Schwannomatosis: a genetic and epidemiological study

Natural history of hearing and tumor growth in vestibular schwannoma in neurofibromatosis type 2-related schwannomatosis

OBJECTIVES

To determine the natural history of hearing loss and tumor volume in patients with untreated neurofibromatosis type 2 (NF2)-related schwannomatosis. Moreover, we statistically examined the factors affecting hearing prognosis.

METHODS

This retrospective cohort study was conducted on 37 ears of 24 patients with NF2-related vestibular schwannomatosis followed up without treatment for more than 1 year. We obtained detailed chronological changes in the PTA and tumor volume in each case over time, and the rate of change per year was obtained. Multivariate analysis was also conducted to investigate factors associated with changes in hearing.

RESULTS

The average follow-up period was approximately 9 years, and hearing deteriorated at an average rate of approximately 4 dB/year. The rate of maintaining effective hearing decreased from 30 ears (81%) at the first visit to 19 ears (51%) at the final follow-up. The average rate of change in tumor growth for volume was approximately 686.0 mm3/year. This study revealed that most patients with NF2 experienced deterioration in hearing acuity and tumor growth during the natural course. A correlation was observed between an increase in tumor volume and hearing loss (r = 0.686; p < 0.001).

CONCLUSIONS

Although the hearing preservation rate in NF2 cases is poor with the current treatment methods, many cases exist in which hearing acuity deteriorates, even during the natural course. Patients with an increased tumor volume during the follow-up period were more likely to experience hearing deterioration. Trial registration number 20140242 (date of registration: 27 October 2014).

An unusual finding of an anaplastic meningioma in NF2-related schwannomatosis

NF2-related schwannomatosis (NF2) is a rare autosomal-dominant genetic disorder characterized by bilateral vestibular schwannomas and multiple meningiomas. This case report presents the extremely rare occurrence of an anaplastic meningioma in a 12-year-old male with previously undiagnosed NF2. The patient presented with a history of abdominal pain and episodic emesis, gait unsteadiness, right upper and lower extremity weakness, and facial weakness. He had sensorineural hearing loss and wore bilateral hearing aids. MR imaging revealed a sizable left frontoparietal, dural-based meningioma with heterogeneous enhancement with mass effect on the brain and midline shift. Multiple additional CNS lesions were noted including a homogenous lesion at the level of T5 indicative of compression of the spinal cord. The patient underwent a frontotemporoparietal craniotomy for the removal of his large dural-based meningioma, utilizing neuronavigation and transdural ultrasonography for precise en bloc resection of the mass. Histopathology revealed an anaplastic meningioma, WHO grade 3, characterized by brisk mitotic activity, small-cell changes, high Ki-67 proliferation rate, and significant loss of P16. We report an anaplastic meningioma associated with an underlying diagnosis of NF2 for which we describe clinical and histopathological features.

Case report of selumetinib as a novel therapy in a neurofibromatosis type 2-associated ependymoma

We report partial response (PR) to novel therapy with selumetinib in a patient with neurofibromatosis type 2 (NF2). A 25-year-old male presented with bilateral vestibular schwannomas, spinal cord intramedullary ependymomas, cranial and spinal meningiomas, spinal nerve root mixed schwannoma-neurofibromas, and peripheral nerve sheath tumors. He tested negative for germline NF2, SWItch/sucrose non-fermentable-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), and leucine zipper-like transcription regulator 1 (LZTR1) mutations. Molecular analysis of a resected cervical spine schwannoma-neurofibroma demonstrated an isolated somatic SMARCB1 mutation. Due to progression of all tumors, he was treated medically with both everolimus (10 mg/day) and selumetinib (25 mg/kg twice a day), but he rapidly transitioned to selumetinib monotherapy due to everolimus toxicity. 3 months of treatment resulted in PR in one spinal ependymoma and stable disease in other tumors. This PR was quantified by the differences in units of intensity in pre- and post-treatment magnetic resonance image. To the best of our knowledge, this is the first reported case for using selumetinib in NF2-associated tumors or ependymomas.

A Practical Guide to Sigma-1 Receptor Positron Emission Tomography/Magnetic Resonance Imaging: A New Clinical Molecular Imaging Method to Identify Peripheral Pain Generators in Patients with Chronic Pain

Accurately identifying the peripheral pain generator in patients with chronic pain remains a major challenge for modern medicine. Millions of patients around the world suffer endlessly from difficult-to-manage debilitating pain because of very limited diagnostic tests and a paucity of pain therapies. To help these patients, we have developed a novel clinical molecular imaging approach, and, in its early stages, it has been shown to accurately identify the exact site of pain generation using an imaging biomarker for the sigma-1 receptor and positron emission tomography/magnetic resonance imaging. We hope the description of the work in this article can help others begin their own pain imaging programs at their respective institutions.

Schwannomatosis: a Realm Reborn: year one

PURPOSE OF REVIEW

In 2022, an international consensus recommendation revised the nomenclature for neurofibromatosis type 2 ( NF2 ) and Schwannomatosis (SWN), now grouped under the umbrella term Schwannomatosis, and defined new diagnostic criteria.

RECENT FINDINGS

This review describes the molecular criteria for diagnosis of schwannomatosis and the subsequent diagnosis strategy, while setting out the most recent advances in our understanding of the natural history, pathology, molecular biology and treatment of schwannomatosis-associated tumors, including schwannomas, meningiomas and ependymomas.

SUMMARY

Somatic mutation screening should become a new standard for the diagnosis of NF2 -, LTZTR1 -, SMARCB1 - and 22q-schwannomatosis to discriminate those conditions. Constitutional events in NF2 -Schwannomatosis have a major influence on disease severity and justifiably motivate ongoing efforts on gene replacement therapy research. On the other hand, underlying mechanisms of disease severity and associated pain remain largely unknown in non- NF2 -SWN and independent of germline mutation. Research efforts therefore focus on pain relief in ongoing trials and the discovery of new molecular mechanisms underlying schwannoma tumorigenesis/pain/neuropathies.

Imaging and multi-omics datasets converge to define different neural progenitor origins for ATRT-SHH subgroups

Atypical teratoid rhabdoid tumors (ATRT) are divided into MYC, TYR and SHH subgroups, suggesting diverse lineages of origin. Here, we investigate the imaging of human ATRT at diagnosis and the precise anatomic origin of brain tumors in the Rosa26-CreERT2::Smarcb1flox/flox model. This cross-species analysis points to an extra-cerebral origin for MYC tumors. Additionally, we clearly distinguish SHH ATRT emerging from the cerebellar anterior lobe (CAL) from those emerging from the basal ganglia (BG) and intra-ventricular (IV) regions. Molecular characteristics point to the midbrain-hindbrain boundary as the origin of CAL SHH ATRT, and to the ganglionic eminence as the origin of BG/IV SHH ATRT. Single-cell RNA sequencing on SHH ATRT supports these hypotheses. Trajectory analyses suggest that SMARCB1 loss induces a de-differentiation process mediated by repressors of the neuronal program such as REST, ID and the NOTCH pathway.

Neurofibromatosis- and schwannomatosis-associated tumors: Approaches to genetic testing and counseling considerations

Neurofibromatosis (NF) and schwannomatosis (SWN) are genetic conditions characterized by the risk of developing nervous system tumors. Recently revised diagnostic criteria include the addition of genetic testing to confirm a pathogenic variant, as well as to detect the presence of mosaicism. Therefore, the use and interpretation of both germline and tumor-based testing have increasing importance in the diagnostic approach, treatment decisions, and risk stratification of these conditions. This focused review discusses approaches to genetic testing of NF- and SWN-related tumor types, which are somewhat rare and perhaps lesser known to non-specialized clinicians. These include gastrointestinal stromal tumors, breast cancer, plexiform neurofibromas with or without transformation to malignant peripheral nerve sheath tumors, gliomas, and schwannomas, and emphasizes the need for inclusion of genetic providers in patient care and appropriate pre- and post-test education, genetic counseling, and focused evaluation by a medical geneticist or other healthcare provider familiar with clinical manifestations of these disorders.

[Neurofibromatosis type 1 associated with pheochromocytoma: a case report with a brief review of the literature]

We presented the clinical case of neurofibromatosis type 1 (NF-1) associated with pheochromocytoma (PHEO) in a man under 40 years old without family history. The diagnosis of NF-1 was established based on 4 signs of the disease (multiple café au lait macules, scoliotic changes in posture, the presence of multiple neurofibromas, Lisch nodules). The diagnosis of PHEO was determined by a significant increase of free metanephrin/normethanephrin levels in daily urine, a malignant CT phenotype of the right adrenal tumor, and confirmed by pathomorphological study. Genetic tests revealed a new mutation in one of the alleles of NF1 gene, a deletion of a 566 bp gene fragment, including exon 19 with a size of 73 bp. This mutation leads to splicing of exons 18 and 20, frameshift, and termination of protein synthesis. A study of the level of transcription of the genes associated with PHEO (RET, TMEM127, MAX, FGFR, MET, MERTK, BRAF, NGFR, Pi3, AKT, MTOR, KRAS, MAPK) was conducted, a statistically significant decrease in the level of transcription of the KRAS and BRAF genes and increase in the level of transcription of the TMEM127 gene in comparison with control samples have been detected. This case demonstrates the need for timely recognition of NF-1 for further appropriate patient's follow up and show the effectiveness of a multidisciplinary approach to the diagnosis and treatment of NF-1-associated catecholamine-secreting tumors.

Differential rates of germline heterozygote and mosaic variants in NF2 may show varying propensity for meiotic or mitotic mutation

NF2-related schwannomatosis is an autosomal dominant tumour predisposition condition that causes multiple benign tumours of the nervous system, especially schwannomas. This results from germline pathogenic variants in the NF2 gene, which are most commonly de novo NF2 nonsense variants. Over half of these de novo variants occur at just six CpG dinucleotides. In this study, we show that the six NF2 CpG nonsense variants make up 54% (136/252) of de novo nonsense variants, despite constituting <10% of nonsense positions in the germline (total=62), and that this pattern is different from the APC gene, which is also known to have a high rate of mosaicism. In addition, the NF2 c.586C>T; p.(Arg196Ter) has a higher de novo heterozygote to mosaicism ratio than the five other CpG variants (73.1% vs 53.7%, p=0.03) and the neighbouring CpG variant (NF2 c.592C>T; p.(Arg198Ter) 38.5%, p=0.02). This may be due to differences in rates of mutation at meiosis versus mitosis.

Intradural Extramedullary Tumors and Associated Syndromes

Most intradural tumors are located within the intradural extramedullary compartment, and the most common tumors are schwannomas and meningiomas. Other less common neoplasms include neurofibroma, solitary fibrous tumor, myxopapillary ependymoma, lymphoma, metastatic leptomeningeal disease, malignant peripheral nerve sheath tumor, and paraganglioma. Patients usually present with gait ataxia, radicular pain, and motor and sensory deficits due to chronic compressive myelopathy or radiculopathy. MRI is the modality of choice for detecting and evaluating intradural extramedullary spinal tumors. This imaging technique helps narrow the differential diagnosis and therefore decide treatment.

Risk factors for intraoperative hemorrhage of Type I neurofibromatosis

INTRODUCTION

Neurofibromatosis (NF) is an inherited disease and a benign tumor originating from nerve sheath cells. Neurofibromatosis type I (NF1) is the most common type, and most cases are characterized by neurofibromas. Neurofibromas in NF1 are mainly treated by surgery. Our study explores the risk factors for intraoperative hemorrhage in Type I neurofibromatosis patients who underwent neurofibroma resection.

METHODS

A cross-sectional comparison of the patients who had undergone resection of neurofibroma for NF1. Data regarding patient characteristics and data about operative outcomes were recorded. The definition of intraoperative hemorrhage group was the intraoperative blood loss greater than 200 ml.

RESULTS

Of 94 eligible patients, 44 patients were in the hemorrhage group and 50 patients were in the non-hemorrhage group. Multiple logistic regression analysis demonstrated that the area of excision, classification, surgical site, primary surgical, and organ deformation were significant independent predictors of hemorrhage.

CONCLUSION

Early treatment can reduce the tumor cross-sectional area, avoid organ deformation, and reduce intraoperative blood loss. For plexiform neurofibroma or neurofibroma of the head and face, the amount of blood loss should be predicted correctly, and preoperative evaluation and blood preparation should be paid more attention to.

Correlation between genotype and phenotype with special attention to hearing in 14 Japanese cases of NF2-related schwannomatosis

NF2-related schwannomatosis (NF2) is an autosomal dominant genetic disorder caused by variants in the NF2 gene. Approximately 50% of NF2 patients inherit pathogenic variants, and the remainder acquire de novo variants. NF2 is characterized by development of bilateral vestibular schwannomas. The genetic background of Japanese NF2 cases has not been fully investigated, and the present report performed a genetic analysis of 14 Japanese NF2 cases and examined genotype-phenotype correlations. DNA samples collected from peripheral blood were analyzed by next-generation sequencing, multiplex ligation-dependent probe amplification analysis, and in vitro electrophoresis. Ten cases had pathogenic or likely pathogenic variants in the NF2 gene, with seven truncating variants and three non-truncating variants. The age of onset in all seven cases with truncating variants was < 20 years. The age of onset significantly differed among cases with truncating NF2 variants, non-truncating NF2 variants, and no NF2 variants. However, the clinical course of tumor growth and hearing deterioration were not predicted only by germline pathogenic NF2 variants. The rate of truncating variants was higher in the present study than that of previous reports. Genotype-phenotype correlations in the age of onset were present in the analyzed Japanese NF2 cases.

LZTR1 Mutation Mediates Oncogenesis through Stabilization of EGFR and AXL

LZTR1 is the substrate-specific adaptor of a CUL3-dependent ubiquitin ligase frequently mutated in sporadic and syndromic cancer. We combined biochemical and genetic studies to identify LZTR1 substrates and interrogated their tumor-driving function in the context of LZTR1 loss-of-function mutations. Unbiased screens converged on EGFR and AXL receptor tyrosine kinases as LZTR1 interactors targeted for ubiquitin-dependent degradation in the lysosome. Pathogenic cancer-associated mutations of LZTR1 failed to promote EGFR and AXL degradation, resulting in dysregulated growth factor signaling. Conditional inactivation of Lztr1 and Cdkn2a in the mouse nervous system caused tumors in the peripheral nervous system including schwannoma-like tumors, thus recapitulating aspects of schwannomatosis, the prototype tumor predisposition syndrome sustained by LZTR1 germline mutations. Lztr1- and Cdkn2a-deleted tumors aberrantly accumulated EGFR and AXL and exhibited specific vulnerability to EGFR and AXL coinhibition. These findings explain tumorigenesis by LZTR1 inactivation and offer therapeutic opportunities to patients with LZTR1-mutant cancer.

SIGNIFICANCE

EGFR and AXL are substrates of LZTR1-CUL3 ubiquitin ligase. The frequent somatic and germline mutations of LZTR1 in human cancer cause EGFR and AXL accumulation and deregulated signaling. LZTR1-mutant tumors show vulnerability to concurrent inhibition of EGFR and AXL, thus providing precision targeting to patients affected by LZTR1-mutant cancer. This article is highlighted in the In This Issue feature, p. 517.

Co-Targeting IL-6 and EGFR signaling for the treatment of schwannomatosis and associated pain

Patients with Schwannomatosis (SWN) overwhelmingly present with intractable, debilitating chronic pain. There are no effective therapies to treat SWN. The drivers of pain response and tumor progression in SWN are not clear. The pain is not proportionally linked to tumor size and is not always relieved by tumor resection, suggesting that mechanisms other than mechanical nerve compression exist to cause pain. SWN research is limited by the lack of clinically-relevant models. Here, we established novel patient-derived xenograft (PDX) models, dorsal root ganglia (DRG) imaging model, and combined with single-cell resolution intravital imaging and RNASeq, we discovered: i) schwannomas on the peripheral nerve cause macrophage influx into the DRG, via secreting HMGB1 to directly stimulate DRG neurons to express CCL2, the key macrophage chemokine, ii) once recruited, macrophages cause pain response via overproduction of IL-6, iii) IL-6 blockade in a therapeutic setting significantly reduces pain but has modest efficacy on tumor growth, iv) EGF signaling is a potential driver of schwannoma growth and escape mechanism from anti-IL6 treatment, and v) combined IL-6 and EGFR blockade simultaneously controlled pain and tumor growth in SWN models. Our findings prompted the initiation of phase II clinical trial ( NCT05684692 ) for pain relief in patients with SWN.

COVID-19 in people with neurofibromatosis 1, neurofibromatosis 2, or schwannomatosis

PURPOSE

People with pre-existing conditions may be more susceptible to severe COVID-19 when infected by SARS-CoV-2. The relative risk and severity of SARS-CoV-2 infection in people with rare diseases such as neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), or schwannomatosis (SWN) is unknown.

METHODS

We investigated the proportions of people with NF1, NF2, or SWN in the National COVID Cohort Collaborative (N3C) electronic health record data set who had a positive test result for SARS-CoV-2 or COVID-19.

RESULTS

The cohort sizes in N3C were 2501 (NF1), 665 (NF2), and 762 (SWN). We compared these with N3C cohorts of patients with other rare diseases (98-9844 individuals) and the general non-NF population of 5.6 million. The site- and age-adjusted proportion of people with NF1, NF2, or SWN who had a positive test result for SARS-CoV-2 or COVID-19 (collectively termed positive cases) was not significantly higher than in individuals without NF or other selected rare diseases. There were no severe outcomes reported in the NF2 or SWN cohorts. The proportion of patients experiencing severe outcomes was no greater for people with NF1 than in cohorts with other rare diseases or the general population.

CONCLUSION

Having NF1, NF2, or SWN does not appear to increase the risk of being SARS-CoV-2 positive or of being a patient with COVID-19 or of developing severe complications from SARS-CoV-2.

Hemorrhagic schwannoma of the trochlear nerve: Case report and a review of the literature

Background

Schwannomas of the trochlear nerve with the absence of systemic neurofibromatosis are considerably uncommon, especially complicated by intra-tumoral hemorrhage. Due to the lack of typical clinical manifestations and imaging findings, a definite diagnosis of trochlear schwannomas before surgery is particularly difficult.

Case presentation

We report the case of a 64-year-old female patient who presented with a unilaterally intermittent headache of 2-month duration and without a remarkable neurological deficit at admission. Imaging studies revealed a well-demarcated cystic-solid lesion with mixed signals beside the brainstem and suprasellar cisterna. The patient underwent a surgical operation with total resection of the tumor by a subtemporal surgical approach. The tumor was intraoperatively found to originate from the trochlear nerve and was pathologically confirmed as a hemorrhagic schwannoma with cystic degeneration.

Conclusions

We describe this case in detail and conduct a concomitant survey of the literature, summarizing the clinical presentations, radiological features, surgical treatment, and the possible mechanisms of hemorrhage in relevance to trochlear nerve schwannoma.

A Rare Case of Familial Schwannomatosis Showing Intrafamilial Variability with Identification of a Shared Novel Germline SMARCB1 Mutation

Schwannomatosis is characterized by the presence of multiple schwannomas without landmarks of NF2. It is considered the rarest form of neurofibromatosis (NF). Here, we report the first case of familial schwannomatosis with regard to the segmental/generalized phenotype, in which the proband and the daughter present a distinct phenotype in this classification. The proband presents a generalized, painless, extradural type of schwannomatosis, while the daughter shows a segmental, painful, intradural type of schwannomatosis. Whole-exome sequencing of the affected individuals revealed a shared novel SMARCB1 gene mutation (c.92A > G, p.Glu31Gly) despite the clinical variability. We thus suggest two points in the diagnosis of familial schwannomatosis: The identified novel germline SMARCB1 variant can be reflective of a phenotypical progression from a segmental to a generalized type of schwannomatosis, or an intrafamilial variability in inherited schwannomatosis, which was not reported in previous literature. The specific combination of somatic NF2 mutations may be a major factor in regulating the severity and scope of the resulting phenotype in schwannomatosis.

Design of a randomized, placebo-controlled, phase 2 study evaluating the safety and efficacy of tanezumab for treatment of schwannomatosis-related pain

BACKGROUND

Schwannomatosis (SWN) is a rare tumor suppressor syndrome that predisposes affected individuals to develop multiple schwannomas and, less often, meningiomas. The most common symptom is chronic, severe pain. No medications are broadly effective in treating SWN-associated pain. The clinical trial described in this manuscript is a phase 2, randomized, double-blind, placebo-controlled study investigating the safety and efficacy of tanezumab - a humanized monoclonal antibody that inhibits nerve growth factor - for treatment of SWN-related pain. As the first therapeutic trial for SWN-related pain, it also aims to evaluate trial endpoints, understand recruitment patterns, and improve clinical trial design in this rare disease.

AIMS

The primary objective of this trial is to assess the analgesic efficacy of subcutaneous tanezumab 10 mg in subjects with SWN who continue pre-existing pain therapy (excluding non-steroidal anti-inflammatory drugs). The secondary objective is to assess safety in this population. Exploratory objectives include assessment of pain features, quality of life, and predictive biomarkers.

METHODS

The study is comprised of four periods (pre-treatment, double-blind treatment, single-arm treatment, safety follow-up) across 10 months with a delayed-start trial design to allow all participants to receive tanezumab. Forty-six participants will be enrolled and randomized 1:1 to receive either tanezumab or placebo subcutaneously in the double-blind treatment period; all participants receive tanezumab during the single-arm treatment period.

CONCLUSIONS

This study is the first therapeutic trial for SWN patients and targets a biological driver of SWN-related pain. It aims to establish a model for future pain studies in SWN and other rare diseases.

CLINICAL TRIAL REGISTRATION

NCT04163419 on ClinicalTrials.gov.

Understanding barriers to diagnosis in a rare, genetic disease: Delays and errors in diagnosing schwannomatosis

Diagnosis of rare, genetic diseases is challenging, but conceptual frameworks of the diagnostic process can guide quality improvement initiatives. Using the National Academy of Medicine diagnostic framework, we assessed the extent of, and reasons for diagnostic delays and diagnostic errors in schwannomatosis, a neurogenetic syndrome characterized by nerve sheath tumors and chronic pain. We reviewed the medical records of 97 people with confirmed or probable schwannomatosis seen in two US tertiary care clinics. Time-to-event analysis revealed a median time from first symptom to diagnosis of 16.7 years (95% CI, 7.5-26.0 years) and median time from first medical consultation to diagnosis of 9.8 years (95% CI, 3.5-16.2 years). Factors associated with longer times to diagnosis included initial signs/symptoms that were intermittent, non-specific, or occurred at younger ages (p < 0.05). Thirty-six percent of patients were misdiagnosed; misdiagnoses were of underlying genetic condition (18.6%), pain etiology (16.5%), and nerve sheath tumor presence/pathology (11.3%) (non-mutually exclusive categories). One-fifth (19.6%) of patients had a clear missed opportunity for genetics workup that could have led to an earlier schwannomatosis diagnosis. These results suggest that interventions in clinician education, genetic testing availability, expert review of pathology findings, and automatic triggers for genetics referrals may improve diagnosis of schwannomatosis.

A Systematic Review of Recent and Ongoing Clinical Trials in Patients With the Neurofibromatoses

INTRODUCTION

The neurofibromatoses comprise three different genetic conditions causing considerable morbidity and mortality: neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN). This review summarizes recent and ongoing clinical trials involving patients with neurofibromatoses to better understand the current state of clinical trial research centered around these conditions and inform areas of need.

METHODS

A search was conducted using the Cochrane Central Register of Controlled Trials and clinicaltrials.gov databases. Inclusion and exclusion criteria were designed to identify clinical trials focused on patients with NF1, NF2, or SWN completed in or after 2010 and in process as of December 31, 2021. Information was collected using standardized guidelines.

RESULTS

A total of 134 clinical trials were included, with 75 (56%) completed and 59 (44%) in process. For completed trials, 74% (n = 56) involved patients with NF1, and of those based on specific tumors (n = 26, 46%), the majority focused on plexiform neurofibromas (PNs) (n = 12, 46%). For ongoing trials, 79% (n = 47) involve patients with NF1, and of those based on specific tumors (n = 29, 61%), the majority are focused on PNs (n = 13, 45%).

CONCLUSION

Both recent and ongoing clinical trials have primarily focused on patients with NF1 and the treatment of PNs. This research has led to the first FDA-approved drug for NF1-PN and has changed management of these tumors, allowing for systemic therapy rather than reliance on only a surgical modality. Trials evaluating comorbid psychiatric conditions and quality of life among patients with any of the neurofibromatoses appear less common. These areas may warrant focus in future studies to improve clinical management.

Laparoscopic retroperitoneal resection of the duodenal gastrointestinal stromal tumors in neurofibromatosis type 1; Case Report and literature review

Background

Neurofibromatosis type 1, also known as NF1, is a disorder that is passed down in an autosomal dominant manner. It manifests in a wide variety of tumors and affects several organ systems. It is expected that those carrying the NF1 gene will develop a rare mesenchymal tumor known as a gastrointestinal stromal tumor (GIST) more than general population.

Case report

This research discusses a 42-year-old female patient with NF1 who was identified with a duodenal GIST but clinically and radiographically misinterpreted as having a retroperitoneal neurofibroma. She had minimally invasive retroperitoneal laparoscopic surgery to remove the tumor and primary anastomosis of the affected duodenal wall. A spindle cell GIST was entirely excised during surgery, as indicated by the pathologist. As a consequence of dialogue at a multidisciplinary team meeting, the patient was discharged from the hospital on the fourth postoperative day and is presently undergoing regular clinical follow-up.

Conclusion

Anatomically problematic sites, such as the duodenal GIST in NF1 patients, can be treated safely with the laparoscopic retroperitoneal approach even when retroperitoneal neoplasia arises from the intrabdominal structure and protrudes into the retroperitoneal region.

Benign Peripheral Non-cranial Nerve Sheath Tumors of the Neck

Benign peripheral non-cranial nerve sheath tumors are rare lesions, including both schwannomas and neurofibromas. These tumors arise from Schwann cells, and may originate from any peripheral, cranial, or autonomic nerve. Most of them are localized and sporadic but multifocal systemic forms can occur. Cervical sympathetic chain, brachial plexus, cervical plexus and spinal roots and nerves are the major nerve systems commonly affected. Dumbbell-shaped intra- and extradural tumors occur most commonly in the cervical spine, as well as purely extradural and paravertebral tumors. The management of these tumors has improved greatly owing to the developments in imaging techniques and surgical innovations such as endoscopically assisted approaches and robotic surgery. Microsurgical intracapsular excision of the tumor helped by the use of intraoperative fluorescent dyes and intraoperative neurophysiological monitoring minimize postoperative neural deficit, since most schwannomas are encapsulated. Most tumors can be removed with a low rate of complications and recurrence. Radiotherapy should be considered for growing lesions that are not amenable to surgery. In asymptomatic patients, observation and serial scans is an option for elderly infirm patients.

Schwannomatosis patient who was followed up for fifteen years: A case report

BACKGROUND

Schwannomatosis is a rare disease characterized by multiple schwannomas of the whole body. Although benign, schwannomatosis that occurs in important areas of the body, such as the brain and spinal canal, can cause considerable disability and mortality. The disease is rare, frequent and relapsing, and this poses a diagnostic and therapeutic challenge.

CASE SUMMARY

A 40-year-old male had multiple masses all over his body, starting at the age of 19. Four years prior, he started to experience a progressive decrease in muscle strength in both lower limbs and developed urinary and defecation dysfunctions, and gradual paralysis. One month prior, the patient developed pain and numbness in his left forearm. The patient had undergone five surgical procedures for this disease in our department. Based on the family history, imaging examinations, pathological biopsy and molecular biological examinations, the diagnosis of schwannomatosis was confirmed. This time, the patient was admitted to our hospital again for a 6th operation because of the pain and numbness in his left forearm. After the operation, the patient's symptoms improved significantly; the patient recovered and was discharged from the hospital. At the last telephone follow-up, the patient reported a poor general condition but was alive.

CONCLUSION

Here, we report a rare case of schwannomatosis. We conducted 15 years of patient follow-up and treatment, and analyzed the timing of surgery and patient psychology. This case will further extend our overall understanding of the diagnosis and treatment of this rare tumor.

Bibliometric analysis of the top 100 most-cited articles in neurofibromatosis

Background:

Neurofibromatosis (NF) is an umbrella term that refers to three distinct disease entities: NF Type 1, Type 2, and schwannomatosis. Here, we reviewed the scientific performance and the most influential publications on NF.

Methods:

A keyword-based search was performed using the Scopus database. The top 100 articles were grouped based on NF types and the studied entities. The differences between the articles, authors, and journals were quantified based on certain parameters. Other parameters were collected for the complete citational analysis.

Results:

The top 100 articles were published between 1961 and 2020. The most trending period of research was in the 1990s and articles studying the clinical aspect and the underlying genetic correlation made up 84% of all articles from the list. The United States of America (USA) had the highest number of contributions (69 articles, 69%). The top institute of contribution to the list was the Howard Hughes Medical Institute, USA (14 articles, 14%). Author-based analysis reveals that the neurologist D. H. Gutmann from St. Louis Children’s Hospital, USA, was the most active and authored 11 articles (11%) on the list.

Conclusion:

The publication trends show that articles studying medical and surgical management were of little interest. The top 100 articles did not include any randomized control trials, and the highest level of evidence was obtained from reviews of pooled knowledge as well as population-based and longitudinal studies.

ERN GENTURIS clinical practice guidelines for the diagnosis, treatment, management and surveillance of people with schwannomatosis

A Guideline Group (GG) was convened from multiple specialties and patients to develop the first comprehensive schwannomatosis guideline. The GG undertook thorough literature review and wrote recommendations for treatment and surveillance. A modified Delphi process was used to gain approval for recommendations which were further altered for maximal consensus. Schwannomatosis is a tumour predisposition syndrome leading to development of multiple benign nerve-sheath non-intra-cutaneous schwannomas that infrequently affect the vestibulocochlear nerves. Two definitive genes (SMARCB1/LZTR1) have been identified on chromosome 22q centromeric to NF2 that cause schwannoma development by a 3-event, 4-hit mechanism leading to complete inactivation of each gene plus NF2. These genes together account for 70-85% of familial schwannomatosis and 30-40% of isolated cases in which there is considerable overlap with mosaic NF2. Craniospinal MRI is generally recommended from symptomatic diagnosis or from age 12-14 if molecularly confirmed in asymptomatic individuals whose relative has schwannomas. Whole-body MRI may also be deployed and can alternate with craniospinal MRI. Ultrasound scans are useful in limbs where typical pain is not associated with palpable lumps. Malignant-Peripheral-Nerve-Sheath-Tumour-MPNST should be suspected in anyone with rapidly growing tumours and/or functional loss especially with SMARCB1-related schwannomatosis. Pain (often intractable to medication) is the most frequent symptom. Surgical removal, the most effective treatment, must be balanced against potential loss of function of adjacent nerves. Assessment of patients' psychosocial needs should be assessed annually as well as review of pain/pain medication. Genetic diagnosis and counselling should be guided ideally by both blood and tumour molecular testing.

Laminectomy triggers symptomatic growth of spinal schwannoma in a patient with schwannomatosis

Background:

Schwannomatosis (SWN) is genetically similar to neurofibromatosis type 2 (NF2) and represents a NF2 gene mutation. Previous studies have shown that these mutations in both neurons and Schwann cells can lead to the development of schwannomas after nerve crush injuries. Here, we reviewed the potential pathoanatomical mechanisms for the development of a trauma-induced spinal schwannomas in a 55-year-old male with SWN.

Case Description:

A 49-year-old male had originally undergone a L3–L5 lumbar laminectomy for stenosis; the schwannomas seen on the preoperative magnetic resonance imaging (MRI) were not resected. Now at age 55, he newly presented with low back pain and numbness in the left L5 dermatome, and he was diagnosed with an L4 vertebral level cauda equina tumor on MRI. Following gross-total resection, the histopathological assessment revealed a Ki-67 labeling index 5–10% in hotspots (i.e., slightly higher than the normal range of schwannomas) and a 20% mosaic loss of SMARCB1. Based on these criteria, he was diagnosed as having SWN.

Conclusion:

In this patient with SWN, compression/physical trauma to nerves of the cauda equina during the L3–L5 laminectomy 6 years ago likely caused the progression of schwannoma.

Dermatologic manifestations in paediatric neurofibromatosis type 2: a cross sectional descriptive multicentric study

Background

Neurofibromatosis type 2 (NF2) is characterized by bilateral vestibular schwannoma (VS) more often in adults but a severe paediatric form with multiple neurological tumours is also described. In this population, a early diagnosis is important to prevent the onset of neurological complications but is difficult, particularly without a familial history. Cutaneous manifestations, which may precede VS or neurological tumours by several years, may contribute to an early diagnosis, but specific studies are lacking. The objective of this study was to characterize cutaneous manifestations of NF2 in a paediatric population.

Results

This observational, descriptive and multicentric study was conducted from April 2019 to April 2020 in seven academic French hospitals. We included patients ≤ 18 years old who fulfilled the Manchester diagnostic criteria or had a pathogenic mutation identified in the NF2 gene. All patients underwent a dermatological examination guided by a standardized questionnaire. 21 children were included, of whom 20 had at least one skin tumour (mean number 5 ± 4.6 [range 0–15]), which led to a diagnosis in four cases. In the other 17 cases, the diagnosis of NF2 was based on neurosensory complications (n = 10), family screening (n = 4) or ocular signs (n = 3). Before the NF2 diagnosis, 15 children had at least one “undiagnosed” cutaneous tumour that did not lead to a specific management. Patients’ dermatological examination also revealed < 6 non specific café au lait macules (n = 15), hypopigmented macules (n = 12) with more than 3 lesions in 4 cases, and purple reticulated macules of the trunk (n = 4).

Conclusion

Dermatological lesions are frequent and early in children with NF2 but rarely lead to the diagnosis. Cutaneous schwannomas are the most frequent but are often underdiagnosed. Café au lait macules are frequent, but atypical and mostly in small numbers. Multiple hypopigmented macules seem suggestive although inconsistent. The sensitivity of reticulated capillary malformation-like lesions remains to be assessed by further studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02379-6.

Screening of potential novel candidate genes in schwannomatosis patients

Schwannomatosis comprises a group of hereditary tumor predisposition syndromes characterized by, usually benign, multiple nerve sheath tumors, which frequently cause severe pain that does not typically respond to drug treatments. The most common schwannomatosis‐associated gene is NF2, but SMARCB1 and LZTR1 are also associated. There are still many cases in which no pathogenic variants (PVs) have been identified, suggesting the existence of as yet unidentified genetic risk factors. In this study, we performed extended genetic screening of 75 unrelated schwannomatosis patients without identified germline PVs in NF2, LZTR1, or SMARCB1. Screening of the coding region of DGCR8, COQ6, CDKN2A, and CDKN2B was carried out, based on previous reports that point to these genes as potential candidate genes for schwannomatosis. Deletions or duplications in CDKN2A, CDKN2B, and adjacent chromosome 9 region were assessed by multiplex ligation‐dependent probe amplification analysis. Sequencing analysis of a patient with multiple schwannomas and melanomas identified a novel duplication in the coding region of CDKN2A, disrupting both p14ARF and p16INK4a. Our results suggest that none of these genes are major contributors to schwannomatosis risk but the possibility remains that they may have a role in more complex mechanisms for tumor predisposition.

Clinical characteristics and genetic testing outcome of suspected hereditary peripheral nerve sheath tumours in a tertiary cancer institution in Singapore

Background

Peripheral Nerve Sheath Tumors (PNST) are a diverse group of mostly benign tumours uncommon in the general population. About 5–10% of PNSTs are hereditary, predominantly arising from germline variants in NF1, NF2, SMARCB1, or LZTR1 gene.

Methods

We reviewed the clinical characteristics and genetic testing results of patients referred to the NCIS Adult Cancer Genetics Clinic for suspected hereditary PNST.

Results

3,001 patients suspected to have various hereditary cancer syndromes were evaluated between year 2000 to March 2021. 13 (0.4%) were clinically diagnosed to have hereditary PNSTs. The majority were male (54%), with a median age at presentation to the genetics clinic of 29 years (range 19–48). 11/13 (85%) patients had multiple PNSTs, 12/13 (92%) had young onset PNSTs, 5/13 (38.5%) had personal and family history of PNST. 11/13 patients (85%) had clinical features of neurofibromatosis type 1 (NF1) including one patient who also fulfilled clinical criteria of neurofibromatosis type 2 (NF2); 2/13 (14%) had multiple schwannomas. Four patients underwent multi-gene panel testing, including one patient with clinical NF1, one patient who met both clinical NF1 and NF2 criteria, and two patients with multiple schwannomas. The patient with clinical features of NF1 was heterozygous for a pathogenic c. 2033dup variant in the NF1 gene. The patient with both NF1/NF2 features was heterozygous for a novel c.732 T > A nonsense variant in the NF2 gene. The two patients with multiple schwannomas were heterozygous for a pathogenic/likely pathogenic variant in the LZTR1 gene and are the first LZTR1-positive schwannomatosis patients reported in Asia.

Conclusion

Hereditary PNSTs are rare referrals to an adult cancer genetics clinic. NF1 is the most common PNST seen. LZTR1 variants may be the underlying cause in Asian patients with multiple schwannomatosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13053-022-00230-4.

Updated diagnostic criteria and nomenclature for neurofibromatosis type 2 and schwannomatosis: An international consensus recommendation

PURPOSE

Neurofibromatosis type 2 (NF2) and schwannomatosis (SWN) are genetically distinct tumor predisposition syndromes with overlapping phenotypes. We sought to update the diagnostic criteria for NF2 and SWN by incorporating recent advances in genetics, ophthalmology, neuropathology, and neuroimaging.

METHODS

We used a multistep process, beginning with a Delphi method involving global disease experts and subsequently involving non-neurofibromatosis clinical experts, patients, and foundations/patient advocacy groups.

RESULTS

We reached consensus on the minimal clinical and genetic criteria for diagnosing NF2 and SWN. These criteria incorporate mosaic forms of these conditions. In addition, we recommend updated nomenclature for these disorders to emphasize their phenotypic overlap and to minimize misdiagnosis with neurofibromatosis type 1.

CONCLUSION

The updated criteria for NF2 and SWN incorporate clinical features and genetic testing, with a focus on using molecular data to differentiate the 2 conditions. It is likely that continued refinement of these new criteria will be necessary as investigators study the diagnostic properties of the revised criteria and identify new genes associated with SWN. In the revised nomenclature, the term "neurofibromatosis 2" has been retired to improve diagnostic specificity.

RETRACTED: A case report of a 4-year-old girl with neurofibromatosis type 1

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Authors. A diagnostic discordance in the original pathology reports has been noticed and requires further evaluation, therefore the paper will be retracted.

WP1066 induces cell death in a schwannomatosis patient-derived schwannoma cell line

Schwannomatosis is a rare genetic disorder that predisposes individuals to development of multiple schwannomas mainly in spinal and peripheral nerves and to debilitating chronic pain often unrelated to any schwannoma. Pathogenic variants of two genes, SMARCB1 and LZTR1, are causal in familial cases. However, many schwannomatosis patients lack mutations in these genes. Surgery is the standard treatment for schwannomas but leaves patients with increasing neurological deficits. Pain management is a daily struggle controlled by the use of multiple analgesic and anti-inflammatory drugs. There is a need for both nonsurgical treatment to manage tumor growth and nonaddictive, nonsedative pain control. Because standard clinical trials are exceedingly difficult for patients with rare disorders, precision medicine approaches offer the possibility of bespoke therapeutic regimens to control tumor growth. As a proof of principle, we obtained a bio-specimen of paraspinal schwannoma from a schwannomatosis patient with a germline point mutation in the SMARCB1/INI gene. We created an hTERT immortalized cell line and tested the ability of targeted small molecules with efficacy in neurofibromatosis type 2-related schwannomas to reduce cell viability and induce cell death. We identified WP1066, a STAT3 inhibitor, currently in phase 2 clinical trials for pediatric and adult brain tumors as a lead compound. It reduced cell viability and STAT-3 phosphorylation and induced expression of markers for both necroptosis and caspase-dependent cell death. The results demonstrate feasibility in creating patient-derived cell lines for use in precision medicine studies.

Primary Benign Tumors of the Spinal Canal

Benign tumors that grow in the spinal canal are heterogeneous neoplasms with low incidence; from these, meningiomas and nerve sheath tumors (neurofibromas and schwannomas) account for 60%-70% of all primary spinal tumors. Benign spinal canal tumors provoke nonspecific clinical manifestations, mostly related to the affected level of the spinal cord. These tumors present a challenge for the patient and healthcare professionals, for they are often difficult to diagnose and the high frequency of posttreatment complications. In this review, we describe the epidemiology, risk factors, clinical features, diagnosis, histopathology, molecular biology, and treatment of extramedullary benign meningiomas, osteoid osteomas, osteoblastomas, aneurysmal bone cysts, osteochondromas, neurofibromas, giant cell tumors of the bone, eosinophilic granulomas, hemangiomas, lipomas, and schwannomas located in the spine, as well as possible future targets that could lead to an improvement in their management.

Hereditary intraspinal schwannomatosis with SMARCB1 gene mutation: A case report

Background

Schwannomatosis is the third subtype of neurofibromatosis. Schwannomatosis, particularly the familial variant, is uncommon. Recently, germline mutations of the SMARCB1 gene have been found to cause schwannomatosis. In this report, we describe a case of familial inherited intraspinal schwannomatosis. Postoperative pathology indicated a schwannoma. The results of gene testing showed that the SMARCB1 gene had a spliced mutation.

Case description

A patient with a rare case of familial intraluminal schwannomatosis was admitted to our hospital. Peripheral blood gene testing was performed on the patient and her son, and a splice mutation of the SMARCB1 gene located at C. 1118+1G>A on intron 8 was identified.

Conclusions

Schwannomatosis is an incomplete dominant autosomal dominant genetic disorder. The structural and functional abnormalities of proteins caused by mutations in the SMARCB1 gene may be the molecular basis for familial schwannomatosis.

Neurofibromatosis: New Clinical Challenges in the Era of COVID-19

Rare diseases constitute a wide range of disorders thus defined for their low prevalence. However, taken together, rare diseases impact a considerable percentage of the world population, thus representing a public healthcare problem. In particular, neurofibromatoses are autosomal-dominant genetic disorders that include type 1 neurofibromatosis (NF1), type 2 neurofibromatosis (NF2) and schwannomatosis. Each of the three types is a genetically distinct disease with an unpredictable clinical course and for which there is still no resolutive cure. Therefore, a personalized therapeutic approach directed at improving the symptomatology as well as the search for new pharmacological strategies for the management of neurofibromatosis represents a priority for positive outcomes for affected patients. The coronavirus disease 2019 (COVID-19) pandemic has severely affected health systems around the world, impacting the provision of medical care and modifying clinical surveillance along with scientific research procedures. COVID-19 significantly worsened exchanges between healthcare personnel and neurofibromatosis patients, precluding continuous clinical monitoring in specialized clinic centers. In this new scenario, our article presents, for the first time, a comprehensive literature review on the clinical challenges for neurofibromatosis clinical care and research during the COVID-19 pandemic health emergency. The review was performed through PubMed (Medline) and Google Scholar databases until December 2021.

Comparison of the frequency of loss-of-function LZTR1 variants between Schwannomatosis patients and the general population

Schwannomatosis is a rare tumour predisposition syndrome that causes multiple schwannomas. Germline loss-of-function LZTR1 variants were only recently identified as disease-causing, so relatively few variants have been identified in patients. In addition, many loss-of-function variants exist in gnomAD in people who do not have clinical symptoms of schwannomatosis. These factors, and the incomplete penetrance seen in this condition, hinder definitive interpretation of the clinical significance of novel loss-of-function variants identified in schwannomatosis patients. We collated published loss-of-function LZTR1 variants identified in schwannomatosis patients and classified them according to current ACMG/AMP/ACGS guidelines. Subsequently, pathogenic/likely pathogenic schwannomatosis-associated loss-of-function variants were compared with loss-of-function LZTR1 variants reported in gnomAD data. This article is protected by copyright. All rights reserved.

Prevalence and natural history of schwannomas in neurofibromatosis type 2 (NF2): the influence of pathogenic variants

This study explores the natural history of vestibular, trigeminal and lower cranial nerve schwannomas (VS, TS, LCNS) in patients with Neurofibromatosis type 2 (NF2), to understand how pathogenic variants (PVs) of the NF2 gene affect tumour burden and growth rate, via a retrospective analysis of a UK NF2 centre database and imaging. VS, TS and LCNS location and size were measured in accordance with a standardised protocol. PVs were categorised in accordance with the UK NF2 Genetic Severity Score (GSS). 153 patients (age 5-82) had 458 schwannomas, of which 362 were previously untreated comprising: 204 VS, 93 TS, and 65 LCNS (IX, X, XI). 322 schwannomas had sequential imaging allowing growth rate analysis with a mean follow-up of 45 months. VS were universally present, and bilateral in 146/153 cases. 65% of tumours grew >2 mm during the study period at mean rate 2.0 mm/year. Significant association was found between increasing GSS and growth rate. TS occurred in 66/153 patients (bilateral in 27/153); 31% of tumours showed growth (mean 1.8 mm/yr). Significant increase in tumour prevalence was noted with increasing GSS. LCNS were found in 47/153 patients (bilateral in 19/153); 27% of tumours showed growth (mean 1.9 mm/yr). The trend for increased prevalence with increasing GSS did not reach significance. VS growth rate was significantly influenced by GSS and they were much more likely to grow than TS and LCNS. TS prevalence also correlated with increasing GSS.

Re-evaluation of Missense Variant Classifications in NF2

Missense variants in the NF2 gene result in variable NF2 disease presentation. Clinical classification of missense variants often represents a challenge, due to lack of evidence for pathogenicity and function. This study provides a summary of NF2 missense variants, with variant classifications based on currently available evidence. NF2 missense variants were collated from pathology‐associated databases and existing literature. Association for Clinical Genomic Sciences Best Practice Guidelines (2020) were followed in the application of evidence for variant interpretation and classification. The majority of NF2 missense variants remain classified as variants of uncertain significance. However, NF2 missense variants identified in gnomAD occurred at a consistent rate across the gene, while variants compiled from pathology‐associated databases displayed differing rates of variation by exon of NF2. The highest rate of NF2 disease‐associated variants was observed in exon 7, while lower rates were observed toward the C‐terminus of the NF2 protein, merlin. Further phenotypic information associated with variants, alongside variant‐specific functional analysis, is necessary for more definitive variant interpretation. Our data identified differences in frequency of NF2 missense variants by exon between gnomAD population data and NF2 disease‐associated variants, suggesting a potential genotype‐phenotype correlation; further work is necessary to substantiate this.

Skull Base Tumors: Neuropathology and Clinical Implications

Tumors that arise in and around the skull base comprise a wide range of common and rare entities. Recent studies have advanced our understanding of their pathogenesis, which in some cases, have significantly influenced clinical practice. The genotype of meningiomas is strongly associated with their phenotype, including histologic subtype and tumor location, and clinical outcome. A single molecular alteration, NAB2-STAT6 fusion, has redefined the category of solitary fibrous tumors to include the previous entity hemangiopericytomas. Schwannomas, both sporadic and familial, are characterized by near ubiquitous alterations in NF2 , with additional mutations in SMARCB1 or LZTR1 in schwannomatosis. In pituitary adenohypophyseal tumors, cell lineage transcription factors such as SF-1, T-PIT, and PIT-1 are now essential for classification, providing a more rigorous taxonomy for tumors that were previously considered null cell adenomas. The pituicyte lineage transcription factor TTF-1 defines neurohypophyseal tumors, which may represent a single nosological entity with a spectrum of morphologic manifestations (ie, granular cell tumor, pituicytoma, and spindle cell oncocytoma). Likewise, the notochord cell lineage transcription factor brachyury defines chordoma, discriminating them from chondrosarcomas. The identification of nonoverlapping genetic drivers of adamantinomatous craniopharyngiomas and papillary craniopharyngiomas indicates that these are distinct tumor entities and has led to successful targeted treatment of papillary craniopharyngiomas using BRAF and/or mitogen-activated protein kinase inhibitors. Similarly, dramatic therapeutic responses have been achieved in patients with Langerhans cell histiocytosis, both with BRAF -mutant and BRAF -wildtype tumors. Familiarity with the pathology of skull base tumors, their natural history, and molecular features is essential for optimizing patient care.

The Genetics and Diagnosis of Pediatric Neurocutaneous Disorders: Neurofibromatosis and Tuberous Sclerosis Complex

Neurofibromatosis (NF) and tuberous sclerosis complex (TSC) are the two most common neurocutaneous disorders, both transmitted as autosomal dominant or, in the case of NF, also as a mosaic condition. The causative genetic mutations in these neurocutaneous disorders can lead to benign skin changes or uninhibited growth and proliferation in multiple organ systems due to the loss of tumor suppression in mitogen-activated protein kinase and mammalian target of rapamycin signaling pathways. Common clinical features in NF include pigmented lesions, known as café au lait patches, neurofibromas, intertriginous freckles (Crowe's sign), and benign fibrous growths, such as hamartomas in multiple organ systems. Common clinical features in TSC include hypopigmented macules, known as ash leaf spots, in addition to neurologic sequelae, such as autism, seizures, and developmental delays. Advances in genetic sequencing technologies have allowed an exponential expansion in the understanding of NF and TSC. Consensus criteria have been established for both diagnoses that can be confirmed in most cases through gene testing. Once diagnosed, the clinical and diagnostic value of disease-specific surveillance include early identification of benign and malignant tumors. Genetic counseling is important for informed reproductive decision-making for patients and at-risk family members. The improvement in understanding of pathways of pathogenic disease development and oncogenesis in both conditions have produced a new series of therapeutic options that can be used to control seizures and tumor growth. Tremendous advances in life expectancy and quality of life are now a reality due to early introduction of seizure control and novel medications. While we lack cures, early institution of interventions, such as seizure control in tuberous sclerosis, appears to be disease-modifying and holds immense promise to offer patients better lives.

Integrative molecular and clinical profiling of acral melanoma links focal amplification of 22q11.21 to metastasis

Acral melanoma, the most common melanoma subtype among non-White individuals, is associated with poor prognosis. However, its key molecular drivers remain obscure. Here, we perform integrative genomic and clinical profiling of acral melanomas from 104 patients treated in North America (n = 37) or China (n = 67). We find that recurrent, late-arising focal amplifications of cytoband 22q11.21 are a leading determinant of inferior survival, strongly associated with metastasis, and linked to downregulation of immunomodulatory genes associated with response to immune checkpoint blockade. Unexpectedly, LZTR1 - a known tumor suppressor in other cancers - is a key candidate oncogene in this cytoband. Silencing of LZTR1 in melanoma cell lines causes apoptotic cell death independent of major hotspot mutations or melanoma subtypes. Conversely, overexpression of LZTR1 in normal human melanocytes initiates processes associated with metastasis, including anchorage-independent growth, formation of spheroids, and an increase in MAPK and SRC activities. Our results provide insights into the etiology of acral melanoma and implicate LZTR1 as a key tumor promoter and therapeutic target.

Identification of key biomarkers and immune infiltration in sporadic vestibular schwannoma basing transcriptome-wide profiling

BACKGROUND

Vestibular schwannoma (VS) is a common intracranial tumor, with 95% of the cases being sporadic vestibular schwannoma (SVS). The purposed of this study was identifying genes responsible for inflammation in SVS and clarifying its underlying immune mechanisms.

METHODS

Transcriptional sequencing datasets (GSE141801 and GSE108237) from the Gene Expression Omnibus (GEO) database were used in this study. The candidate modules closely related to SVS and hub genes were screened out by weighted gene co-expression network analysis. Τhe sensitivity and specificity of the hub genes for SVS prediction were evaluated by ROC curve analysis. The CIBERSORT algorithm was subsequently applied to analyze the immune infiltration between SVS and controls. Finally, biological signaling pathways involved in the hub genes were identified via gene set enrichment analysis.

RESULTS

A total of 39 significantly enriched in myelination and collagen-containing extracellular matrix DEGs were identified at the screening step. Three hub genes (MAPK8IP1, SLC36A2, and OR2AT4) were identified, which mainly enriched in pathways of melanogenesis, GnRH, and calcium signaling pathways. Compared with normal nerves, SVS tissue contained a higher proportion of T cells, monocytes and activated dendritic cells, whereas proportions of M2 macrophages were lower.

CONCLUSIONS

The intergrated analysis revealed the pattern of immune cell infiltration in SVS and provided a crucial molecular foundation to enhance understanding of SVS. Hub genes MAPK8IP1, SLC36A2 and OR2AT4 are potential biomarkers and therapeutic targets to facilitate the accurate diagnosis, prognosis and therapy of SVS.

Clinical Trials Targeting Neurofibromatoses-associated Tumors: A Systematic Review

Background

There is a paucity of literature that comprehensively analyzes previous and current clinical trials targeting neurofibromatoses-related tumors. This article aims to provide readers with drug development efforts targeting these tumors by analyzing translational and clinical findings.

Methods

This systematic review was written according to the PRISMA guidelines. Inclusion criteria were clinical trials involving patients with neurofibromatosis type 1, type 2, or schwannomatosis that were treated with therapies targeting neurofibromatoses-associated tumors and that were registered on clinicaltrials.gov. In addition, a search was performed in PubMed, Web of Science, Google Scholar, and Embase European for articles fully describing these clinical trials.

Results

A total of 265 clinical trials were registered and screened for eligibility. Ninety-two were included in this systematic review involving approximately 4636 participants. The number of therapies analyzed was more than 50. Drugs under investigation mainly act on the MAPK/ERK and PI3K/AKT/mTOR pathways, tumor microenvironment, or aberrantly over-expressed cell surface receptors. Selumetinib was the most effective medication for treating a neurofibromatosis type 1-associated tumor with approximately 68%–71% partial response for inoperable or progressive plexiform neurofibromas in children 2 years of age and older and bevacizumab for a neurofibromatosis type 2-related tumor with approximately 36%–41% partial response for vestibular schwannomas in patients 12 years of age and older.

Conclusions

This systematic review presents the results of previous clinical investigations and those under development for neurofibromatoses-associated tumors. Clinicians may use this information to strategize patients to appropriate clinical trials.

Neurofibromatosis in Children: Actually and Perspectives

The three types of neurofibromatosis, namely type 1, type 2, and schwannomatosis, are generally associated with various benign tumors affecting the skin and the nervous system. On rare occasions, especially in patients with neurofibromatosis type 1 (NF1), malignant neoplasms may also be present, several of them possessing a more aggressive course than in individuals without this syndrome. As such, a clear delineation between the three variants of neurofibromatosis is crucial to establish the correct diagnosis and management, as well as predict the neoplasm-related outcomes. Neurofibromin, the principal product of the NF1 gene, is a potent inhibitor of cellular proliferation, having been linked to several key signaling pathways involved in tumor growth. Therefore, it may provide a useful therapeutic target for tumor management in these patients. In this article, we want to present the association between deficiency of neurofibromin and the consequences of the lack of this protein leading to different kinds of malignant tumors. The therapy is still uncertain and most therapeutic options are in development or clinical trials.

Targeted massively parallel sequencing of candidate regions on chromosome 22q predisposing to multiple schwannomas: An analysis of 51 individuals in a single-center experience

Constitutional LZTR1 or SMARCB1 pathogenic variants (PVs) have been found in ∼86% of familial and ∼40% of sporadic schwannomatosis cases. Hence, we performed massively parallel sequencing of the entire LZTR1, SMARCB1, and NF2 genomic loci in 35 individuals with schwannomas negative for constitutional first-hit PVs in the LZTR1/SMARCB1/NF2 coding sequences; however, with 22q deletion and/or a different NF2 PV in each tumor, including six cases with only one tumor available. Furthermore, we verified whether any other LZTR1/SMARCB1/NF2 (likely) PVs could be found in 16 cases carrying a SMARCB1 constitutional variant in the 3'-untranslated region (3'-UTR) c.*17C>T, c.*70C>T, or c.*82C>T. As no additional variants were found, functional studies were performed to clarify the effect of these 3'-UTR variants on the transcript. The 3'-UTR variants c.*17C>T and c.*82C>T showed pathogenicity by negatively affecting the SMARCB1 transcript level. Two novel deep intronic SMARCB1 variants, c.500+883T>G and c.500+887G>A, resulting in out-of-frame missplicing of intron 4, were identified in two unrelated individuals. Further resequencing of the entire repeat-masked genomics sequences of chromosome 22q in individuals negative for PVs in the SMARCB1/LZTR1/NF2 coding- and noncoding regions revealed five potential schwannomatosis-predisposing candidate genes, that is, MYO18B, NEFH, SGSM1, SGSM3, and SBF1, pending further verification.

Structural Abnormalities of the Central Retina in Neurofibromatosis Type 2

INTRODUCTION

This case-control study seeks to systematically characterize the central retinal findings in a large cohort of patients with neurofibromatosis type 2 (NF2) using spectral domain optical coherence tomography (SD-OCT) as well as the examination of the potential use of this technique as a diagnostic tool in NF2.

METHODS

Fifty-four patients with an NF2 diagnosis seen in a quaternary national service were age- and gender-matched to 55 controls from the normal population. Two masked assessors categorized SD-OCT images using predefined abnormalities: retinal tufts, epiretinal membrane (ERM) appearance, retinal hamartoma, and foveal contour. Specificity, sensitivity, and positive and negative predictive values were calculated for each retinal abnormality. Trends of retinal abnormalities with NF2 genetic severity groups (1. tissue mosaic; 2A. mild classic; 2B. moderate classic; and 3. severe) were investigated.

RESULTS

We found retinal abnormalities in 26 patients with NF2 (48%) and 2 control patients (4%); retinal tufts were the most common abnormality therein (43%) and were not seen in controls. The specificity and sensitivity of the graded abnormalities on OCT scans in NF2 were 96% and 48%, respectively, with a positive predictive value of 93%. In our cohort, retinal tufts had a specificity of 100%, a sensitivity of 43%, and a positive predictive value of 100%. Retinal hamartomas were seen only in NF2 patients (35% sensitivity and 100% specificity). ERMs had 96% specificity and 13% sensitivity. The proportion of patients with retinal abnormalities increased statistically significantly with NF2 genetic severity; all patients within the 3. severe genetic severity had an abnormal SD-OCT.

DISCUSSION/CONCLUSION

We present a systematic study of central retinal abnormalities in an NF2 population as seen on SD-OCT imaging. Our results show a high frequency of retinal abnormalities that are readily detected by SD-OCT imaging. The presence of retinal tufts may be a novel marker of NF2 with both high specificity and a positive predictive value for NF2, compared to other well-known ocular features of NF2, and may have a place in the NF2 diagnostic criteria.

Neurofibromatoses

The neurofibromatoses are a group of genetic disorders that cause development of nervous system tumors as well as various other tumor and systemic manifestations. Neurofibromatosis type 1 is the most prevalent of these conditions and has the most variable phenotype and highest risk of malignant tumor formation. Neurofibromatosis type 2 has no associated malignant tumors but does carry significant morbidity, including deafness, facial weakness, and physical disability. Schwannomatosis is the least prevalent of these disorders and is characterized primarily by nonvestibular schwannomas and pain.

Reliability and toxicity of bevacizumab for neurofibromatosis type 2-related vestibular schwannomas: A systematic review and meta-analysis

BACKGROUND

The anti-angiogenic agent bevacizumab is currently the only drug used clinically for neurofibromatosis type 2-related vestibular schwannomas (NF2-VS). Though benefits have been demonstrated in several cases, the standardized dosage remains unclear.

OBJECTIVE

Our meta-analysis was performed to systematically and comprehensively investigate the reliability and toxicity of bevacizumab in the treatment of NF2-VS, with particular emphasis on the impact of dosage.

METHODS

The literature search was conducted for studies providing data on patients treated with bevacizumab for NF2-VS across PubMed, Embase, and Cochrane Library until December 31, 2020. Two reviewers extracted the incidence rate of results independently. Then we calculated and pooled unadjusted incidence rate with 95% CIs for each study. The subgroups analyzed were conducted.

RESULTS

Fourteen citations (prospective or retrospective observational cohort studies) were eligible based on data from a total of 247 patients with NF2 and 332 related VSs. The pooled results showed that the radiographic response rate (RRR) was 30% [95% CI (20%-42%)], the hearing response rate (HRR) was 32% [95% CI (21%-45%)]. The incidence of major complications was: hypertension 29% [95% CI (23%-35%)], proteinuria 30% [95% CI (18%-44%)], menstrual disorders 44% [95% CI (16%-73%)], hemorrhage 14% [95% CI (4%-26%)], grade3/4 events 12% [95% CI (4%-22%)].

CONCLUSIONS

Nearly one-third of NF2-VS patients may benefit significantly from bevacizumab due to hearing improvement and tumor reduction. Menstrual disorders were the most common adverse events. The high-dose regimen didn't show better efficacy, but results varied considerably according to age.

Revisiting the UK Genetic Severity Score for NF2: a proposal for the addition of a functional genetic component

BACKGROUND

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterised by the development of multiple schwannomas, especially on vestibular nerves, and meningiomas. The UK NF2 Genetic Severity Score (GSS) is useful to predict the progression of the disease from germline NF2 pathogenic variants, which allows the clinical follow-up and the genetic counselling offered to affected families to be optimised.

METHODS

52 Spanish patients were classified using the GSS, and patients' clinical severity was measured and compared between GSS groups. The GSS was reviewed with the addition of phenotype quantification, genetic variant classification and functional assays of Merlin and its downstream pathways. Principal component analysis and regression models were used to evaluate the differences between severity and the effect of NF2 germline variants.

RESULTS

The GSS was validated in the Spanish NF2 cohort. However, for 25% of mosaic patients and patients harbouring variants associated with mild and moderate phenotypes, it did not perform as well for predicting clinical outcomes as it did for pathogenic variants associated with severe phenotypes. We studied the possibility of modifying the mutation classification in the GSS by adding the impact of pathogenic variants on the function of Merlin in 27 cases. This revision helped to reduce variability within NF2 mutation classes and moderately enhanced the correlation between patient phenotype and the different prognosis parameters analysed (R²=0.38 vs R²=0.32, p>0001).

CONCLUSIONS

We validated the UK NF2 GSS in a Spanish NF2 cohort, despite the significant phenotypic variability identified within it. The revision of the GSS, named Functional Genetic Severity Score, could add value for the classification of mosaic patients and patients showing mild and moderate phenotypes once it has been validated in other cohorts.