functional inactivation of NF2, the codeficiency of other genes, such as cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B), BRCA1-associated protein-1 (BAP1), and large tumor suppressor 2 (LATS2), results in unique tumor characteristics that should be considered in clinical treatment decisions. Notably, several recent studies have explored the metabolic and immunological features associated with NF2, offering potential insights into tumor biology and the development of innovative therapeutic strategies. In this review, we consolidate the current knowledge on NF2 and examine the potential connection between cancer metabolism and tumor immunity in merlin-deficient malignancies. This review may provide a deeper understanding of the biological roles of NF2 and guide possible therapeutic avenues. [ABSTRACT FROM AUTHOR]

Neurofibromatosis Type II (NFII) is a genetic condition caused by loss of the NF2 gene, resulting in activation of the YAP/TAZ pathway and recurrent Schwann cell tumors, as well as meningiomas and ependymomas. Unfortunately, few pharmacological options are available for NFII. Here, we undertake a genome-wide CRISPR/Cas9 screen to search for synthetic-lethal genes that, when inhibited, cause death of NF2 mutant Schwann cells but not NF2 wildtype cells. We identify ACSL3 and G6PD as two synthetic-lethal partners for NF2, both involved in lipid biogenesis and cellular redox. We find that NF2 mutant Schwann cells are more oxidized than control cells, in part due to reduced expression of genes involved in NADPH generation such as ME1. Since G6PD and ME1 redundantly generate cytosolic NADPH, lack of either one is compatible with cell viability, but not down-regulation of both. Since genetic deficiency for G6PD is tolerated in the human population, G6PD could be a good pharmacological target for NFII. Few therapeutic options are available for patients with Neurofibromatosis Type II. Here, the authors identify G6PD as a potential pharmacological target and show that NF2 mutant Schwann cells are in an oxidized state and die when G6PD is inhibited. [ABSTRACT FROM AUTHOR]

Background: In most cases, intralabyrinthine schwannoma (ILS) occurs in patients with unilateral hearing deterioration or neurofibromatosis type II (NF II). The pattern of localization of these tumors varies but mostly affects the cochlea. Extirpation of the cochlear schwannoma, if hidden by the cochlea modiolus, is difficult under the aspect of complete removal. Therefore, a tissue removal device (TRD) was designed and tested in temporal bones. The principle of handling the new device is a pushing and pipe cleaner handling inside the cochlea. This present study aimed to describe the first in vivo experience with the newly developed TRD for removing cochlear intralabyrinthine schwannomas. Methods: In three patients, the TRD was used for the tumor removal of cochlear schwannomas. In two patients with a cochlear schwannoma in combination with a cochlea implantation and one patient suffering from NF II, a cochlear schwannoma was removed with the TRD. The access was performed with a posterior tympanotomy, an enlarged round window approach and an additional second turn access. The device was inserted and extracted gradually from the second turn access until the rings were visible in the second turn access. By pushing and pipe cleaner handling, the tumors were removed. An MRI control was performed on the day postoperatively with a T1 GAD sequence. Results: Tumor removal with the TRD was performed in a 15-min procedure without any complications. An MRI control confirmed complete removal on the postoperative day in all cases. Conclusions: In vivo handling of the device confirmed straightforward handling for the tumor removal. MRI scanning showed complete removal of the tumor by the TRD. [ABSTRACT FROM AUTHOR]

Objectives: Simultaneous removal and cochlear implantation (CI) have been reported in intralabyrinthine and intracochlear schwannoma. A wide range of postoperative hearing outcomes have been reported after CI in these cases. This study evaluated the outcomes of performing a simultaneous resection of Schwannoma in cochlea and cochlear implantation (CI), aiming to assess the effectiveness of this combined surgical approach for hearing rehabilitation with CI. Methods: This retrospective case series was conducted at a tertiary care center. The study included four consecutive patients with profound sensorineural hearing loss due to a mass inside the cochlea. These patients underwent simultaneous single-sided CI and tumor resection performed by the same surgeon. Preoperative and postoperative audiological assessments were conducted to evaluate the patients' hearing outcomes before and after the surgical intervention. Results: Simultaneous CI with tumor resection was successful in all cases. Two of the four patients had a unilateral tumor, while the other two had a bilateral tumor with the involvement of the internal auditory canal and cerebellopontine angle (neurofibromatosis type 2 (NF2)). In two cases of unilateral tumor, aided free-field pure tone average (PTA) was 26 dB, and 46 dB hearing level (HL), and word recognition score (WRS) at 65 dB was 40% and 68%, respectively, 3 months after surgery. In two cases of tumor with NF2, aided free-field PTA was 36 dB and 60 dB HL, and both cases showed 0% WRS at 65 dB 3 months after surgery. Conclusions: Simultaneous schwannoma excision and CI in patients with Schwannoma inside cochlea are surgically practical and safe. Postoperatively, there was a notable improvement in hearing in cases of sporadic schwannoma, regardless of the type of CI used. However, there was 0% WRS in the two NF2 patients with a mass in the internal auditory canal. [ABSTRACT FROM AUTHOR]

Simple Summary: The hallmark of NF2 is bilateral vestibular schwannomas, which progressively enlarge, leading to sensorineural hearing loss, tinnitus, facial weakness, and pain that translates to social impairment and clinical depression. To better understand disease progression and characterize treatment response, we developed a panel of five tests suitable for the mouse vestibular schwannoma model and investigated how tumor growth and treatment affect gait, coordination, and motor function. These methods, paired with hearing tests, enable a comprehensive evaluation of tumor-induced neurological deficits and facilitate the assessment of the effectiveness of novel therapeutics to improve NF2 treatments. NF2-related Schwannomatosis (NF2-SWN) is a disease that needs new solutions. The hallmark of NF2-SWN, a dominantly inherited neoplasia syndrome, is bilateral vestibular schwannomas (VSs), which progressively enlarge, leading to sensorineural hearing loss, tinnitus, facial weakness, and pain that translates to social impairment and clinical depression. Standard treatments for growing VSs include surgery and radiation therapy (RT); however, both carry the risk of further nerve damage that can result in deafness and facial palsy. The resultant suffering and debility, in combination with the paucity of therapeutic options, make the effective treatment of NF2-SWN a major unmet medical need. A better understanding of these mechanisms is essential to developing novel therapeutic targets to control tumor growth and improve patients' quality of life. Previously, we developed the first orthotopic cerebellopontine angle mouse model of VSs, which faithfully mimics tumor-induced hearing loss. In this model, we observed that mice exhibit symptoms of ataxia and vestibular dysfunction. Therefore, we further developed a panel of five tests suitable for the mouse VS model and investigated how tumor growth and treatment affect gait, coordination, and motor function. Using this panel of ataxia tests, we demonstrated that both ataxia and motor function deteriorated concomitantly with tumor progression. We further demonstrated that (i) treatment with anti-VEGF resulted in tumor size reduction, mitigated ataxia, and improved rotarod performance; (ii) treatment with crizotinib stabilized tumor growth and led to improvements in both ataxia and rotarod performance; and (iii) treatment with losartan did not impact tumor growth nor ameliorate ataxia or motor function. Our studies demonstrated that these methods, paired with hearing tests, enable a comprehensive evaluation of tumor-induced neurological deficits and facilitate the assessment of the effectiveness of novel therapeutics to improve NF2 treatments. [ABSTRACT FROM AUTHOR]

Schwannomas are common benign tumours arising from the myelin sheath of peripheral nerves. These tumours are usually located in the intradural and extramedullary regions. The common sites are cervical (58%) and thoracic region (32%), followed by the lumbar region (10%). Intramedullary location is rare and if present, is usually associated with neurofibromatosis 1 and 2 (NF-1 and 2). Intramedullary brainstem schwannomas without NF are uncommon, and to the best of the authors' knowledge, only 19 cases have been reported to date. It was first described by James Watson Kernohan, an Irish-American pathologist, in 1931. The rarity of these tumours in this location is due to the absence of Schwann cells in this area. There are several hypotheses postulating the presence of these tumours in this location. The exact cause is not yet known. The authors here present a case of intramedullary brainstem ancient schwannoma with an unusual clinicoradiological presentation, which raised suspicion of Glioma with the possibility of Astrocytoma. The patient presented with right-sided neck stiffness and shoulder pain for a period of four months. Total excision of the tumour was performed, and the postoperative period was uneventful with clinical improvement in the patient. Histomorphology raised the suspicion of a tumour of glial origin with the possibility of Astrocytoma; Immunohistochemistry (IHC) helped in reaching the definitive diagnosis of Ancient Schwannoma. Thus, a combined approach of clinicoradiological, as well as histomorphology and IHC, is essential for a definitive diagnosis of these tumours. Future multicentric studies are required to elucidate the pathogenesis of the location of these tumours. [ABSTRACT FROM AUTHOR]

Introduction: Programmed death‐ligand 1 (PD‐L1) expression is an immune evasion mechanism that has been demonstrated in many tumors and is commonly associated with a poor prognosis. Over the years, anti‐PD‐L1 agents have gained attention as novel anticancer therapeutics that induce durable tumor regression in numerous malignancies. They may be a new treatment choice for neurofibromatosis type 2 (NF2) patients. Aims: The aims of this study were to detect the expression of PD‐L1 in NF2‐associated meningiomas, explore the effect of PD‐L1 downregulation on tumor cell characteristics and T‐cell functions, and investigate the possible pathways that regulate PD‐L1 expression to further dissect the possible mechanism of immune suppression in NF2 tumors and to provide new treatment options for NF2 patients. Results: PD‐L1 is heterogeneously expressed in NF2‐associated meningiomas. After PD‐L1 knockdown in NF2‐associated meningioma cells, tumor cell proliferation was significantly inhibited, and the apoptosis rate was elevated. When T cells were cocultured with siPD‐L1‐transfected NF2‐associated meningioma cells, the expression of CD69 on both CD4+ and CD8+ T cells was partly reversed, and the capacity of CD8+ T cells to kill siPD‐L1‐transfected tumor cells was partly restored. Results also showed that the PI3K–AKT–mTOR pathway regulates PD‐L1 expression, and the mTOR inhibitor rapamycin rapidly and persistently suppresses PD‐L1 expression. In vivo experimental results suggested that anti‐PD‐L1 antibody may have a synergetic effect with the mTOR inhibitor in reducing tumor cell proliferation and that reduced PD‐L1 expression could contribute to antitumor efficacy. Conclusions: Targeting PD‐L1 could be helpful for restoring the function of tumor‐infiltrating lymphocytes and inducing apoptosis to inhibit tumor proliferation in NF2‐associated meningiomas. Dissecting the mechanisms of the PD‐L1‐driven tumorigenesis of NF2‐associated meningioma will help to improve our understanding of the mechanisms underlying tumor progression and could facilitate further refinement of current therapies to improve the treatment of NF2 patients. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 2 (NF2)-related schwannomatosis is a rare autosomal dominant monogenic disorder caused by mutations in the NF2 gene. The hallmarks of NF2-related schwannomatosis are bilateral vestibular schwannomas (VS). The current treatment options for NF2-related schwannomatosis, such as observation with serial imaging, surgery, radiotherapy, and pharmacotherapies, have shown limited effectiveness and serious complications. Therefore, there is a critical demand for novel effective treatments. Gene therapy, which has made significant advancements in treating genetic diseases, holds promise for the treatment of this disease. This review covers the genetic pathogenesis of NF2-related schwannomatosis, the latest progress in gene therapy strategies, current challenges, and future directions of gene therapy for NF2-related schwannomatosis. [ABSTRACT FROM AUTHOR]

Objective: Vestibular schwannomas (VS), benign tumors stemming from the eighth cranial nerve's Schwann cells, are associated with Merlin gene mutations, inflammation, and the tumor microenvironment (TME), influencing tumor initiation, maintenance, and potential neural dysfunction. Understanding TME composition holds promise for systemic therapeutic interventions, particularly for NF2-related schwannomatosis. Methodology: A retrospective analysis of paraffin-embedded tissue from 40 patients (2013-2020), evenly divided by neurofibromatosis type 2 status, with further stratification based on magnetic resonance imaging (MRI) progression and hearing function. Immunohistochemistry assessed TME components, including T-cell markers (CD4, CD8, CD25), NK cells (CD7), and macrophages (CD14, CD68, CD163, CCR2). Fiji software facilitated image analysis. Results: T-cell markers (CD4, CD8, CD7) exhibited low expression in VS, with no significant NF2-associated vs. sporadic distinctions. Macrophage-related markers (CD14, CD68, CD163, CCR2) showed significantly higher expression (CD14: p = 0.0187, CD68: p < 0.0001, CD163: p = 0.0006, CCR2: p < 0.0001). CCR2 and CD163 significantly differed between NF2-associated and sporadic VS. iNOS, an M1-macrophage marker, was downregulated. CD25, a regulatory T-cell marker, correlated significantly with tumor growth dynamics (p = 0.016). Discussion: Immune cells, notably monocytes and macrophages, crucially contribute to VS pathogenesis in both NF2-associated and sporadic cases. Significant differences in CCR2 and CD163 expression suggest distinct immune responses. Regulatory T-cells may serve as growth dynamic markers. These findings highlight immune cells as potential biomarkers and therapeutic targets for managing VS. [ABSTRACT FROM AUTHOR]

BACKGROUND: Meningiomas occur in 80% of persons with neurofibromatosis 2 (NF2) and cause significant mortality and morbidity, yet there are no effective medical treatments. NF2-deficient tumors have constitutive activation of mammalian/mechanistic target of rapamycin (mTOR), and treatment with mTORC1 inhibitors results in growth arrest in a minority of tumors, with paradoxical activation of the mTORC2/AKT pathway. We studied the effect of vistusertib, a dual mTORC1/mTORC2 inhibitor, in NF2 patients with progressive or symptomatic meningiomas. METHODS: Vistusertib was administered orally at 125 mg twice daily for 2 consecutive days each week. The primary endpoint was the imaging response in the target meningioma, defined as a volume decrease of 20% compared with the baseline. Secondary endpoints included toxicity, imaging response of nontarget tumors, quality of life, and genetic biomarkers. RESULTS: Eighteen participants (13 female), median age of 41 (range, 18-61) years, were enrolled. In target meningiomas, the best response was partial response (PR) in 1/18 tumors (6%) and stable disease (SD) in 17/18 tumors (94%). For all measured intracranial meningiomas and vestibular schwannomas, the best imaging response was PR in 6/59 tumors (10%) and SD in 53 (90%). Treatment-related grade 3/4 adverse events occurred in 14 (78%) participants, and 9 participants discontinued treatment due to side effects. CONCLUSIONS: Although the study did not meet the primary endpoint, vistusertib treatment was associated with high rates of SD in progressive NF2-related tumors. However, this dosing regimen for vistusertib was poorly tolerated. Future studies of dual mTORC inhibitors for NF2 should focus on optimizing tolerability and evaluating the relevance of tumor stability in participants.

Schwannomas are common sporadic tumors and hallmarks of familial neurofibromatosis type 2 (NF2) that develop predominantly on cranial and spinal nerves. Virtually all schwannomas result from inactivation of the NF2 tumor suppressor gene with few, if any, cooperating mutations. Despite their genetic uniformity schwannomas exhibit remarkable clinical and therapeutic heterogeneity, which has impeded successful treatment. How heterogeneity develops in NF2-mutant schwannomas is unknown. We have found that loss of the membrane:cytoskeleton-associated NF2 tumor suppressor, merlin, yields unstable intrinsic polarity and enables Nf2-/- Schwann cells to adopt distinct programs of ErbB ligand production and polarized signaling, suggesting a self-generated model of schwannoma heterogeneity. We validated the heterogeneous distribution of biomarkers of these programs in human schwannoma and exploited the synchronous development of lesions in a mouse model to establish a quantitative pipeline for studying how schwannoma heterogeneity evolves. Our studies highlight the importance of intrinsic mechanisms of heterogeneity across human cancers.

Schwannomatosis is characterized by a predisposition to develop multiple schwannomas and rarely meningiomas. People with schwannomatosis are most commonly present between the second and fourth decades of life. The most common feature is localized or diffuse pain or an asymptomatic mass. Schwannomas most commonly involve peripheral and spinal nerves. We report the case of a woman who was initially referred to our department because of suspected neurofibromatosis type 2. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, we explored the use of bevacizumab as a treatment for NF2-related schwannomatosis, a condition characterized by the development of schwannomas on both vestibulocochlear nerves. This study revealed that the majority of patients experienced either improved or preserved hearing and effective control of the targeted vestibular schwannoma with bevacizumab. However, common adverse events included hypertension and fatigue, and severe adverse events led to treatment discontinuation in a quarter of the patients. Thus, while bevacizumab demonstrates positive effects on hearing, tumor control, and symptomatology in NF2-related schwannomatosis, careful consideration of potential side effects is crucial. (1) Background: NF2-related schwannomatosis, characterized by the development of bilateral vestibular schwannomas, often necessitates varied treatment approaches. Bevacizumab, though widely utilized, demonstrates variable effectiveness on hearing and tumor growth. At the same time, (serious) adverse events have been frequently reported. (2) Methods: A single center retrospective study was conducted, on NF2-related schwannomatosis patients treated with bevacizumab from 2013 to 2023, with the aim to assess treatment-related and clinical outcomes. Outcomes of interest comprised hearing, radiologic response, symptoms, and adverse events. (3) Results: Seventeen patients received 7.5 mg/kg bevacizumab for 7.1 months. Following treatment, 40% of the patients experienced hearing improvement, 53%, stable hearing, and 7%, hearing loss. Vestibular schwannoma regression occurred in 31%, and 69% remained stable. Further symptomatic improvement was reported by 41%, stable symptoms by 47%, and worsened symptoms by 12%. Treatment discontinuation due to adverse events was observed in 29% of cases. Hypertension (82%) and fatigue (29%) were most frequently reported, with no occurrences of grade 4/5 toxicities. (4) Conclusion: Supporting previous studies, bevacizumab demonstrated positive effects on hearing, tumor control, and symptoms in NF2-related schwannomatosis, albeit with common adverse events. Therefore, careful consideration of an appropriate management strategy is warranted. [ABSTRACT FROM AUTHOR]

S100 protein expression levels and neurofibromatosis type 2 (NF-2) mutations result in different disease courses in meningiomas. This study aimed to investigate non-invasive biomarkers of NF-2 copy number loss and S100 protein expression in meningiomas using morphological, radiomics, and deep learning-based features of susceptibility-weighted MRI (SWI). This retrospective study included 99 patients with S100 protein expression data and 92 patients with NF-2 copy number loss information. Preoperative cranial MRI was conducted using a 3T clinical MR scanner. Tumor volumes were segmented on fluid-attenuated inversion recovery (FLAIR) and subsequent registration of FLAIR to high-resolution SWI was performed. First-order textural features of SWI were extracted and assessed using Pyradiomics. Morphological features, including the tumor growth pattern, peritumoral edema, sinus invasion, hyperostosis, bone destruction, and intratumoral calcification, were semi-quantitatively assessed. Mann–Whitney U tests were utilized to assess the differences in the SWI features of meningiomas with and without S100 protein expression or NF-2 copy number loss. A logistic regression analysis was used to examine the relationship between these features and the respective subgroups. Additionally, a convolutional neural network (CNN) was used to extract hierarchical features of SWI, which were subsequently employed in a light gradient boosting machine classifier to predict the NF-2 copy number loss and S100 protein expression. NF-2 copy number loss was associated with a higher risk of developing high-grade tumors. Additionally, elevated signal intensity and a decrease in entropy within the tumoral region on SWI were observed in meningiomas with S100 protein expression. On the other hand, NF-2 copy number loss was associated with lower SWI signal intensity, a growth pattern described as "en plaque", and the presence of calcification within the tumor. The logistic regression model achieved an accuracy of 0.59 for predicting NF-2 copy number loss and an accuracy of 0.70 for identifying S100 protein expression. Deep learning features demonstrated a strong predictive capability for S100 protein expression (AUC = 0.85 ± 0.06) and had reasonable success in identifying NF-2 copy number loss (AUC = 0.74 ± 0.05). In conclusion, SWI showed promise in identifying NF-2 copy number loss and S100 protein expression by revealing neovascularization and microcalcification characteristics in meningiomas. [ABSTRACT FROM AUTHOR]

Neurofibromatosis 2 (NF2) is characterised by numerous tumours in the central and peripheral nervous systems due to NF2 gene abnormalities that cause the tumour suppressor protein, Merlin, to disappear. Often referred to as Multiple Inherited Schwannomas, Meningiomas, and Ependymomas (MISME), a distinctive characteristic of NF2 is bilateral vestibular schwannomas manifesting in late adolescence with symptoms such as sensorineural hearing loss, tinnitus, and balance issues. Two distinct phenotypes, Wishart and Feiling-Gardner, characterise NF2. This case report discusses the case of a paediatric patient who presented with bilateral hearing loss, giddiness, and blurring of vision and sought a Magnetic Resonance Imaging (MRI) examination which revealed bilateral vestibular schwannomas, non vestibular schwannomas, left sphenoid wing meningiomas, multidirectional spinal schwannomas, spinal nerve sheath tumours, and lesions in the retroperitoneal region. Despite an absent family history, significant involvement of cranial nerves strongly indicates classical NF2. Management focuses on preserving function, and surgery is contemplated for symptomatic lesions and tumours causing cord compression. Gamma Knife radiosurgery and targeted therapies have been investigated. [ABSTRACT FROM AUTHOR]

Meningiomas are the most common primary brain tumours. The incidence of meningiomas increases progressively with age and might be related to general diseases, e.g. neurofibromatosis type 2 and exposure to radiation. Ocular symptoms are mainly reported in sphenoorbital meningiomas with proptosis, decreased visual acuity and visual field scotomas being the most common. Despite the fact that benign and slow-growing tumours with orbital extension predominate among meningiomas, early diagnosis increases the probability of safe neurosurgical removal and full visual recovery. Thus, healthcare professionals need to be aware of the symptoms of meningiomas for the proper differential diagnosis of potentially life- and sight-threatening diseases. We present a case report of a patient complaining of a black spot moving in front of her eye for 3 months, which was misdiagnosed as a floater. We aim to emphasize the proper history taking and ancillary testing scheme when the initial diagnosis is uncertain. Additionally, sphenoorbital meningiomas’ ocular symptoms, post-surgery follow-up regimen and risk factors for regrowth are reviewed. [ABSTRACT FROM AUTHOR]

Abstract Objective To obtain updated estimates of the incidence and prevalence of neurofibromatosis type 1 (NF1) and type 2 (NF2). Study design We conducted a systematic search of NF1 and NF2 incidence or prevalence studies, in OVID Medline, OVID Embase, Web of Science, and Cinahl. Studies were appraised with the Joanna Briggs Institute Prevalence Critical Appraisal tool. Pooled incidence and prevalence rates were estimated through random-effects meta-analysis. Results From 1,939 abstracts, 20 studies were fully appraised and 12 were included in the final review. Pooled NF1 prevalence was 1 in 3,164 (95%CI: 1 in 2,132-1 in 4,712). This was higher in studies that screened for NF1, compared to identification of NF1 through medical records (1 in 2,020 and 1 in 4,329, respectively). NF1 pooled birth incidence was 1 in 2,662 (95%CI: 1 in 1,968-1 in 3,601). There were only 2 studies on NF2 prevalence, so data were not pooled. Pooled NF2 birth incidence was 1.08 per 50,000 births (95%CI: 1 in 32,829-1 in 65,019). Conclusion We present updated estimates of the incidence and prevalence of NF1 and NF2, to help plan for healthcare access and allocation. The prevalence of NF1 from screening studies is higher than from medical record studies, suggesting that the disease may be under recognized. More studies are needed regarding the prevalence of NF2.

Purpose. Specific retinal abnormalities of neurofibromatosis type 2 (NF2) commonly include retinal astrocytoma and combined hamartoma of the retina and retinal pigment epithelium. Vasculopathy is an uncommon manifestation of NF2. We reported an NF2 patient presenting with retinal ischemia. Observations. An 18-year-old healthy Chinese female with acute decreased vision. The fundus examination and optical coherence tomography revealed optic disc hamartoma in the right eye and paracentral acute middle maculopathy (PAMM) and cotton wool spot indicating retinal ischemia in the left eye. Brain MRI showed bilateral acoustic neuroma, parasellar meningioma, and cervical extramedullary tumor. The genetic test confirmed the diagnosis of NF2. Conclusions and Importance. Our case suggests that retinal ischemia could be the presenting sign of NF2. NF2 could be associated with retinal vasculopathy in addition to retina tumors. [ABSTRACT FROM AUTHOR]

Background: Schwannomas are benign nerve sheath tumors that can either be sporadic or part of neurofibromatosis type 2 (NF2). Tumors of the brachial plexus (BP) with both supra- and infraclavicular components are uncommon and represent a challenge to complete surgical resection. There are few reports on single clavicular osteotomies for BP exposure; however, there are currently no reports of utilization of a clavicular window for a large schwannoma resection. Case Description: We report a case of a patient with a schwannoma spanning the BP roots to the cords, with the majority involving the retro clavicular inferior trunk in the setting of NF2. The patient underwent previous subtotal resection and had postoperative enlargement of the residual mass. A gross total resection was made possible by the creation of a clavicular window to expose the BP. A 2 cm segment piece of the mid-clavicle was removed, allowing for roughly 6 cm of mediolateral exposure through clavicular distraction. This clavicular window facilitated complete exposure of the BP schwannoma underneath the clavicle as well as unobstructed exposure of supraclavicular and infraclavicular tumor. The segment was then refixed with a plate after resection of the tumor. Conclusion: The use of a clavicular window allowed for extensive exposure of the trunks and divisions of the BP to achieve a gross total resection in this case. The clavicular window approach may provide a benefit for optimizing exposure in the setting of lesions involving the trunks and divisions that the clavicle would traditionally obstruct. [ABSTRACT FROM AUTHOR]

Background Although rare in small vestibular schwannomas, preoperative facial nerve paresis is often present in giant schwannomas. Preserving facial nerve function in these cases remains a herculean task. This study evaluates the facial functions after complete tumor removal and whether preoperative facial nerve involvement affects postoperative functional status. Methods This retrospective study from January 2014 to August 2021 excluded nongiant tumors (< 4 cm), neurofibromatosis type 2 cases, incomplete removals, redo surgeries, deaths, and cases done without nerve monitoring. These were grouped into preoperative facial palsy present (PFP) and no preoperative facial palsy (NFP). Facial nerve functions were assessed on first postoperative day, at the time of discharge, and at last follow-up and dichotomized into two groups: nondisfiguring (House–Brackmann [HB] grades I–III) and disfiguring (HB grades IV–VI). The cohort outcomes of patients with nondisfiguring PFP (HB grades I–III) were also analyzed. Results There were 88 cases (PFP, n = 57; NFP, n = 31). Facial nerve was preserved anatomically in 62 (70.45%) patients (PFP, n = 38; NFP, n = 24) without any statistical difference (p = 0.29). Statistically significant disfiguring facial outcomes (HB IV, V, VI) were seen in patients with preoperative facial palsy (p = 0.01); however, a comparison of facial functions in patients with only nondisfiguring PFP with those in NFP group did not show the statistical difference (p = 0.12). Conclusion Facial nerve palsy present before surgery does not seem to be a deterrent to intraoperative preservation of facial nerve during complete removal of giant vestibular schwannomas. Patients with nondisfiguring facial palsies have postoperative facial functions comparable to those without facial palsy. [ABSTRACT FROM AUTHOR]