Schwannoma Research Articles

Intratumoral injection of schwannoma with attenuated Salmonella typhimurium induces antitumor immunity and controls tumor growth

Schwannomas are slow-growing benign neoplasms that develop throughout the body causing pain, sensory/motor dysfunction, and death. Because bacterial immunotherapy has been used in the treatment of some malignant neoplasms, we evaluated attenuated Salmonella typhimurium strains as immunotherapies for benign murine schwannomas. Several bacterial strains were tested, including VNP20009, a highly attenuated strain that was previously shown to be safe in human subjects with advanced malignant neoplasms, and a VNP20009 mutant that was altered in motility and other properties that included adherence and invasion of cultured mammalian cells. VNP20009 controlled tumor growth in two murine schwannoma models and induced changes in cytokine and immune effector cell profiles that were consistent with induction of enhanced innate and adaptive host immune responses compared with controls. Intratumoral (i.t.) injection of S. typhimurium led to tumor cell apoptosis, decreased tumor angiogenesis, and lower growth of the injected schwannoma tumors. Invasive VNP20009 was significantly more efficacious than was a noninvasive derivative in controlling the growth of injected tumors. Bacterial treatment apparently induced systemic antitumor immunity in that the growth of rechallenge schwannomas implanted following primary bacterial treatment was also reduced. Checkpoint programmed death-1 (PD-1) blockade induced by systemic administration of anti-PD-1 antibodies controlled tumor growth to the same degree as i.t. injection of S. typhimurium, and together, these two therapies had an additive effect on suppressing schwannoma growth. These experiments represent validation of a bacterial therapy for a benign neoplasm and support development of S. typhimurium VNP20009, potentially in combination with PD-1 inhibition, as a schwannoma immunotherapy.

Evaluation of spinal tumors and its comparison with histopathological findings

Objective: The objective of the study is usefulness of diagnostic MRI in evaluation of spinal tumors. Methodology: This cross-sectional study was carried out in Radiology Department, Dhiraj Hospital, SBKS medical college, Pipariya, Vadodara. The data was collected from July 2021 to March 2022 and total 60 patients were included in the study. Data was collected from MRI diagnosed spinal tumors who attended at Radiology and Imaging department from OPD and indoor patients. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MRI for evaluation of spinal tumors were detected. Results: Out of 60 patients 31 (51.6%) was intradural extramedullary, 15 (25.0%) was extradural and 13 (21.6%) was intramedullary. Distribution of patients according to MR diagnosis, among the 60 patients 49 were diagnosed spinal tumor and 11 were not spinal tumor by MRI. Among the 49 spinal tumor diagnosed 13 (26.5%) were schwannoma, 02(4.0%) were neuro fibroma, 12(24.4%) were meningioma, 08(16.3%) were ependymoma, 06(12.2%) were astrocytoma, 03(6.1%) were metastasis and 2 (4.0%) was osteoblastoma. Out of all cases 49 were diagnosed as spinal tumour by MRI and among them 48 were confirmed by histopathological evaluation. They were true positive.

Schwann Cells in Peripheral Cancers: Bystanders or Promoters?

The tumor microenvironment is subject to intense investigation in terms of its influence on tumorigenesis. Despite the fact that Schwann cells are cancer cells' early interaction partners, investigations on tumor progression and the molecular drivers of carcinogenesis do not place enough emphasis on them. Recent studies have shown that malignant cells and nerves interact on several levels during early carcinogenesis. For instance, the emergence of nerves in cancer, known as cancer neo-neurogenesis, is one important mechanism that contributes to cancer progression. Recent studies on Schwann cells brought the investigation of tumor-nerve interactions to a whole new level. Schwann cells make up the majority of glial cells in the peripheral nervous system, are outstandingly plastic cells, and serve a variety of roles in most organs. All these properties make Schwann cells excellent potential targets for tumor cells to exploit and turn them into promoters of carcinogenesis. In the present review, the distinctive features of Schwann cell-tumor cell interactions and the implications of this interaction on the tumor microenvironment are outlined. Further, this study points out the neglected aspects of Schwann cells in the tumor microenvironment and provides a potential new avenue for future research.

Coronavirus Transmission during Mastoidectomy after Craniotomy to Remove Schwannoma Tumor: Danger to Surgical Team Members

NOT APPLICABLE

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part II: Trigeminal and facial nerve schwannomas (CN V, VII).

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations. A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the second of a three-part series describing non-vestibular schwannomas (V, VII). A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies, and follow-up management. This article represents the consensually derived opinion of the task force with respect to the treatment of trigeminal and facial schwannoma. The aim of treatment is maximal safe resection with preservation of function. Careful thought is required to select the appropriate surgical approach. Most middle fossa trigeminal schwannoma tumours can be safely accessed by a subtemporal extradural middle fossa approach. The treatment of facial nerve schwannoma remains controversial.

A Rare Case Report on Non-Functioning Benign Spindle Cell Neoplasm-Adrenal Schwannoma

Schwannoma or benign tumor of the myelin sheath which are rare and can be functioning or non-functioning that are difficult to diagnose preoperatively. Visceral schwannoma in the adrenal region is extremelyrare, accounting for only 0.7% of the adrenal tumors. Here we report such a rare case of Adrenal schwanomma in 40 years old female patient with hypothyroidism.

The Lipid Asset Is Unbalanced in Peripheral Nerve Sheath Tumors.

Peripheral nerve sheath tumors (PNSTs) include schwannomas, neurofibromas (NFs), and plexiform neurofibromas (PNFs), among others. While they are benign tumors, according to their biological behavior, some have the potential for malignant degeneration, mainly PNFs. The specific factors contributing to the more aggressive behavior of some PNSTs compared to others are not precisely known. Considering that lipid homeostasis plays a crucial role in fibrotic/inflammatory processes and in several cancers, we hypothesized that the lipid asset was also unbalanced in this group of nerve tumors. Through untargeted lipidomics, NFs presented a significant increase in ceramide, phosphatidylcholine, and Vitamin A ester. PNFs displayed a marked decrease in 34 out of 50 lipid class analyzed. An increased level of ether- and oxidized-triacylglycerols was observed; phosphatidylcholines were reduced. After sphingolipidomic analysis, we observed six sphingolipid classes. Ceramide and dihydroceramides were statistically increased in NFs. All the glycosylated species appeared reduced in NFs, but increased in PNFs. Our findings suggested that different subtypes of PNSTs presented a specific modulation in the lipidic profile. The untargeted and targeted lipidomic approaches, which were not applied until now, contribute to better clarifying bioactive lipid roles in PNS natural history to highlight disease molecular features and pathogenesis.

Correlation of vestibular schwannoma tumor with facial nerve weakness, hypoesthesia of face, and disequilibrium

Introduction: Vestibular schwannoma is the most common lesion in the cerebellopontine angle. Some of the most common symptoms arise as the tumor grows bigger such as disequilibrium, hypoesthesia of the face, and facial nerve paresis. Based on the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) and the Consensus Meeting on Systems for Reporting Results in Acoustic Neuroma, there is still no clarity of a single method used to measure the tumor itself.Methods: This was a retrospective study to analyze the correlation between the size (anteroposterior and mediolateral) of the vestibular schwannoma with disequilibrium, hypoesthesia of the face, and facial nerve paresis among the patients in the Neurosurgery Department of Hasan Sadikin Hospital Bandung from January 2014 to December 2019. The data was analyzed using Spearman and Binary Logistic Regression.Results: A total of 58 patients were included in this study with median age was 43 years, ranging from 21 – 72 years. The most common symptoms were disequilibrium (48.27%), followed by facial nerve paresis (39.65%) and hypoesthesia of face (20.68%). The mean anteroposterior size was 3.8 ± 1.17 cm and the mean mediolateral size was 3.0 ± 1.01 cm. There were significant correlation between disequilibrium with anteroposterior size (r = 0.385; p = 0.003) and mediolateral size (r = 0.409; p = 0.001). There were also significant correlation between facial nerve paresis with anteroposterior size (r = 0.458; p = 0.000) and mediolateral size (r = 0.321, p = 0.014).Conclusion: There were significant correlations between the anteroposterior and mediolateral size of the tumor with the occurrence of disequilibrium and facial nerve paresis in patients with vestibular schwannoma.Keywords: diameter, disequilibrium, facial nerve paresis, hypoesthesia of the face, vestibular schwannoma

Scoring system for intraoperative diagnosis of intracranial schwannoma by squash cytology.

To assess the utility of a newly developed squash cytology (SC)-based scoring system for accurate intraoperative diagnosis of schwannoma. We first compared SC-based and frozen section (FS) diagnoses with final pathological diagnoses of schwannoma (16 cases), meningioma (39 cases) and low-grade astrocytoma (16 cases). Then, by logistic regression modeling, we identified features of SC preparations that were independently predictive of schwannoma. To develop a diagnostic scoring system, we assigned one point to each feature, and performed receiver operating characteristic analysis to determine the score cut-off value that was most discriminatory for differentiating schwannoma from the other tumour types. We then compared accuracy, sensitivity, and specificity of diagnosis before and after the application of the scoring system. Overall diagnostic concordance rates for SC and FS were almost the same, at 73.2% (52/71) and 77.5% (55/71 cases), respectively. Of the 16 SC features entered into the analysis, the following nine were found to independently predict schwannoma, and were thus incorporated into the scoring system: smooth cluster margins, few or no isolated tumour cells, fibrillary stroma, spindle-shaped nuclei, parallel arrangement of stroma, parallel arrangement of nuclei, presence of anisonucleosis, absence of nucleoli, and hemosiderin deposition. A cut-off score of four items yielded the best sensitivity, specificity and predictive values for prediction of schwannoma. Use of the scoring system improved accuracy of intraoperative diagnosis from 80.3% to 94.4%, sensitivity from 56.2% to 93.8%, and specificity from 87.3% to 94.5%. Our proposed SC-based scoring system will increase accuracy of intraoperative diagnosis of schwannoma vs non-schwannoma tumours.

CSIG-01. EPIGENETIC REPROGRAMMING DRIVES MALIGNANT PERIPHERAL NERVE SHEATH TUMOR (MPNST) DE-DIFFERENTIATION AND TREATMENT RESISTANCE

Abstract Schwann cell derived tumors comprising schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors are the most common malignancies of the peripheral nervous system. While schwannomas and neurofibromas are benign, MPNSTs are malignant, metastasize, and respond poorly to treatment. Neurofibromas and MPNSTs are associated with loss of NF1, a tumor suppressor that inhibits Ras/MEK signaling, and MPNSTs alone are distinguished by loss of the Polycomb Repressive Complex 2 (PRC2), an epigenetic regulator of methylation. To understand the genomic mechanisms of Schwann cell tumorigenesis and treatment resistance, we performed DNA methylation profiling, RNA-sequencing, and whole exome sequencing of primary Schwann cell tumor resection specimens (n=119 total: n=66 schwannoma, n=13 neurofibroma, n=40 MPNSTs). Hierarchical clustering identified three epigenetic Schwann cell tumor groups with transcriptional differences in PRC2 target genes associated with Schwann cell differentiation. Integrating biochemical and genomic approaches in primary human tumor cell lines from NF1 intact peripheral nerve, NF1 mutant neurofibromas, and MPNSTs, we found MPNST and neurofibroma cell lines with CRISPR knockout SUZ12 or EZH1/2 neurofibroma cell lines demonstrated repression of Schwann cell differentiation genes and induction of Ras signaling target genes. Further, MPNST cells deficient in PRC2 and NF1 exhibited increased basal active Ras-GTP levels, and therapeutically, PRC2 deficient MPNST cell lines were more resistant to the MEK inhibitor selumetinib and radiotherapy when compared to NF1-deficient neurofibroma cells. Single cell RNA sequencing analysis suggested distinct mechanisms of selumetinib resistance in PRC2 intact neurofibroma cells compared to PRC2-deficient MPNST cells. Taken together, our data demonstrate the importance of epigenetic dysregulation in malignant Schwann cell transformation and suggest differentiation status underlies a novel mechanism of MEK inhibitor resistance.

Solitary congenital neurofibroma with overlying melanocytic hyperplasia.

The common embryonic origin of neuroid and melanocytic cells justifies the simultaneous presence of the two cell types in the same neoformation (3). Neurofibroma (NF) can be solitary, diffuse when it has a large extension, and plexiform when it appears as a collection of multiple nodules and cordoniform structures. 10% of diffuse NFs and almost all plexiform NFs are associated with neurofibromatosis (1, 2). Then there is the so-called pigmented or melanotic NF, in which a part of the cells making up the neoplasm is loaded with melanin; this finding is present exclusively in syndromic NF, ie associated with neurofibromatosis. Thus, screening for neurofibromatosis is warranted in the case of plexiform, diffuse, multi-element and melanotic NF (4). In 28% of syndromic NFs and in 4.6% of sporadic NFs there is also a proliferation of epidermal melanocytes, most often in the form of lentiginous melanocytic hyperplasia, but exceptionally in the form of junctional nevus (4). Before assuming that melanocytic hyperplasia is related to NF, it must be considered that melanocytic hyperplasia is also found in cafe au lait spots and therefore we could face a cafe au lait spot superimposed on the NF; this hypothesis should be discarded since lentiginous hyperplasia is also found in sporadic NF and because in any case the histological finding does not always correspond to a clinically evident hyperpigmentation. A casual collision between two different pathologies could also be hypothesized, but this hypothesis is discarded because the limits of melanocytic hyperplasia coincide perfectly with those of the underlying NF (4).

Genomic Analysis and Biochemical Investigation Reveal Mechanisms of Schwann Cell Transformation and Treatment Resistance in Malignant Peripheral Nerve Sheath Tumors (MPNSTs)

<h3>Purpose/Objective(s)</h3> In contrast to benign Schwann cell derived tumors such as neurofibromas and schwannomas, malignant peripheral nerve sheath tumors (MPNSTs) metastasize, and have poor outcomes. MPNSTs are associated with loss of <b>NF1</b>, a tumor suppressor that inhibits Ras signaling, and loss of Polycomb Repressive Complex 2 (PRC2) which resulting in epigenetic dysregulation. Translationally, MPNSTs are resistant to Ras/MEK inhibition with selumetinib and radiation therapy yet the mechanisms underlying how PRC2 loss cooperates with Ras misactivation to drive transformation and treatment resistance remains unclear. Here, we performed DNA methylation profiling and RNA-sequencing of Schwann cell tumors and cell lines as well as investigated <b>in vitro</b> responses to radiotherapy and selumetinib. <h3>Materials/Methods</h3> We identified 119 Schwann cell tumor resection specimens with sufficient tissue for DNA methylation profiling (66 schwannoma, 13 neurofibroma, 40 MPNSTs) and RNA-sequencing (23 schwannoma, 9 neurofibroma, 9 MPNSTs). To study cell signaling and treatment responses, we utilized primary human cell lines generated from <b>NF1</b> intact peripheral nerve, <b>NF1</b> mutant neurofibromas, and MPNSTs (n = 6). We assessed Ras signal transduction by immunoblot/immunoprecipitation for downstream effectors and performed cell viability assays following selumetinib or radiotherapy. <h3>Results</h3> Principal component analysis (PCA) of DNA methylation and RNA-sequencing data demonstrated a gradient of epigenetic signatures across Schwann cell tumors, with schwannomas comprising a distinct cluster from neurofibromas and MPNST. Moreover, differential DNA methylation and RNA-sequencing analyses both revealed enrichment for PRC2 target genes and repression of Schwann cell differentiation genes in MPNSTs. RNA-sequencing of MPNST versus neurofibroma cell lines demonstrated a PRC2 mediated signature enriched for cell differentiation genes and negative feedback regulators of Ras signaling, suggesting PRC2 dysregulation mediates de-differentiation and increased Ras pathway output in MPNSTs. In contrast to neurofibroma cells, MPNST cells were deficient in PRC2 and <b>NF1</b> while exhibiting increased basal active Ras-GTP levels insensitive to serum starvation. PRC2 deficient MPNST cell lines were more resistant to selumetinib and radiation therapy when compared to <b>NF1</b> deficient neurofibroma cells. <h3>Conclusion</h3> PRC2 loss causes epigenetic dysregulation that may mediate Schwann cell de-differentiation programs and altered Ras signaling in MPNSTs compared to neurofibromas. Translationally, these epigenetic changes may contribute to increased resistance to targeted therapy and radiation. The mechanisms underlying transformation and treatment resistance upon PRC2 loss are under further investigation.

The clinico-pathologic profile of primary and recurrent orbital/periorbital plexiform neurofibromas (OPPN).

To evaluate and compare the clinical and histopathological profile of primary and recurrent orbital-periorbital plexiform neurofibromas (OPPN) in patients with neurofibromatosis type 1. We retrospectively evaluated 43 primary or recurrent neurofibroma (NF) specimens from 26 patients (2002 to 2018) at the King Khaled Eye Specialist Hospital, Saudi Arabia. Demographics, clinical presentation, and surgical intervention data were collected. Histopathological specimens were studied with hematoxylin-eosin, Alcian blue, and immunohistochemical markers; S-100, CD44, CD117, smooth muscle actin (SMA), neurofilament, and Ki-67. Of the 43 NFs specimens, 20 were primary and 23 recurrent tumors. For primary NF, the ratio of plexiform to the diffuse type was 13:7, however in recurrent tumors was 3:8 after the first recurrence, and 1:5 after multiple recurrences. Of the 17 patients with primary tumors that had paired recurrent tumors, 12/17 (70.6%) primary NFs were plexiform and 5/17 (29.4%) were diffuse. However, when tumors recurred, 13/17 tumors (76.5%) were diffuse and only 4/17 tumors (23.5%) had a plexiform pattern. The odds of a tumor having a diffuse pattern in recurrent NF was significantly higher than the plexiform pattern [OR = 7.8 (95% confidence interval 1.69:36.1) P = 0.008]. Primary plexiform NFs underwent an excision at a significantly younger age than the diffuse type. Recurrent NFs had significantly higher CD44, CD117, and neurofilament labeling (P = 0.02, P = 0.01 and P<0.001 respectively) but had significantly decreased Alcian blue, and S-100 labeling (P = 0.03, and P = 0.02 respectively) compared to primary tumors. SMA and Ki-67 proliferation index were not different between primary and recurrent NFs (P = 0.86, and P = 0.3 respectively). There appears to be a high risk for primary plexiform NFs to develop a diffuse histologic pattern when they recur. Immunohistochemical staining suggests a role of mast cells (CD117) and expression of infiltration makers (CD44) in the transformation of plexiform tumors to the diffuse phenotype.

Use of a new mouse schwannoma tumour model to monitor changes in peripheral nerve morphology in Merlin null Schwann cells

Abstract Aims Our lab is interested in signals that trigger schwannoma tumour formation and we have previously shown that peripheral nerve injury triggers tumour formation in nerves with Schwann cell-specific loss of the Merlin (NF2) tumour suppressor. The Ras/Raf/MAPK/ERK pathway activity in myelinating Schwann cells is involved in nerve regeneration, causing demyelination and recruitment of inflammatory cells in areas of nerve damage, as well as dedifferentiation of myelinating Schwann cells into a repair-competent state. We have used a mouse model expressing a tamoxifen-inducible Raf-Kinase estrogen receptor fusion protein (Raf-TR) in myelinating Schwann cells of the PNS in either a control wild-type Merlin or Merlin-null background. This allows us to determine the effects of an injury-like signal in Schwann cells and its role in generating schwannoma tumour development. We present here a detailed analysis of the proliferation of Schwann cells within the nerve and morphological changes in PNS structure following Raf-TR activation. Method The P0-promotor driving the Raf-TR transgene is active in myelinating Schwann cells but inactive in the non-myelinating population, allowing specific targeting of the myelinating Schwann cell population. In addition to the Raf-TR gene, the mice exhibit a separate P0-promotor controlled Cre floxed NF2 gene which undergoes Cre-mediated recombinase at embryonic day 13.5 causing NF2 knockout in all developing Schwann cells. Mice aged between 4-6 weeks received intraperitoneal injections of either 2mg Tamoxifen or oil vehicle for 5 consecutive days and were then studied at either 10 or 21 days post-first injection. The peripheral nervous system of the mice was studied with fluorescent immuno-histochemistry staining, semithin sections and transmission electron microscopy (TEM) on sciatic nerves and dorsal root ganglia (DRG). Results Activation of the Ras/Raf/MAPK/ERK pathway in NF2 null Schwann cells led to higher rates of proliferation within sciatic nerves at 10d post-tamoxifen injections. At both 10d and 21d Raf-TR+ NF2-null mice sciatic nerve fascicles were visibly larger with significantly more cell bodies present than controls, however at 21d the rate of proliferation had reduced. In the DRG, proliferation was higher in Raf-TR+ NF2-null mice compared to controls, with proliferation remaining high at 21 days. Quantitative imaging of peripheral nerve semi-thins analysed to date showed no significant difference in the number of myelin rings present in the fascicles between different genotypes. Additionally, dual immuno-histochemistry staining with Myelin Basic Protein and EdU, markers for myelin and proliferation respectively, appeared to show proliferation in the non-myelinating Schwann cell population. Results from staining with other cell markers will also be presented, as well as a detailed analysis of nerve structure using TEM. Conclusion While developmental myelination of Merlin-null Schwann cells appears largely normal, the reaction of Merlin-null Schwann cells in the nerve to an injury signal (activation of the Raf-TR) is remarkably different from those of control nerves. The high levels of proliferation in Merlin-null Schwann cells may be indicative of a higher tumorigenesis potential. While the proliferation of Merlin-null cells does reduce over time in the sciatic nerve, further experiments are now testing whether there may be ongoing tumour growth at other locations in the nervous system that are associated with NF2 tumours in human patients.

Activation of Raf signalling in NF2-null Schwann cells leads to sustained proliferation; an investigation of a new and inducible model for human schwannoma

Abstract Aims The NF2 gene encodes the tumour suppressor Merlin, which is deleted in 100% of patients with the familial tumour predisposition syndrome neurofibromatosis type 2 but also in 70% of those who develop sporadic schwannomas. The Raf-TR mouse model uses a tamoxifen-inducible Raf-kinase/ oestrogen receptor fusion protein (Raf-TR) expressed in myelinating Schwann cells to mimic a nerve injury response in Schwann cell by activating Raf/MEK/ERK signalling in the absence of peripheral nerve injury. We will assess whether Raf/MEK/ERK activation on an NF2 null background leads to tumourigenesis within the vestibular nerves and dorsal root ganglia (DRGs), two tumour sites identified in the Periostin-Cre mouse model in which schwannoma formation is spontaneous, with a view to generating an inducible NF2 null schwannoma mouse model. Method Mice with a Schwann cell specific loss of Merlin were crossed with mice carrying a tamoxifen-inducible Raf-TR gene to generate Raf-TR+/-; P0-Cre+/-; NF2fl/fl (Cre+) mice which were NF2 null and compared to Raf-TR+/-; P0-Cre-/-; NF2fl/fl (Cre-) littermate controls. Mice were injected with tamoxifen or vehicle for five consecutive days and their vestibular nerves and dorsal root ganglia (DRGs) were analysed at various timepoints . An EdU proliferation assay was used to quantify the proliferation in the vestibular ganglia, as well as the DRGs. Rates of proliferation were compared to Cre- age-matched littermate controls treated with tamoxifen or vehicle. Results In the Periostin-Cre NF2 null schwannoma model, tumours form spontaneously in the DRGs and vestibular ganglia. In our new model, we see a clear increase in proliferation at 21 d post-injection in the NF2 null (Cre+) tamoxifen-treated mice compared to control (Cre-) tamoxifen-treated controls in both DRGs and vestibular ganglia. Cre- tamoxifen-treated mice do not show increased proliferation compared to Cre- vehicle controls. Taken together, this shows that activation of the Raf/MEK/ERK pathway in Schwann cells only causes a sustained proliferation response on an NF2 null background in the DRGs and vestibular ganglia. We are assessing later timepoints to further characterise tumour development in these mice. Conclusion Combining the Raf-TR mouse model to create a demyelinating phenotype with an NF2 null background leads to vastly increased rates of proliferation at the sites of schwannoma tumourigenesis within the peripheral nervous system: the DRGs and the vestibular ganglia. The high proliferation in the vestibular ganglia in particular is similar to the development of vestibular schwannomas in patients with Neurofibromatosis type 2. The new mouse model used in this study shows potential to be very useful as an inducible schwannoma tumour model, in which we can study the early events of tumour formation.

Activation of MAPK/ERK signalling in Merlin-null Schwann cells leads to increased and sustained immune cell infiltration in the peripheral nervous system

Abstract Aims Previous work has shown that increased numbers of macrophages are associated with more rapid schwannoma tumour growth and we are interested in signals that control entry of macrophages and other immune cells into these tumours. Activation of the Raf-kinase domain and the Raf/MEK/ERK pathway within Schwann cells has been observed to induce an inflammatory response in peripheral nerves in the absence of injury. Activation of an inducible Raf-kinase transgene in Schwann cells allows modelling of acute demyelination of peripheral nerves without nerve injury. This Raf-oestrogen receptor fusion protein (Raf-TR) is activated by the oestrogen analogue Tamoxifen and so allows targeted, controlled activation of the Raf/MEK/ERK pathway within the Schwann cells. Here, in order to understand drivers of tumour formation, we assess the effect of MAPK activation in Merlin-null Schwann cells upon immune cell infiltration within the PNS. Method RafTR-P0CRE-NF2fl/fl mice of 4-6 weeks age were injected daily (IP) with 2mg of 4-hydroxy-tamoxifen or vehicle (corn oil) control for 5 consecutive days. RafTR was activated on either a Merlin (NF2) wild-type (NF2 fl/fl, P0-CRE-) or NF2 null (NF2 fl/fl, P0-CRE+) background and effects on immune cell infiltration studied in each condition. Immunofluorescence was performed in the dorsal root ganglia (DRGs) and sciatic nerves of mice to identify various immune cell infiltrates at various timepoints. These will include neutrophils, mast cells, T-Cells and macrophages using the cell markers Csf3r, C-kit, CD3 and IBA1 respectively. Results At 21 days post treatment, a significantly increased infiltration of macrophages within the sciatic nerve and dorsal root ganglia was observed in mice treated with Tamoxifen when compared to vehicle controls. Loss of NF2 led to a massive increase in the number of macrophages recruited to peripheral nerves in tamoxifen-treated mice compared to Cre- mice and Cre+ treated with vehicle alone. Further assessment of other immune cell infiltration including neutrophils, mast cells and T cells are ongoing. Conclusion Raf/MEK/ERK signalling, in the absence of tumour suppressor Merlin, significantly increases the infiltration of inflammatory cells such as macrophages into peripheral nerves even in the absence of injury. As this effect is enhanced in NF2 null mice, this suggests that Merlin plays an important role in inhibiting the inflammatory response in peripheral nerves. It also suggests that Merlin could be involved in maintaining the blood nerve barrier (BNB), as in its absence the greater influx of immune cells into the nerves and DRGs suggests a more complete loss of BNB function than just activation of the Raf/MEK/ERK cascade alone.

Correlation between Cranial Nerve Microstructural Characteristics and Vestibular Schwannoma Tumor Volume.

Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.

Sensitivity and Specificity of MRI in Intraspinal Tumor Patients

Background: Cancer is the leading cause of death worldwide, causing a global 10 million deaths just in 2018. Cancer has no cure, but is preventable if diagnosed early. Among the methods of diagnosing cancer, MRI or Magnetic Resonance Imaging is one of the most accurate ones. This study was done with the aim of evaluating the diagnostic usefulness of MRI in detection of intraspinal tumor and comparison with histopathological findings. Aim of the study: The study aimed to determine the sensitivity and specificity of MRI in respect to intraspinal tumor patients. Methods: The study was conducted at the Department of Radiology and Imaging, NITOR, Dhaka, Bangladesh, during the period of July 2019 to December 2020 with a sample size of 100 clinically suspected cases of intraspinal tumor aged between 10-70 years. Results: Among the participants, male: female ratio was 3:2. Thirty-Four (34) % of patients belonged to the age group of 41-50 years. 10% were from the youngest age group of 11-20 years, and 6% were from the oldest age group of 61-70 years. The mean age of the participants was 38.89 years. Weakness of the limbs was present in 92% of the participants, back pain was present in 90% percent of the participants. 58% of the participants had tumors in intradural extramedullary region. According to the MRI diagnosis, 55.56% of the participants had Sequestrated disc, 33.33% had Chronic Inflammatory lesion, and 11.11 % had Epidural abscess. According to the histopathological diagnosis of the patients, 32% had schwannoma tumors, 27% had meningioma tumors, 17% had ependymoma tumors, 5% had metastasis tumors, and 2% neurofibroma and hemangioma were present among the participants. After cross analysis of the MRI diagnosis with histopathological diagnosis, 76 cases were true positive, 2 cases were false positive, 6 cases were false negative and 16 cases were true negative. Sensitivity was found 92.68%, specificity was 88.88 % and accuracy was 82.60%. Conclusion: This study.......

Neurofibromatosis: Molecular Pathogenesis and Natural Compounds as Potential Treatments.

The neurofibromatosis syndromes, including NF1, NF2, and schwannomatosis, are tumor suppressor syndromes characterized by multiple nervous system tumors, particularly Schwann cell neoplasms. NF-related tumors are mainly treated by surgery, and some of them have been treated by but are refractory to conventional chemotherapy. Recent advances in molecular genetics and genomics alongside the development of multiple animal models have provided a better understanding of NF tumor biology and facilitated target identification and therapeutic evaluation. Many targeted therapies have been evaluated in preclinical models and patients with limited success. One major advance is the FDA approval of the MEK inhibitor selumetinib for the treatment of NF1-associated plexiform neurofibroma. Due to their anti-neoplastic, antioxidant, and anti-inflammatory properties, selected natural compounds could be useful as a primary therapy or as an adjuvant therapy prior to or following surgery and/or radiation for patients with tumor predisposition syndromes, as patients often take them as dietary supplements and for health enhancement purposes. Here we review the natural compounds that have been evaluated in NF models. Some have demonstrated potent anti-tumor effects and may become viable treatments in the future.

RNA-sequencing highlights differential regulated pathways involved in cell cycle and inflammation in orbitofacial neurofibromas.

Although most commonly benign, neurofibromas (NFs) can have devastating functional and cosmetic effects in addition to the possibility of malignant transformation. Orbitofacial NFs, in particular, may cause progressive, disfiguring tumors of the lid, brow, temple, face, and orbit, and clinical evidence suggests that they may have increased local aggressiveness compared to NFs developing at other sites. The purpose of this study was to identify biological differences between orbitofacial NFs and those occurring at other anatomic sites. We performed RNA‐sequencing in orbitofacial (n = 10) and non‐orbitofacial (n = 9) NFs. Differential gene expression analysis demonstrated that a variety of gene sets including genes involved in cell proliferation, interferon, and immune‐related pathways were enriched in orbitofacial NF. Comparisons with publicly available databases of various Schwann cell tumors and malignant peripheral nerve sheath tumor (MPNST) revealed a significant overlap of differentially expressed genes between orbitofacial versus non‐orbitofacial NF and plexiform NF versus MPNST. In summary, we identified gene expression differences between orbitofacial NF and NFs occurring at other locations. Further investigation may be warranted, given that orbitofacial NF are notoriously difficult to treat and associated with disproportionate morbidity.