Past, Present, and Future Therapeutic Strategies for NF-1-Associated Tumors

PURPOSE OF REVIEW

Neurofibromatosis type 1 (NF-1) is a cancer predisposition syndrome caused by mutations in the NF1 tumor suppressor gene that encodes the neurofibromin protein, which functions as a negative regulator of Ras signaling. We review the past, current, and future state of therapeutic strategies for tumors associated with NF-1.

RECENT FINDINGS

Therapeutic efforts for NF-1-associated tumors have centered around inhibiting Ras output, leading to the clinical success of downstream MEK inhibition for plexiform neurofibromas and low-grade gliomas. However, MEK inhibition and similar molecular monotherapy approaches that block Ras signaling do not work for all patients and show limited efficacy for more aggressive cancers such as malignant peripheral nerve sheath tumors and high-grade gliomas, motivating novel treatment approaches. We highlight the current therapeutic landscape for NF-1-associated tumors, broadly categorizing treatment into past strategies for serial Ras pathway blockade, current approaches targeting parallel oncogenic and tumor suppressor pathways, and future avenues of investigation leveraging biologic and technical innovations in immunotherapy, pharmacology, and gene delivery.

Low-grade glioma in children with neurofibromatosis type 1: surveillance, treatment indications, management, and future directions

Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome characterized by the development of both central and peripheral nervous system tumors. Low-grade glioma (LGG) is the most prevalent central nervous system tumor occurring in children with NF1, arising most frequently within the optic pathway, followed by the brainstem. Historically, treatment of NF1-LGG has been limited to conventional cytotoxic chemotherapy and surgery. Despite treatment with chemotherapy, a subset of children with NF1-LGG fail initial therapy, have a continued decline in function, or recur. The recent development of several preclinical models has allowed for the identification of novel, molecularly targeted therapies. At present, exploration of these novel precision-based therapies is ongoing in the preclinical setting and through larger, collaborative clinical trials. Herein, we review the approach to surveillance and management of NF1-LGG in children and discuss upcoming novel therapies and treatment protocols.

Impact of trametinib on the neuropsychological profile of NF1 patients

PURPOSE

The use of trametinib in the treatment of pediatric low-grade gliomas (PLGG) and plexiform neurofibroma (PN) is being investigated in an ongoing multicenter phase II trial (NCT03363217). Preliminary data shows potential benefits with significant response in the majority of PLGG and PN and an overall good tolerance. Moreover, possible benefits of MEK inhibitor therapy on cognitive functioning in neurofibromatosis type 1 (NF1) were recently shown which supports the need for further evaluation.

METHODS

Thirty-six patients with NF1 (age range 3-19 years) enrolled in the phase II study of trametinib underwent a neurocognitive assessment at inclusion and at completion of the 72-week treatment. Age-appropriate Wechsler Intelligence Scales and the Trail Making Test (for children over 8 years old) were administered at each assessment. Paired t-tests and Reliable Change Index (RCI) analyses were performed to investigate change in neurocognitive outcomes. Regression analyses were used to investigate the contribution of age and baseline score in the prediction of change.

RESULTS

Stable performance on neurocognitive tests was revealed at a group-level using paired t-tests. Clinically significant improvements were however found on specific indexes of the Wechsler intelligence scales and Trail Making Test, using RCI analyses. No significant impact of age on cognitive change was evidenced. However, lower initial cognitive performance was associated with increased odds of presenting clinically significant improvements on neurocognitive outcomes.

CONCLUSION

These preliminary results show a potential positive effect of trametinib on cognition in patients with NF1. We observed significant improvements in processing speed, visuo-motor and verbal abilities. This study demonstrates the importance of including neuropsychological evaluations into clinical trial when using MEK inhibitors for patients with NF1.

Social cognition in children with neurofibromatosis type 1

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a genetic pathology that can lead to impaired social functioning that has a negative impact on patients' quality of life. To date, although the hypothesis of impaired social cognition has been proposed as a potential explanation for these difficulties, very few studies have focused on theory of mind in children with NF1. Furthermore, other complex sociocognitive abilities have never been investigated. The aim of the present study was to assess theory of mind, moral reasoning, and social information processing in children with NF1 compared with a control group.

METHOD

We administered the Paediatric Evaluation of Emotions, Relationships and Socialization® to 38 children with NF1 aged between 8 years and 16 years 11 months (mean = 11.4, SD = 2.3) and 43 control children with comparable sociodemographic characteristics.

RESULTS

Patients performed significantly worse than controls on moral reasoning and social information processing tests, but there was no significant difference on theory of mind.

CONCLUSIONS

These results seem to confirm the presence of social cognition difficulties in NF1 that could explain, at least in part, their social difficulties, although not all dimensions are concerned. The differences between the processes we assessed are discussed in relation to the methodologies used to measure them, and raises questions about the complementarity of traditional tools and more ecological assessments.

Identifying Lesions of the Corpus Callosum in Patients With Neurofibromatosis Type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystemic autosomal dominant disorder that includes intracranial lesions such as unidentified bright objects (UBOs)-areas of increased T2 signal on magnetic resonance imaging (MRI)-and tumors known as gliomas. The presence of these lesions in the corpus callosum (CC) has not been previously studied in a large cohort.

METHODS

We reviewed medical records of 681 patients (aged three months to 86 years) followed at our institution from 2000 to 2023 with NF1 and one or more brain MRI. Patients with lesions in the CC were identified, and RAPNO/RANO criteria were used to determine changes in size over time, where a change of 25% in the product of perpendicular measurements indicates growth or shrinkage.

RESULTS

Forty-seven patients had CC UBOs, most of which were in the splenium (66.0%). Seventeen patients had CC gliomas (10% of those with any glioma), two of whom had two gliomas. Seventeen of 19 gliomas were in the splenium. Over follow-up, eight of 19 remained stable, three shrunk, and eight grew. The mean percentage change in the product of the dimensions was 311.5% (ranging from -46.7% to 2566.6%). Of the eight lesions that grew, one required treatment.

CONCLUSIONS

There is a 6.9% and 2.5% prevalence of CC UBOs and gliomas, respectively, in our cohort of patients with NF1. Most lesions are present in the splenium, and although some gliomas demonstrate significant growth, they rarely require treatment. This work is the largest series of CC lesions in NF1 and adds to the growing data to inform appropriate follow-up.

RASopathies influences on neuroanatomical variation in children

BACKGROUND

RASopathies are a group of disorders characterized by pathogenic mutations in the Ras-mitogen-activated protein kinase (Ras/MAPK) signaling pathway. Distinct pathogenic variants in genes encoding proteins in the Ras/MAPK pathway cause Noonan syndrome (NS) and neurofibromatosis type 1 (NF1), which are associated with increased risk for autism spectrum disorder (ASD) and attention deficit and hyperactivity disorder (ADHD).

METHODS

This study examines the effect RASopathies (NS and NF1) has on human neuroanatomy, specifically on surface area (SA), cortical thickness (CT), and subcortical volumes. We compared structural T1-weighted images, using vertex-based analysis for cortical measures and Desikan ROI parcellation for subcortical volumes on children with RASopathies (n=91, mean age = 8.81, SD = 2.12) to sex- and age-matched TD (n=74, mean age=9.07, SD = 1.77).

RESULTS

Compared to TD, RASopathies had convergent effects on SA and CT, exhibiting increased SA in the precentral gyrus, decreased SA in occipital regions, and thinner CT in the precentral gyrus. RASopathies exhibit divergent effects on subcortical volumes, with syndrome-specific influences from NS and NF1. Overall children with NS display decreased volumes in striatal and thalamic structures and children with NF1 display increased volumes in the hippocampus, amygdala, and thalamus.

CONCLUSIONS

Our study reveals the converging and diverging neuroanatomical effects of RASopathies on human neurodevelopment. The convergence of cortical effects on SA and CT indicates a shared influence of Ras/MAPK hyperactivation on the human brain. Therefore, considering these measures as objective outcome indicators for targeted treatments is imperative.

Genotype-phenotype correlations of neurofibromatosis type 1: a cross-sectional study from a large Chinese cohort

BACKGROUND

Neurofibromatosis type 1 (NF1) is a highly heterogeneous autosomal genetic disorder characterized by a broad spectrum of clinical and molecular manifestations. The correlations between genotype and phenotype in NF1 remain elusive. This study aimed to elucidate genotype-phenotype associations in a large Chinese cohort of NF1 patients.

METHODS

We included NF1 patients from our center who underwent genetic testing for NF1 variants and systemic examination. Genotype-phenotype correlation analyses were performed, focusing on variation types and involved neurofibromin domains.

RESULTS

A total of 195 patients were enrolled, comprising 105 males and 90 females, with a median age of 18 years. Truncating variants, single amino acid variations, and splicing variants accounted for 139/195 (71.3%), 23/195 (11.8%), and 33/195 (16.9%), respectively. Patients with splicing variants exhibited a significantly higher prevalence of spinal plexiform neurofibromas (spinal PNF) than those with truncating variants (76.4% vs. 51.8%; p = 0.022). Variations affecting the PKC domain were associated with higher rates of cutaneous neurofibromas (CNF) (100% vs. 64.9%, p < 0.001), Lisch nodules (100% vs. 61.2%, p < 0.001), plexiform neurofibromas (PNF) (100% vs. 95.7%, p = 0.009), and psychiatric disorders (11.8% vs. 1.6%, p = 0.042). Patients with mutations in the CSRD had an elevated risk of secondary primary malignancies (11.6% vs. 2.8%, p = 0.015). GRD involvement might enhance the risk of Lisch nodules (76.9% vs. 53.7%, p = 0.044). Variations in the Sec14-PH domain were correlated with a higher rate of CNF (76.8% vs. 58.6%, p = 0.014). Additionally, we found that the p.R1748* variants carry a high risk of malignancy.

CONCLUSION

Our study suggested some novel genotype-phenotype correlations within a Chinese cohort, providing innovative insights into this complex field that may contribute to genetic counseling, risk stratification, and clinical management for the NF1 population.

A novel stop-gain NF1 variant in neurofibromatosis type 1 and bilateral optic atrophy without optic gliomas

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystem disorder that primarily affects the skin and peripheral nervous system and is caused by chromosomal abnormalities and mostly truncating variants in the NF1 gene. Ocular complications such as Lisch nodules and optic pathway gliomas (OPGs) can occur in NF1 patients. Herein, we report a novel NF1 variant in an NF1 patient with bilateral optic atrophy.

METHODS

Ophthalmological examinations and genetic analyses were performed using targeted next-generation sequencing (NGS).

RESULTS

A 14-year-old girl diagnosed with NF1 visited our hospital with decreased visual acuity (VA). The patient had no family history of NF1 or visual impairment. Brain and orbital magnetic resonance imaging revealed no remarkable findings. Ophthalmoscopy revealed temporal pallor of the optic discs, which was confirmed by optical coherence tomography findings of significant thinning of the circumpapillary retinal nerve fiber layer in both eyes. At 23 years of age, the decimal-corrected VA had deteriorated to 0.2 in the right eye and 0.1 in the left eye. Additionally, the targeted NGS panel revealed a novel heterozygous stop-gain variant (p.Tyr628Ter) in the NF1 gene; however, no pathogenic variants in OPA1 or the mitochondrial DNA were identified.

CONCLUSIONS

A patient with NF1 without OPGs developed bilateral optic atrophy and carried a novel de novo stop-gain variant of NF1. Although the relationship between NF1 variants and bilateral optic atrophy remains unclear, further investigations are required.

Uncommon Thigh Mass in Neurofibromatosis Type 1: Unveiling Aggressive Epithelioid Sarcoma

Background

Patients with neurofibromatosis type I (NF1) have an increased risk of developing soft-tissue sarcomas, particularly those related to the nervous system. Epithelioid sarcoma (ES) is an exceptionally rare subtype of soft-tissue sarcoma, with limited knowledge about its clinical presentation and optimal management in NF1. This report aims to provide insights into the characteristics and outcomes of ES in NF1 patients.

Case description

A 37-year-old man with a history of NF1 presented with a progressively worsening mass on his right inner thigh. An MRI scan revealed a well-defined tissue mass originating from the adductor magnus muscle, later confirmed as ES through histopathology and immunohistochemistry. Considering poor local and general prognosis, the multidisciplinary team recommended salvage hip disarticulation, however the patient refused and opted for palliative marginal resection to reduce the tumour size. The patient's condition declined rapidly, and he succumbed six days after the surgery.

Conclusion

This case highlights the rarity of ES in NF1 patients and underscores the potential for malignant tumour development in this population. Further research is needed to improve our understanding and management of sarcomas in the context of NF1.

LEARNING POINTS

Patients with neurofibromatosis type 1 or von Recklinghausen's disease have a higher risk than those with other types of neurofibromatosis of developing benign or malignant soft-tissue tumours especially related to the nervous system.Epithelioid sarcoma is an extremely rare subtype of soft-tissue sarcoma and is exceptionally associated with neurofibromatosis type 1.A multidisciplinary approach remains essential in the diagnosis, management, and treatment of soft-tissue sarcomas in patients with neurofibromatosis type 1.

Clinical features and surgical treatments of scoliosis in neurofibromatosis type 1: a systemic review and meta-analysis

BACKGROUND

Neurofibromatosis type 1 (NF 1) is an autosomal-dominant tumor predisposition genetic disease affecting approximately 1 in 3000 live births. The condition could present various manifestations ranging from skin abnormalities to neurological tumors. The musculoskeletal system could also be frequently affected, and scoliosis is the most common orthopedic manifestation. Characterized by the early-onset and rapid progression tendency, NF 1-related dystrophic scoliosis presented discrepancies from idiopathic scoliosis in terms of natural history, clinical features, and management outcomes and thus required special attention. In the current study, the authors conducted a systemic review to outline the body of evidence of the natural history, clinical characteristics, surgical outcomes, and surgical complications of NF 1-induced scoliosis, aiming to provide an elucidative insight into this condition.

METHOD

Systemic review and meta-analysis were conducted according to the latest Preferred Reporting Items for Systematic Reviews Meta-Analyses (PRISMA) guidelines. The search was performed in Medline, Embase, and Web of Science Core Collection up to December 27, 2022, using related keywords. Clinical features such as frequencies, segmental involvement, and hereditary information were summarized and described qualitatively. Meta-analysis was conducted using R software and the 'meta' package to yield an overall outcome of efficacy and safety of surgical management, precisely, spinal fusion procedure and growing rods procedure. Corrective rate of Cobb angle, sagittal kyphosis angle, and T1-S1 length post-operative and at the last follow-up was used to evaluate the efficacy, and the occurrence of surgery-related complications was used to evaluate the safety.

RESULT

A total of 37 articles involving 1023 patients were included. Approximately 26.6% of the NF 1 patients would present with scoliosis. Patients tend to develop scoliosis at an earlier age. The thoracic part turned out to be the most affected segment. No obvious correlation between scoliosis and genotype or hereditary type was observed. Both spinal fusion and growing rod surgery have shown acceptable treatment outcomes, with spinal fusion demonstrating better performance in terms of effectiveness and safety. The growing rods technique seemed to allow a better lengthening of the spine. The mainstay post-operative complications were implant-related complications but could be managed with limited revision surgery. Severe neurological deficits were rarely reported.

CONCLUSION

Scoliosis, especially the subtype characterized by dystrophic bony changes, is a significant orthopedic manifestation of NF1. It has an early onset, a tendency to persistently and rapidly progress, and is challenging to deal with. The current review outlines the available evidence from the perspective of natural history, clinical features, and the treatment efficacy and safety of the mainstay surgical options. Patients with NF1 scoliosis will benefit from a better understanding of the disease and evidence based treatment strategies.

The PlexiQoL, a patient-reported outcome measure on quality of life in neurofibromatosis type 1-associated plexiform neurofibroma: translation, cultural adaptation and validation into the Dutch language for the Netherlands

BACKGROUND

Half of the patients with Neurofibromatosis type 1 (NF1) develop one or more tumours called plexiform neurofibromas, which can have a significant impact on Quality of Life (QoL). The PlexiQoL questionnaire is a disease-specific QoL measure for adults with NF1-associated plexiform neurofibromas. The aim of this study was to adapt and validate a Dutch version of the PlexiQoL for the Netherlands.

METHODS

The PlexiQoL was translated using the dual-panel methodology, followed by cognitive debriefing interviews to assess face and content validity. The psychometric properties were evaluated by administering the questionnaire on two separate occasions to a sample of adults with NF1 and plexiform neurofibromas. Feasibility was evaluated by the presence of floor/ceiling effects. Reliability was assessed by evaluating Cronbach's alpha coefficient and test-retest reliability, using Spearman's rank correlation coefficients. Mann-Whitney U tests were used to check for known group validity. The Nottingham Health Profile (NHP) questionnaire was used as comparator questionnaire to evaluate convergent validity.

RESULTS

The translation and cognitive debriefing interviews resulted in a Dutch version of the PlexiQoL that reflected the original concept and underlying semantic meanings of the UK English version. Forty participants completed the validation survey. The Dutch PlexiQoL demonstrated excellent internal consistency (Cronbach's α 0.825) and test-retest reliability (Spearman correlation coefficient 0.928). The questionnaire detected differences in PlexiQoL scores between participants based on self-reported general health and disease severity. Convergent validity was confirmed for relevant NHP subsections.

CONCLUSIONS

The Dutch PlexiQoL demonstrated excellent psychometric properties and can be reliably used to measure plexiform neurofibroma-related QoL in adults with NF1 in the Netherlands.

Association of sociodemographic and clinical factors with the quality of life of Brazilian individuals with Neurofibromatosis type 1: a cross-sectional study

BACKGROUND

Neurofibromatosis type 1 (NF1) is a rare genetic disorder with a wide range of clinical manifestations, notably neurocutaneous features, that can lead to emotional and physical consequences.

OBJECTIVES

This study assessed the influence of sociodemographic factors and clinical features of the disease on the quality of life of Brazilian individuals with NF1.

METHODS

This is a descriptive cross-sectional study. Data were collected from 101 individuals with NF1 using the Brazilian version of the Impact of NF1 on Quality of Life Questionnaire (INF1-QoL), a form with information on sociodemographic characteristics, and an NF1 visibility self-evaluation scale. The relationship between variables was evaluated through statistical testing, and the significance level was defined as 0.05.

RESULTS

The study included 101 adults with NF1 aged 18 to 59 years, with a mean age of 35.54 years (±9.63) and a female predominance (n = 84, 83.17%). The mean total INF1-QoL score was 10.62 (±5.63), with a median of 10, minimum value of 0, and maximum of 31 points. Two characteristics of the participants were significantly associated with the quality of life: educational level (p = 0.003) and familial history of NF1 (p = 0.019). There was a statistically significant correlation between the INF1-QoL score and the degree of disease visibility (rho = 0.218; p = 0.028).

STUDY LIMITATIONS

Cross-sectional study, conducted with a convenience sample and using self-reported measures.

CONCLUSIONS

The findings support the significant impact of NF1 on quality of life. The authors recommend multidisciplinary follow-up for patients, with adherence to anticipatory clinical care measures, adequate pain control, psychological assistance, and genetic counseling.

Robotic resection for splenic artery aneurysm associated with neurofibromatosis type 1: a case report

BACKGROUND

Neurofibromatosis type 1 is an autosomal-dominant disease characterized by café-au-lait spots and neurofibromas, as well as various other symptoms in the bones, eyes, and nervous system. Due to its connection with vascular fragility, neurofibromatosis type 1 has been reported to be associated with vascular lesions, such as aneurysms. However, there have been few reports of abdominal visceral aneurysms associated with neurofibromatosis type 1. Furthermore, there have been no reports of robotic treatment of aneurysms associated with neurofibromatosis type 1. In this report, we describe the case of a patient with neurofibromatosis type 1 with a splenic artery aneurysm who was successfully treated with robotic surgery.

CASE PRESENTATION

This report describes a 41-year-old Asian woman with a history of neurofibromatosis type 1 who was referred to our hospital for evaluation of a 28 mm splenic artery aneurysm observed on abdominal ultrasound. The aneurysm was in the splenic hilum, and transcatheter arterial embolization was attempted; however, this was difficult due to the tortuosity of the splenic artery. Thus, we suggested minimally invasive robotic surgery for treatment and resection of the splenic artery aneurysm with preservation of the spleen. The postoperative course was uneventful, and the patient was discharged on the eighth day after surgery. At 1 year of follow-up, the patient was doing well, with no evidence of recurrence.

CONCLUSION

We encountered a rare case of splenic artery aneurysm in a patient with neurofibromatosis type 1 who was successfully treated with robotic surgery. There is no consensus on treatment modalities for neurofibromatosis-related aneurysms, and endovascular treatment is considered safe and effective; however, surgery remains an important treatment modality. Especially in patients with stable hemodynamic status, robotic surgery may be considered as definitive treatment. To our knowledge, this is the first successfully treated case of a splenic artery aneurysm in a patient with neurofibromatosis type 1.

Pilot study of the effectiveness of a telehealth group for improving peer relationships for adolescents with neurofibromatosis type 1

BACKGROUND

Interventions for social difficulties have not been investigated in the neurofibromatosis type 1 (NF1) population despite observations of elevated rates of social difficulties. In this pilot study, the effectiveness of a 14-week telehealth PEERS® intervention with nineteen adolescents with NF1 (Mage=13.79 years, SD = 1.32) with social skills difficulties was examined. Measures of social outcomes were completed at three timepoints (before, immediately after, and at 14-week follow-up).

RESULTS

Caregiver-reported social-emotional skills, social impairment, caregiver-reported number of adolescent get-togethers, and teen social knowledge showed significant improvement following the intervention.

CONCLUSIONS

The PEERS® intervention is promising to support the social and friendship skills of adolescents with NF1 who have social difficulties.

Correlation between large rearrangements and patient phenotypes in NF1 deletion syndrome: an update and review

About 5-10% of neurofibromatosis type 1 (NF1) patients exhibit large genomic germline deletions that remove the NF1 gene and its flanking regions. The most frequent NF1 large deletion is 1.4 Mb, resulting from homologous recombination between two low copy repeats. This "type-1" deletion is associated with a severe clinical phenotype in NF1 patients, with several phenotypic manifestations including learning disability, a much earlier development of cutaneous neurofibromas, an increased tumour risk, and cardiovascular malformations. NF1 adjacent co-deleted genes could act as modifier loci for the specific clinical manifestations observed in deleted NF1 patients. Furthermore, other genetic modifiers (such as CNVs) not located at the NF1 locus could also modulate the phenotype observed in patients with large deletions. In this study, we analysed 22 NF1 deletion patients by genome-wide array-CGH with the aim (1) to correlate deletion length to observed phenotypic features and their severity in NF1 deletion syndrome, and (2) to identify whether the deletion phenotype could also be modulated by copy number variations elsewhere in the genome. We then review the role of co-deleted genes in the 1.4 Mb interval of type-1 deletions, and their possible implication in the main clinical features observed in this high-risk group of NF1 patients.

Breast density in NF1 women: a retrospective study

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition caused by neurofibromin haploinsufficiency due to pathogenic variants in the NF1 gene. Tumor predisposition has long been associated with NF1, and an increased breast cancer (BC) incidence and reduced survival have been reported in recent years for women with NF1. As breast density is another known independent risk factor for BC, this study aims to evaluate the variability of breast density in patients with NF1 compared to the general population. Mammograms from 98 NF1 women affected by NF1, and enrolled onto our monocentric BC screening program, were compared with those from 300 healthy subjects to verify differences in breast density. Mammograms were independently reviewed and scored by a radiologist and using a Computer-Aided Detection (CAD) software. The comparison of breast density between NF1 patients and controls was performed through Chi-squared test and with multivariable ordinal logistic models adjusted for age, body mass index (BMI), number of pregnancies, and menopausal status.breast density was influenced by BMI and menopausal status in both NF1 patients and healthy subjects. No difference in breast density was observed between NF1 patients and the healthy female population, even after considering the potential confounding factors.Although NF1 and a highly fibroglandular breast are known risk factors of BC, in this study, NF1 patients were shown to have comparable breast density to healthy subjects. The presence of pathogenic variants in the NF1 gene does not influence the breast density value.

Neurofibromatosis type 1-associated plexiform neurofibromas of the neck: topography of lesions and surgical treatment data of 69 patients

PURPOSE

Plexiform neurofibromas (PNF) are rare tumors arising from peripheral nerve sheath cells. PNF are a hallmark in patients with neurofibromatosis type 1 (NF1), a tumor predisposition syndrome. PNF often grow invasively and destructively, what may complicate surgical treatment. Data on frequency, location, and surgical procedures of patients with NF1-associated FPNF are scarce. This study provides treatment data of NF1 patients.

METHODS

Localization and treatment data of 69 NF1 patients with neck PNF were analyzed. Frequency of lesions was recorded in coded colors on schematic neck drawings.

RESULTS

The tumors showed no side preference, were located in the entire area under investigation, and did not respect anatomical units/dermatomes. However, the sternocleidomastoid region was particularly frequently affected. The mean number of surgical measures per patient was 1.33. Complications were extensive swelling, hematoma, and bleeding. Histological assessment usually confirmed the clinical assessment of neoplasm. However, histologic differentiation of PNST reveals differences in between tumors that have been unified in clinical assessment as PNF.

CONCLUSION

The color-coded, schematic overview of the frequency distribution of surgical neck interventions in NF1 patients with PNF proved a useful tool to gain assessment of preferred treatment needs. The imaging procedure may be suitable for controlling the external aspect of natural tumor development (growth, effects of aging) in the same way as the documentation of the post-surgical course. Treatment plans for patients with these tumors should consider that repeated interventions may be necessary to achieve a longer-term stable result.

Central giant-cell granuloma in a patient with neurofibromatosis type 1: 7 years of follow-up

Neurofibromatosis type 1 (NF1) is an autosomally dominant tumor suppressor syndrome and multisystem disease. Central giant-cell granulomas (CGCGs) can be seen in patients with NF1. A 21-year-old female was diagnosed with two CGCGs, one in the mandible and then one in the maxilla, in a 7-year period. Increased incidence of CGCGs in NF1 patients was thought to be caused by an underlying susceptibility to developing CGCG-like lesions in qualitatively abnormal bone, such as fibrous dysplasia. However, germline and somatic truncating second-hit mutations in the NF1 gene have been detected in NF1 patients with CGCGs, validating that they are NF1-associated lesions. Oral manifestations in patients with NF1 are very common. Knowledge of these manifestations and the genetic link between NF1 and CGCGs will enhance early detection and enable optimal patient care.

Anesthesia management for thoracoscopic resection of a huge intrathoracic meningocele: a case report

BACKGROUND

Diagnosed intrathoracic meningocele is an uncommon complication of neurofibromatosis type 1. We report an anesthesia management for a rare case undergoing thoracoscopic resection of a huge intrathoracic meningocele.

CASE PRESENTATION

A 51-year-old woman was scheduled for thoracoscopic meningectomy under general anesthesia. We monitored intrathecal pressure during anesthesia to prevent a decrease in intrathecal pressure. During surgery, the intrathecal pressure occasionally increased by around 5 cmH2O immediately after the insertion of the drainage tube and occasionally decreased by up to 10 cmH2O during the careful slow aspiration of the cerebrospinal fluid (CSF). The pressure rapidly recovered after the interruption of the procedures. She was discharged on postoperative day 4 without major complications.

CONCLUSIONS

The CSF pressure was fluctuated by procedures during thoracoscopic resection of a huge meningocele. A CSF pressure monitoring was useful to detect the sudden change of CSF pressure immediately, which can cause intracranial hemorrhage.

Ophthalmologic Findings in Children with Neurofibromatosis Type 1

The purpose of this study was to evaluate the ophthalmologic findings in children with neurofibromatosis type 1 (NF1) and compare these findings in eyes with and without optic pathway gliomas (OPGs). We carried out a retrospective chart review of children with NF1. We recorded demographic characteristics, clinical manifestations of disease, and ophthalmologic findings including visual acuity, intraocular pressure, cup-to-disc ratio, visual field testing, and optical coherence tomography findings. Ophthalmologic findings were examined for the cohort for initial and final appointments. These findings were also compared between eyes with and without OPGs. The study included 119 participants with 238 total eyes. The most common clinical manifestations of NF1 in this cohort were café au lait macules (98%), axillary or inguinal freckling (91%), Lisch nodules (66%), and cutaneous neurofibromas (57%). Thirty-seven participants had imaging that allowed evaluation for choroidal abnormalities, and 28 (76%) had choroidal lesions. Twenty-seven participants (23%) had OPGs, and 44 eyes were affected. On initial assessment, eyes with OPGs had worse visual acuity. On final examination, eyes with OPGs were more likely to have a worse visual acuity and a thinner generalised retinal nerve fibre layer (RNFL) thickness, inferior RNFL thickness, and temporal RNFL thickness. This study provides longitudinal follow-up of children affected by NF1 with and without OPGs. Eyes with OPGs were found to be associated with worse visual acuity and thinner RNFLs overall on final testing.

Neuropsychological factors associated with performance on the rey-osterrieth complex figure test in children with neurofibromatosis type 1

Children with neurofibromatosis type 1 (NF1) are at considerable risk for cognitive difficulties, including visuospatial deficits and executive dysfunction. This study aimed to (1) assess the overall performance of children with NF1 on the Rey-Osterrieth Complex Figure Test (RCFT) compared to unaffected siblings and (2) examine neuropsychological predictors of RCFT performance in children with NF1. A retrospective clinical audit was performed on neuropsychological records from a multidisciplinary NF1 Clinic in Australia. We searched for children that had completed an assessment between 2000 and 2015 which included the RCFT and other neuropsychological outcomes in this study. These included the Wechsler Intelligence Scale for Children, Judgment of Line Orientation (JLO), Tower of London test, Conners ADHD Scales, and the Behavioral Rating Inventory of Executive Function (BRIEF). The study population consisted of 191 children with NF1 aged 6-16 years, and 55 unaffected siblings recruited from a separate study. Results revealed that 62% of children with NF1 performed at or below the first percentile on the RCFT copy, which was significantly worse than their unaffected siblings. Visuospatial skills, parent-rated executive abilities, ADHD symptoms, and intellectual skills all predicted poorer performance on the RCFT copy, however the best fitting multiple regression model only contained the JLO, BRIEF Metacognition Index, and chronological age. The JLO emerged as the strongest predictor of RCFT performance. This study provides evidence that visuospatial deficits are a key driver of reduced RCFT performance in NF1 and that executive skills as well as a younger age are also independent predictors of RCFT performance.

Gene-targeted therapy for neurofibromatosis and schwannomatosis: The path to clinical trials

Numerous successful gene-targeted therapies are arising for the treatment of a variety of rare diseases. At the same time, current treatment options for neurofibromatosis 1 and schwannomatosis are limited and do not directly address loss of gene/protein function. In addition, treatments have mostly focused on symptomatic tumors, but have failed to address multisystem involvement in these conditions. Gene-targeted therapies hold promise to address these limitations. However, despite intense interest over decades, multiple preclinical and clinical issues need to be resolved before they become a reality. The optimal approaches to gene-, mRNA-, or protein restoration and to delivery to the appropriate cell types remain elusive. Preclinical models that recapitulate manifestations of neurofibromatosis 1 and schwannomatosis need to be refined. The development of validated assays for measuring neurofibromin and merlin activity in animal and human tissues will be critical for early-stage trials, as will the selection of appropriate patients, based on their individual genotypes and risk/benefit balance. Once the safety of gene-targeted therapy for symptomatic tumors has been established, the possibility of addressing a wide range of symptoms, including non-tumor manifestations, should be explored. As preclinical efforts are underway, it will be essential to educate both clinicians and those affected by neurofibromatosis 1/schwannomatosis about the risks and benefits of gene-targeted therapy for these conditions.

Potential endpoints for assessment of bone health in persons with neurofibromatosis type 1

Neurofibromatosis type 1 is a genetic syndrome characterized by a wide variety of tumor and non-tumor manifestations. Bone-related issues, such as scoliosis, tibial dysplasia, and low bone mineral density, are a significant source of morbidity for this population with limited treatment options. Some of the challenges to developing such treatments include the lack of consensus regarding the optimal methods to assess bone health in neurofibromatosis type 1 and limited data regarding the natural history of these manifestations. In this review, the Functional Committee of the Response Evaluation in Neurofibromatosis and Schwannomatosis International Collaboration: (1) presents the available techniques for measuring overall bone health and metabolism in persons with neurofibromatosis type 1, (2) reviews data for use of each of these measures in the neurofibromatosis type 1 population, and (3) describes the strengths and limitations for each method as they might be used in clinical trials targeting neurofibromatosis type 1 bone manifestations. The Response Evaluation in Neurofibromatosis and Schwannomatosis International Collaboration supports the development of a prospective, longitudinal natural history study focusing on the bone-related manifestations and relevant biomarkers of neurofibromatosis type 1. In addition, we suggest that the neurofibromatosis type 1 research community consider adding the less burdensome measurements of bone health as exploratory endpoints in ongoing or planned clinical trials for other neurofibromatosis type 1 manifestations to expand knowledge in the field.

Perception and recognition of primary and secondary emotions by children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a genetic disease that can lead to impaired social adaptation and functioning, thus affecting quality of life. To date, studies of these children's social cognition abilities have been scant and far from exhaustive. Therefore, the purpose of the present study was to assess the ability of children with NF1, compared with controls, to process facial expressions of emotions - not only including the usual primary emotions (happiness, anger, surprise, fear, sadness and disgust), but secondary emotions, too. To do so, the links between this ability and the characteristics of the disease (mode of transmission, visibility, and severity) were examined. A total of 38 children with NF1 aged 8-16 years 11 months (mean = 11.4, SD = 2.3) and 43 sociodemographically comparable control children performed the emotion perception and recognition tests of a social cognition battery. Results confirmed that the processing of primary and secondary emotions is impaired in children with NF1, but there were no significant links with either mode of transmission, severity, or visibility. These results encourage further comprehensive assessments of emotions in NF1, and suggest that investigations should be extended to higher level social cognition skills, such as theory of mind and moral judgments.

Perspectives of adolescents with neurofibromatosis 1 and cutaneous neurofibromas: Implications for clinical trials

BACKGROUND/AIMS

More than 99% of individuals with neurofibromatosis 1 develop cutaneous neurofibromas, benign nerve sheath tumors that manifest as nodules on the skin. These cutaneous neurofibromas emerge with age, appearing most commonly in adolescence. Nevertheless, few data have been published on how adolescents with neurofibromatosis 1 feel about cutaneous neurofibromas. The purpose of this study was to assess the perspectives of adolescents with neurofibromatosis 1 and their caregivers regarding cutaneous neurofibroma morbidity, treatment options, and acceptable risks-benefits of treatment.

METHODS

An online survey was distributed through the world's largest NF registry. Eligibility criteria included self-reported neurofibromatosis 1 diagnosis, adolescent child ages 12-17 years, ≥1 cutaneous neurofibroma, and ability to read English. The survey was designed to collect details about the adolescent's cutaneous neurofibromas, views on morbidity related to cutaneous neurofibromas, social and emotional impact of cutaneous neurofibromas, communication regarding cutaneous neurofibromas, and views regarding current and potential future cutaneous neurofibroma treatment.

RESULTS

Survey respondents included 28 adolescents and 32 caregivers. Adolescents reported having several negative feelings about cutaneous neurofibromas, particularly feeling worried about the potential progression of their cutaneous neurofibromas (50%). Pruritus (34%), location (34%), appearance (31%), and number (31%) were the most bothersome cutaneous neurofibroma features. Topical medication (77%-96%), followed by oral medication (54%-93%), was the most preferred treatment modality. Adolescents and caregivers most often replied that cutaneous neurofibroma treatment should be initiated when cutaneous neurofibromas become bothersome. The majority of respondents were willing to treat cutaneous neurofibromas for at least 1 year (64%-75%). Adolescent and caregivers were least willing to risk pain (72%-78%) and nausea/vomiting (59%-81%) as a cutaneous neurofibroma treatment side effect.

CONCLUSIONS

These data indicate that adolescents with neurofibromatosis 1 are negatively impacted by their cutaneous neurofibromas, and that both adolescents and their caregivers would be willing to try longer-term experimental treatments.

Clinical signs and genetic evaluation of patients with neurofibromatosis type 1 with and without optic pathway gliomas in a center in Turkey

PURPOSE

Optic pathway gliomas (OPGs) occur in 15% of patients with neurofibromatosis type 1 (NF1). Their location renders biopsy or surgical resection difficult because of the risk of vision loss. Therefore, only a few NF1-OPGs have been used for tissue diagnosis, and only a few analyses have been published on the molecular changes that drive tumorigenesis.

METHODS

Due to this reason, we evaluated 305 NF1 patients, 34 with OPG and 271 without OPG for germ line mutations. All subjects underwent clinical examination and DNA analysis of NF1, confirming the diagnosis of NF1.

RESULTS

Clinically, the group with OPG had a significantly higher incidence of bone dysplasia (P < 0.001) and more café-au-lait spots (P = 0.001) compared to those in the group without OPG. The frequency of Lisch nodules was on the borderline of statistical significance (P = 0.058), whereas the frequency of neurofibromas did not differ significantly (cutaneous, P = 0.64; plexiform, P = 0.44). Individuals with OPG mostly had mutations in the first one-third of the NF1 gene compared with that in patients who did not have OPG. Some identical mutations were detected in unrelated families with NF1-OPG.

CONCLUSION

The observation of certain phenotypic features and the correlation between genotype and phenotype might help to determine the risk of developing OPG with NF1.

[Gene therapy strategies and prospects for neurofibromatosis type 1]

Objective

To summarize the gene therapy strategies for neurofibromatosis type 1 (NF1) and related research progress.

Methods

The recent literature on gene therapy for NF1 at home and abroad was reviewed. The structure and function of the NF1 gene and its mutations were analyzed, and the current status as well as future prospects of the transgenic therapy and gene editing strategies were summarized.

Results

NF1 is an autosomal dominantly inherited tumor predisposition syndrome caused by mutations in the NF1 tumor suppressor gene, which impair the function of the neurofibromin and lead to the disease. It has complex clinical manifestations and is not yet curable. Gene therapy strategies for NF1 are still in the research and development stage. Existing studies on the transgenic therapy for NF1 have mainly focused on the construction and expression of the GTPase-activating protein-related domain in cells that lack of functional neurofibromin, confirming the feasibility of the transgenic therapy for NF1. Future research may focus on split adeno-associated virus (AAV) gene delivery, oversized AAV gene delivery, and the development of new vectors for targeted delivery of full-length NF1 cDNA. In addition, the gene editing tools of the new generation have great potential to treat monogenic genetic diseases such as NF1, but need to be further validated in terms of efficiency and safety.

Conclusion

Gene therapy, including both the transgenic therapy and gene editing, is expected to become an important new therapeutic approach for NF1 patients.

Neurofibromatosis type 1: Clinical characteristics and mutation spectrum in a North Indian cohort

Background

Neurofibromatosis type 1 (NF1) is a unique, highly penetrant neuro-cutaneous disorder with a wide range of manifestations. Though the clinical diagnosis of NF1 is straight forward, there can be other disorders which mimic NF1, especially its cutaneous features. Here we describe the clinical and mutation spectrum of a series of individuals whose primary diagnosis was NF1 or NF1 related disorders.

Methods

We have screened 29 unrelated individuals who fulfilled the clinical criteria of NF1. Whole exome sequencing (WES) was done in all individuals except one with suspected microdeletion syndrome with NF1 in whom Cytogenetic microarray (CMA) was done.

Results

Out of 29 suspected patients, 25 had germline pathogenic/likely pathogenic variants involving NF1 gene. Five novel and 20 known variants in coding and non-coding regions were identified, among them 7 variants were deletions (28%), 7 nonsense (28%), 3 splice-site (12%), 4 missense (16%), 2 duplications (8%) and 2 (8%) were contiguous deletions. In those where NF1 variants were not detected, 3 had neurofibromatosis type 2 (NF2) and 1 rare autosomal recessive form of Elher Danlos syndrome.

Conclusion

We hereby present the wide range of manifestations in different age groups and the mutation spectrum ranging from small scale variants to contiguous gene deletion syndromes involving NF1 gene. We highlight the usefulness of molecular testing and its importance in tumor surveillance and genetic counseling in this disorder.

An evaluation of computerized attention and executive function measures for use with school age children with neurofibromatosis type 1

The present study investigated the performance of children with neurofibromatosis type 1 on computerized assessments of attention and executive function. Relations to ADHD symptomatology were also examined. Participants included 37 children (20 male) with NF1 (9-13 years; Mage = 11.02). Participants completed the NIH Toolbox Dimensional Change Card Sort, List Sort Working Memory (LSWM), and Flanker tasks, as well as Cogstate Identification and One Back tests. ADHD symptomatology was assessed using the K-SADS. Average performance was significantly different from the normative mean on every measure, except LSWM. The NIH Toolbox Flanker and Cogstate Identification tasks detected the highest proportion of participants with at least mild difficulty, and the Cogstate Identification task detected the highest proportion of participants with severe difficulty. Analyses revealed significant relations with ADHD symptomatology for two NIH toolbox tasks. The various computerized measures of attention and executive function offer different information when working with school age children with NF1. The NIH Flanker may offer the most room for change and offers face validity, which may be beneficial for clinical trials research. However, the LSWM shows most support for relations with behavioral indicators of attention and executive challenges.

Pathogenesis and treatment of a giant occipital bone defect with meningoencephalocele in an NF1 child: case report and review of the literature

Autosomal dominantly inherited neurofibromatosis type I (NF1) is a systemic disorder caused by a mutation of a gene on chromosome 17q11.2 and characterized by multiple café-au-lait spots, lentiginous macules, Lisch nodules of the iris, and tumors of the nervous system. Bony manifestations such as scoliosis, dysplasia of the greater sphenoidal wing, tibial pseudoarthrosis, short stature, and macrocephaly have been reported in approximately 50% of patients. However, calvarial bone defects are rare. After screening 324 articles, 23 cases (12 adult and 11 pediatric patients) of occipital bone defects in NF1 patients were selected. All patients had a single/multiple bone defect over the lambdoid suture. Adjacent benign plexiform neurofibromas were observed in 14 patients (60.8%, 7 adults and 7 children); one adult patient was diagnosed with neurofibrosarcoma. Meningoencephalocele over the occipital defect was noted in 8 cases (34.78%, all adults). Cranioplasty was performed in only 17.39% of patients. Histologic examination was performed in 7 of the 15 patients with associated neurofibromas/neurofibrosarcomas. Biopsy of the bone margins surrounding the defect was performed in only one case. Pathologic examination of the herniated parieto-occipital or cerebellar tissue was not performed in any of the patients studied. We report the case of a 9-year-old girl with NF1 and a significant occipital bone defect and performed a systematic review of the relevant literature to highlight the challenges in treating this condition and to investigate the underlying mechanisms contributing to bone defects or dysplasia in NF1.

Neurofibromatosis Type 1 Vasculopathy Presenting as Branch Retinal Vein Occlusion: Case Report and Review of the Literature

Systemic vascular occlusive disease associated with neurofibromatosis type 1 (NF1) has been reported in the aortic, cerebral, renal, celiac, and mesenteric vessels and is referred to as NF1 vasculopathy. Although retinal vascular involvement in patients with NF1 usually manifests as retinal capillary hemangiomatosis, a few cases of NF1 with retinal vascular occlusive disease have also been described. Here, we report a 2-year-old girl with NF1 who presented with branch retinal vein occlusion and peripheral retinal ischemia secondary to NF1. This case demonstrates that NF1-related retinal occlusive vasculopathy may occur in very young patients and that detailed fundus examination with fluorescein angiography is necessary in all patients with NF1.

Malignant Peripheral Nerve Sheath Tumor, a rare Intraosseous Malignancy in the Mandible of a Patient with Neurofibromatosis Type 1: A Case Report

Malignant peripheral nerve sheath tumor (MPNST) is a rare malignancy of nervous tissue. The oral incidence of this lesion is extremely low. MPNST can occur sporadically or in association with neurofibromatosis. We report a rare intraosseous MPNST in the mandible of a 33-year-old female patient with neurofibromatosis type 1.

Evaluation of Molecular and Clinical Findings in Children With Neurofibromatosis Type 1: Identification of 15 Novel Variants

BACKGROUND

Neurofibromatosis type 1 (NF1) is the most common neurocutaneous disease and is caused by mutations in the NF1 gene. The most common clinical features of NF1 are pigmentary abnormalities such as café-au-lait spots and inguinal or axillary freckling, cutaneous and plexiform neurofibromas, hamartomas of the iris, optic gliomas, and bone lesions. The aim of this retrospective study was to define the clinical and molecular characteristics of a pediatric sample of NF1, as well as the mutational spectrum and genotype-phenotype correlation.

METHODS

The study included 40 children with clinically suspected NF1. The patients were screened for NF1 mutations by DNA-based sequencing. In addition, all the patients were studied by multiplex ligation-dependent probe amplification (MLPA) to identify any duplications or deletions in NF1. The demographic, clinical, and genetic features of the children were characterized.

RESULTS

A total of 40 children with NF1 were included. Of those, 28 were female and 12 were male. The mean age was 8.91 years. An NF1 variant was discovered in 28 of 40 patients (70%). Among these mutations, intronic mutations were the most frequently detected mutations; 15 of these variants had not been previously reported. Only one patient had a whole NF1 gene deletion.

CONCLUSIONS

This study expands the spectrum of mutations in the NF1 gene. This study also showed that genetic screening using both next-generation sequencing and MLPA had a positive effect on diagnosis and genetic counseling in patients with suspected NF1.

Metanephrine negative pheochromocytoma: a rare case report of dopamine-secreting tumor in an adolescent neurofibromatosis type 1 patient

Pheochromocytoma (PCC) occurs in 4% of pediatric neurofibromatosis type 1 (NF1) patients and is characterized by epinephrine and norepinephrine secretion. Herein, we report the first case of dopamine-secreting PCC in a 13-year-old patient with NF1. A left adrenal mass was incidentally found on abdominal computed tomography (CT ) during hypertension workup. Fractionated 24-hour urine metanephrine excretion was normal, but urine dopamine level was elevated. Focal 123I-metaiodobenzylguanidine uptake was observed on single-photon emission tomography/CT (SPECT/CT). Surgery was delayed due to small tumor size, vague symptoms, and increased dopamine level. After 6 months, focal significant uptake of the lesion on 6-[18F]fluoro-L-3,4-dihydroxyphenylalanine (18F-FDOPA) PET/CT increased and tumor size increased on abdominal CT. Laparoscopic resection was performed, and the mass was histologically confirmed as PCC. Currently, the vital signs of the patient are stable, urine dopamine level is normal, and there is no abnormal uptake of 18F-FDOPA PET/CT. This study reports a rare case of dopamine-secreting PCC. A multidisciplinary approach and focused examination are needed in metanephrine-negative, high-risk PCC patients.

A new era for myelin research in Neurofibromatosis type 1

Evidence for myelin regulating higher-order brain function and disease is rapidly accumulating; however, defining cellular/molecular mechanisms remains challenging partially due to the dynamic brain physiology involving deep changes during development, aging, and in response to learning and disease. Furthermore, as the etiology of most neurological conditions remains obscure, most research models focus on mimicking symptoms, which limits understanding of their molecular onset and progression. Studying diseases caused by single gene mutations represents an opportunity to understand brain dys/function, including those regulated by myelin. Here, we discuss known and potential repercussions of abnormal central myelin on the neuropathophysiology of Neurofibromatosis Type 1 (NF1). Most patients with this monogenic disease present with neurological symptoms diverse in kind, severity, and onset/decline, including learning disabilities, autism spectrum disorders, attention deficit and hyperactivity disorder, motor coordination issues, and increased risk for depression and dementia. Coincidentally, most NF1 patients show diverse white matter/myelin abnormalities. Although myelin-behavior links were proposed decades ago, no solid data can prove or refute this idea yet. A recent upsurge in myelin biology understanding and research/therapeutic tools provides opportunities to address this debate. As precision medicine moves forward, an integrative understanding of all cell types disrupted in neurological conditions becomes a priority. Hence, this review aims to serve as a bridge between fundamental cellular/molecular myelin biology and clinical research in NF1.

Reassessment of the NF1 variants of unknown significance found during the 20-year activity of a genetics diagnostic laboratory

The finding of variants of uncertain significance (VUS) in the activity of a diagnostic genetic laboratory is a common issue, which is however provisional and needs to be periodically re-evaluated, due to the continuous advancements in our knowledge of the genetic diseases. Neurofibromatosis type 1, caused by the occurrence of heterozygous pathogenic NF1 variants, is a good model for studying the evolution of VUS, due to the widespread use of genetic testing for the disease, the constant enrichment of the international databases with NF1 variants and the full adult penetrance of the disease, which makes genotyping the parents a crucial step in the diagnostic workflow. The present study retrospectively reviewed and reinterpreted the genetic test results of NF1 in a diagnostic genetic laboratory in the period from January 1, 2000 to December 31, 2020. All the VUS were reinterpreted using the 2015 consensus standards and guidelines for the interpretation. Out of 589 NF1 genetic tests which were performed in the period, a total of 85 VUS were found and reinterpreted in 72 cases (84.7%): 21 (29.2%) were reclassified as benign/likely benign, whereas 51 (70.8%) were recoded as pathogenic/likely pathogenic with a significant trend distribution (Chi square test for trend p = 0.005). Synonymous VUS have mainly been reclassified as class 1 and 2 (7/8, 87.5%), whereas missense variants have been attributed to class 4 and 5 in 38 out of the 58 cases (65.5%). These findings underline an improvement in the classification of variants over time, suggesting that a reinterpretation of the genetic tests should be routinely performed to support the physicians in the clinical diagnosis of genetic diseases.

Topical delivery of mitogen-activated protein kinase inhibitor binimetinib prevents the development of cutaneous neurofibromas in neurofibromatosis type 1 mutant mice

Cutaneous neurofibromas (cNFs) are a hallmark of patients with the neurofibromatosis type 1 (NF1) genetic disorder. These benign nerve sheath tumors, which can amount to thousands, develop from puberty onward, often cause pain and are considered by patients to be the primary burden of the disease. Mutations of NF1, encoding a negative regulator of the RAS signaling pathway, in the Schwann cell (SCs) lineage are considered to be at the origin of cNFs. The mechanisms governing cNFs development are poorly understood, and therapeutics to reduce cNFs are missing, mainly due to the lack of appropriate animal models. To address this, we designed the Nf1-KO mouse model that develops cNFs. Using this model, we found that cNFs development is a singular event and goes through 3 successive stages: initiation, progression, and stabilization characterized by changes in the proliferative and MAPK activities of tumor SCs. We found that skin trauma accelerated the development of cNFs and further used this model to explore the efficacy of the MEK inhibitor binimetinib to cure these tumors. We showed that while topically delivered binimetinib has a selective and minor effect on mature cNFs, the same drug prevents their development over long periods.

Time-frequency analyses of repetition suppression and change detection in children with neurofibromatosis type 1

Children with neurofibromatosis type 1 (NF1) are at increased risk of developing cognitive problems, including attention deficits and learning difficulties. Alterations in brain response to repetition and change have been evidenced in other genetic conditions associated with cognitive dysfunctions. Whether the integrity of these fundamental neural responses is compromised in school-aged children with NF1 is still unknown. In this study, we examined the repetition suppression (RS) and change detection responses in children with NF1 (n = 36) and neurotypical controls (n = 41) aged from 4 to 13 years old, using a simple sequence of vowels. We performed time-frequency analyses to compare spectral power and phase synchronization between groups, in the theta, alpha and beta frequency bands. Correlational analyses were performed between the neural responses and the level of intellectual functioning, as well as with behavioral symptoms of comorbid neurodevelopmental disorders measured through parental questionnaires. Children with NF1 showed preserved RS, but increased spectral power in the change detection response. Correlational analyses performed with measures of change detection revealed a negative association between the alpha-band spectral power and symptoms of inattention and hyperactivity. These findings suggest atypical neural response to change in children with NF1. Further studies should be conducted to clarify the interaction with comorbid neurodevelopmental disorders and the possible role of altered inhibitory mechanisms in this enhanced neural response.

Long-term safety and efficacy of selumetinib in children with neurofibromatosis type 1 on a phase 1/2 trial for inoperable plexiform neurofibromas

BACKGROUND

Selumetinib shrank inoperable symptomatic plexiform neurofibromas (PN) in children with neurofibromatosis type 1 (NF1) and provided clinical benefit for many in our previously published phase 1/2 clinical trials (SPRINT, NCT01362803). At the data cutoff (DCO) of the prior publications, 65% of participants were still receiving treatment. This report presents up to 5 years of additional safety and efficacy data from these studies.

METHODS

This manuscript includes data from the phase 1 and phase 2, stratum 1 study which included participants with clinically significant PN-related morbidity. Participants received continuous selumetinib dosing (1 cycle = 28 days). Safety and efficacy data through February 27, 2021 are included. PN response assessed by volumetric magnetic resonance imaging analysis: Confirmed partial response (cPR) ≥20% decrease from baseline on 2 consecutive evaluations. Phase 2 participants completed patient-reported outcome measures assessing tumor pain intensity (Numeric Rating Scale-11) and interference of pain in daily life (pain interference index).

RESULTS

For the 74 children (median age 10.3 years; range 3-18.5) enrolled, overall cPR rate was 70% (52/74); median duration of treatment was 57.5 cycles (range 1-100). Responses were generally sustained with 59% (44) lasting ≥ 12 cycles. Tumor pain intensity (n = 19, P = .015) and pain interference (n = 18, P = .0059) showed durable improvement from baseline to 48 cycles. No new safety signals were identified; however, some developed known selumetinib-related adverse events (AEs) for the first time after several years of treatment.

CONCLUSIONS

With up to 5 years of additional selumetinib treatment, most children with NF1-related PN had durable tumor shrinkage and sustained improvement in pain beyond that previously reported at 1 year. No new safety signals were identified; however, ongoing monitoring for known selumetinib-related AEs is needed while treatment continues.

Jejunal gastrointestinal stromal tumor that developed in a patient with neurofibromatosis type 1: a case report

BACKGROUND

Neurofibromatosis type 1 (NF1) is known to be associated with the frequent occurrence of unique gastrointestinal stromal tumors (GISTs), preferably occurring in the small intestine, with no mutations in the c-kit proto-oncogene or platelet-derived growth factor receptor-alpha (PDGFRA), with a high tendency for multifocal development, indolent nature, with low proliferation activity and favorable prognosis.

CASE PRESENTATION

A woman in her forties visited her local doctor complaining of menstrual pain; a large mass was detected in her lower abdomen, and she was referred to our hospital. The patient had hundreds of skin warts and café au lait spots. The patient's mother had been diagnosed with type 1 neurofibromatosis. The patient met the diagnostic criteria for NF1 and was diagnosed with NF1. Ultrasonography showed a large heterogeneous cystic mass with various echo patterns, solid compartments and multiple septations. Magnetic resonance imaging showed a multilocular cystic mass with liquid content exhibiting various intensities, including that of blood. A small round solid mass was also observed close to the cystic tumor. Contrast-enhanced computed tomography showed that the round solid mass showed strong enhancement in the early phase, unlike the cystic tumor component. Open laparotomy revealed a multicystic exophytic tumor measuring 11.5 cm originating from the jejunal wall, 20 cm distal to the duodenojejunal flexure. A solid tumor measuring 2.1 cm was also found on the anal side of the large tumor. We resected the short segment of the jejunum, including the two lesions. Microscopic findings revealed that the cystic and solid tumors consisted of spindle-shaped tumor cells showing little atypia with a fascicular or bundle arrangement. Nuclear mitosis was scarce. Immunostaining of the tumor cells showed positive staining for KIT and DOG1 and negative staining for S100 and desmin. The NF1 patient was diagnosed with multiple GISTs accompanied by intratumoral hemorrhagic denaturation arising from the jejunum. The TNM staging was pT4N0M0, stage IIIA.

CONCLUSION

We report a case of GISTs associated with NF1 that showed a jejunal origin, multifocal development and few mitotic figures. The recurrence risk, survival prognosis and need for adjuvant chemotherapy, particularly in cases where the initial GIST exhibits a very indolent pathology in NF1-related GISTs, remain to be elucidated.

Shedding New Light: Novel Therapies for Common Disorders in Children with Neurofibromatosis Type I

Neurofibromatosis type I (NF1) is a common dominantly inherited disorder, and one of the most common of the RASopathies. Most individuals with NF1 develop plexiform neurofibromas and cutaneous neurofibromas, nerve tumors caused by NF1 loss of function in Schwann cells. Cell culture models and mouse models of NF1 are being used to test drug efficacy in preclinical trials, which led to Food and Drug Administration approval for use of MEK inhibitors to shrink most inoperable plexiform neurofibromas. This article details methods used for testing in preclinical models, and outlines newer models that may identify additional, curative, strategies.

Malignant peripheral nerve sheath tumor in the pelvis: a case report

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are malignancies that arise or differentiate from or infiltrate peripheral nerves and account for approximately 5% of soft-tissue malignancies. Approximately half of MPNSTs develop in patients with neurofibromatosis type 1 (NF1), a hereditary disease. MPNSTs occur mainly in the trunk, proximal extremities, and neck, but can on rare occasion arise in or near the gastrointestinal tract, and intestinal complications have been reported. We describe herein a case with resection of an MPNST arising in the pelvic region.

CASE PRESENTATION

A 51-year-old woman had undergone repeated resections for systemic neurofibrosis associated with NF1. This time, a pelvic tumor was noted on follow-up positron emission tomography computed tomography (CT). She presented with slowly progressive radiating pain in the lower extremities and was referred to our hospital for tumor resection. Contrast-enhanced CT showed a 75 × 58-mm mass in the right greater sciatic foramen directly below a 24 × 28-mm mass. Open pelvic tumor resection was performed for pelvic neurofibroma. The obturator nerve was identified lateral to the main tumor and the sciatic nerve was identified dorsally, then dissection was performed. The closed nerve was spared, while the sciatic nerve was partially dissected and the two tumors were removed. Both tumors were elastic and hard. Pathologic findings were MPNST for the large specimen and neurofibroma with atypia for the small specimen. The patient developed temporary postoperative ileus, but is generally doing well and is currently free of recurrence or radiating pain. The patient is at high risk of recurrence and close monitoring should be continued.

CONCLUSIONS

We encountered a rare case of MPNST. Due to the high risk of recurrence, surgery with adequate margins was performed, with a requirement for appropriate follow-up.

Neurofibromatosis Type 1-Associated Plexiform Neurofibromas of the Face and Adjacent Head Regions: Topography of Lesions and Surgical Treatment Data of 179 Patients

Introduction

Facial plexiform neurofibromas (FPNF) are rare tumors frequently diagnosed in patients with neurofibromatosis type 1 (NF1), a tumor predisposition syndrome. FPNF often grows invasively and destructively, which may complicate surgical treatment. Data on the frequency, location, and surgical procedures of patients with NF1-associated FPNF are scarce. This study provides treatment data from a nationally networked reference center for the treatment of NF1 patients.

Material and Methods

The localization and treatment data of 179 NF1 patients with FPNF were analyzed. Photographically documented tumors of the study area, further determined by imaging, were manually transferred to a facial scheme and digitized. The digitized registrations of the facial extensions of the tumors of each patient were overlaid in a single image (Photoshop™), so that the file of the facial scheme contained the sum of the tumor localization. Finally, the frequency of tumor localization was indicated with a color code. The frequency of tumor extension-related coded colors was applied to outline the lesions' topography on schematic face drawings (heat map).

Results

The distribution of the tumors showed no side preference. The need for the treatment of patients with orbital/periorbital manifestations became evident in the graphic representations. Tumors do not respect anatomical units. However, the classification of the face according to dermatomes, especially the trigeminal nerve, offers indications of tumor spread and guides treatment planning. The mean number of surgical measures per patient was 2.21 (median: 1). Extensive swelling, hematoma, and delayed wound healing were all common postoperative complications.

Conclusion

The color-coded, schematic overview of the frequency distribution of cutaneous tumor spread in NF1 patients with FPNF illustrates the importance of orbital/periorbital and cheek tumor manifestations in patients' treatment needs. The imaging procedure is suitable for controlling natural tumor growth in the same way as the documentation of the post-surgical course. Repeated interventions in the region are included in surgical planning of the progressing tumor disease.

Endovascular treatment for a ruptured lumbar artery aneurysm in a patient with neurofibromatosis type 1

The present medical case report describes successful endovascular treatment via stent graft and coil packing for a ruptured lumbar artery aneurysm in a 55-year-old woman with neurofibromatosis type 1. Although less common, vasculopathy, such as an aneurysm, stenosis, rupture, and arteriovenous fistula, have been reported and can be a cause of death for patients with this disorder. However, only a few cases of a ruptured lumbar aneurysm have been reported.

The impact of changes in gadolinium-enhancement on disease progression in children with neurofibromatosis type 1-associated optic pathway glioma: a retrospective analysis

PURPOSE

There has been limited investigation of imaging features associated with visual acuity (VA) decline and initiation of treatment for patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG).

METHODS

To evaluate the association of increased gadolinium enhancement with decline in VA, initiation of chemotherapy, and tumor growth, we performed a retrospective cohort study of children diagnosed with NF1-OPG between January 2006 to June 2016. Two cohorts were defined: a new diagnosis and a longitudinal cohort. Outcomes were examined at 1 and 2 years from initial diagnosis, and 1 and 2 years from initial increase in enhancement in the longitudinal cohort.

RESULTS

Eighty patients were eligible; all 80 contributed to the new diagnosis cohort and 73 to the longitudinal cohort. Fifty-six patients (70%) demonstrated enhancing NF1-OPG at diagnosis. 39% of patients in the new diagnosis cohort and 45% of those in the longitudinal cohort developed increased enhancement during the study period. There was no significant association between increases in enhancement and VA decline in the newly diagnosed or longitudinal cohorts, as well as with initiation of treatment in the longitudinal cohort. Although there was an association of enhancement increase with treatment in the new diagnosis cohort, this association was not maintained when stratified by concurrent change in tumor size.

CONCLUSION

Increased gadolinium-enhancement independent of a concurrent increase in tumor size on MRI should not be used as a marker of NF1-OPG progression and does not appear to be associated with visual decline or initiation of chemotherapy.

A case of solitary digital glomus tumor associated with neurofibromatosis type 1

An association between glomus tumor and neurofibromatosis type 1 has been reported. It is characterized by multiple tumors and young age at onset. The early diagnosis of neurofibromatosis type 1 is important because it is associated with a high rate of malignancy. A 25-year-old man presented to our hospital with left index finger pain that had persisted for 6 years. Physical and imaging findings suggested a benign soft-tissue tumor. Surgery was performed, and the tumor was pathologically diagnosed as glomus tumor. In this case, the patient with a young-onset glomus tumor was suspected of having neurofibromatosis type 1. An additional medical examination led to the diagnosis of unrecognized neurofibromatosis type 1. We experienced a case in which the onset of a glomus tumor led to the diagnosis of neurofibromatosis type 1. Comorbid neurofibromatosis type 1 should be kept in mind when glomus tumors are diagnosed.

Childhood-Onset Refractory Hypertension Results from Neurofibromatosis Type 1 Caused by a Splicing NF1 Mutation

INTRODUCTION

Neurofibromatosis type 1 (NF-1) is caused by mutations in the NF1 gene that encodes neurofibromin, a negative regulator of RAS proto-oncogene. Approximately one-third of the reported pathogenic mutations in NF1 are splicing mutations, but most consequences are unclear. The objective of this study was to identify the pathogenicity of splicing mutation in a Chinese family with NF-1 and determine the effects of the pre-mRNA splicing mutation by in vitro functional analysis.

METHODS

Next-generation sequencing was used to screen candidate mutations. We performed a minigene splicing assay to determine the effect of the splicing mutation on NF1 expression, and three-dimensional structure models of neurofibromin were generated using SWISS-MODEL and PROCHECK methods, respectively.

RESULTS

A pathogenic splicing mutation c.479+1G>C in NF1 was found in the proband characterized by childhood-onset refractory hypertension. In vitro analysis demonstrated that c.479+1G>C mutation caused the skipping of exon 4, leading to a glutamine-to-valine substitution at position 97 in neurofibromin and an open reading frame shift terminating at codon 108. Protein modeling showed that several major domains were missing in the truncated neurofibromin protein.

CONCLUSION

The splicing mutation c.479+1G>C identified in a Chinese patient with NF-1 and childhood-onset refractory hypertension caused the skipping of exon 4 and a truncated protein. Our findings offer new evidence for the molecular diagnosis of NF-1.

Clinical, histological, and molecular features of gliomas in adults with neurofibromatosis type 1

BACKGROUND

People with NF1 have an increased prevalence of central nervous system malignancy. However, little is known about the clinical course or pathologic features of NF1-associated gliomas in adults, limiting clinical care and research.

METHODS

Adults (≥18 years) with NF1 and histologically confirmed non-optic pathway gliomas (non-OPGs) at Johns Hopkins Hospital, Memorial Sloan Kettering Cancer Center, and Washington University presenting between 1990 and 2020 were identified. Retrospective data were collated, and pathology was reviewed centrally.

RESULTS

Forty-five patients, comprising 23 females (51%), met eligibility criteria, with a median of age 37 (18-68 years) and performance status of 80% (30%-100%). Tissue was available for 35 patients. Diagnoses included infiltrating (low-grade) astrocytoma (9), glioblastoma (7), high-grade astrocytoma with piloid features (4), pilocytic astrocytoma (4), high-grade astrocytoma (3), WHO diagnosis not reached (4) and one each of gliosarcoma, ganglioglioma, embryonal tumor, and diffuse midline glioma. Seventy-one percent of tumors were midline and underwent biopsy only. All 27 tumors evaluated were IDH1-wild-type, independent of histology. In the 10 cases with molecular testing, the most common genetic variants were NF1, EGFR, ATRX, CDKN2A/B, TP53, TERT, and MSH2/3 mutation. While the treatments provided varied, the median overall survival was 24 months [2-267 months] across all ages, and 38.5 [18-109] months in individuals with grade 1-2 gliomas.

CONCLUSIONS

Non-OPGs in adults with NF1, including low-grade tumors, often have an aggressive clinical course, indicating a need to better understand the pathobiology of these NF1-associated gliomas.