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.

Icariin Promotes Osteogenic Differentiation in a Cell Model with NF1 Gene Knockout by Activating the cAMP/PKA/CREB Pathway

Neurofibromatosis type 1 is a rare autosomal dominant genetic disorder, with up to 50% of patients clinically displaying skeletal defects. Currently, the pathogenesis of bone disorders in NF1 patients is unclear, and there are no effective preventive and treatment measures. In this study, we found that knockout of the NF1 gene reduced cAMP levels and osteogenic differentiation in an osteoblast model, and icariin activated the cAMP/PKA/CREB pathway to promote osteoblast differentiation of the NF1 gene knockout cell model by increasing intracellular cAMP levels. The PKA selective inhibitor H89 significantly impaired the stimulatory effect of icariin on osteogenesis in the NF1 cell model. In this study, an osteoblast model of NF1 was successfully constructed, and icariin was applied to the cell model for the first time. The results will help to elucidate the molecular mechanism of NF1 bone disease and provide new ideas for the clinical prevention and treatment of NF1 bone disease and drug development in the future.

Blunted circadian variation of blood pressure in individuals with neurofibromatosis type 1

BACKGROUND

Cardiovascular events such as myocardial infarction and stroke are life-threatening complications associated with Neurofibromatosis type 1 (NF1). As previous studies observed an association between cardiovascular events and the loss of circadian variations of blood pressure, we investigated the 24 h circadian rhythm of blood pressure (BP) in 24 NF1 patients (10 males and 14 females, with a mean age of 39.5 years ± 14 years) by using ambulatory blood pressure monitoring (ABPM).

RESULTS

Only one-third of the patient were dippers, 50% were non-dippers, and 17% were risers. Reduced variability of systolic and diastolic nocturnal blood pressure was observed in NF1 patients compared with several studies of normotensive individuals (p = 0.024). In NF1 patients, the blunted systolic nocturnal decline was significantly associated with the number of neurofibromas (p = 0.049) and the presence of a plexiform neurofibroma (p = 0.020).

CONCLUSIONS

Most NF1 patients in this study showed a "non-dipper" pattern with a blunted nocturnal BP decline, which is considered an independent risk factor for cardiovascular events in normotensive and hypertensive individuals. Periodic monitoring of BP should be included in NF1 follow-up guidelines to diagnose masked hypertension or a non-dipper/riser pattern which would significantly increase the morbidity and mortality of NF1 patients to implement therapeutic strategies.

Treatment decisions and the use of MEK inhibitors for children with neurofibromatosis type 1-related plexiform neurofibromas

Neurofibromatosis type 1 (NF1), the most common tumor predisposition syndrome, occurs when NF1 gene variants result in loss of neurofibromin, a negative regulator of RAS activity. Plexiform neurofibromas (PN) are peripheral nerve sheath tumors that develop in patients with NF1 and are associated with substantial morbidity and for which, until recently, the only treatment was surgical resection. However, surgery carries several risks and a proportion of PN are considered inoperable. Understanding the genetic underpinnings of PN led to the investigation of targeted therapies as medical treatment options, and the MEK1/2 inhibitor selumetinib has shown promising efficacy in pediatric patients with NF1 and symptomatic, inoperable PN. In a phase I/II trial, most children (approximately 70%) achieved reduction in tumor volume accompanied by improvements in patient-reported outcomes (decreased tumor-related pain and improvements in quality of life, strength, and range of motion). Selumetinib is currently the only licensed medical therapy indicated for use in pediatric patients with symptomatic, inoperable NF1-PN, with approval based on the results of this pivotal clinical study. Several other MEK inhibitors (binimetinib, mirdametinib, trametinib) and the tyrosine kinase inhibitor cabozantinib are also being investigated as medical therapies for NF1-PN. Careful consideration of multiple aspects of both disease and treatments is vital to reduce morbidity and improve outcomes in patients with this complex and heterogeneous disease, and clinicians should be fully aware of the risks and benefits of available treatments. There is no single treatment pathway for patients with NF1-PN; surgery, watchful waiting, and/or medical treatment are options. Treatment should be individualized based on recommendations from a multidisciplinary team, considering the size and location of PN, effects on adjacent tissues, and patient and family preferences. This review outlines the treatment strategies currently available for patients with NF1-PN and the evidence supporting the use of MEK inhibitors, and discusses key considerations in clinical decision-making.

Improvement of synaptic plasticity and cognitive function in RASopathies-a monocentre, randomized, double-blind, parallel-group, placebo-controlled, cross-over clinical trial (SynCoRAS)

BACKGROUND

Cognitive impairment is a common medical issue in rat sarcoma (RAS) pathway disorders, so-called RASopathies, like Neurofibromatosis type 1 (NF1) or Noonan syndrome (NS). It is presumed to be caused by impaired synaptic plasticity. In animal studies, pathway-specific pharmacological interventions with lovastatin (LOV) and lamotrigine (LTG) have been shown to improve synaptic plasticity as well as cognitive function. The aim of this clinical trial is to translate the findings of animal studies to humans and to probe the effect of lovastatin (NS) and lamotrigine (NS and NF1) on synaptic plasticity and cognitive function/alertness in RASopathies.

METHODS

Within this phase IIa, monocentre, randomized, double-blind, parallel-group, placebo-controlled, cross-over clinical trial (syn. SynCoRAS), three approaches (approaches I-III) will be carried out. In patients with NS, the effect of LTG (approach I) and of LOV (approach II) is investigated on synaptic plasticity and alertness. LTG is tested in patients with NF1 (approach III). Trial participants receive a single dose of 300 mg LTG or placebo (I and III) and 200 mg LOV or placebo (II) daily for 4 days with a cross-over after at least 7 days. Synaptic plasticity is investigated using a repetitive high-frequency transcranial magnetic stimulation (TMS) protocol called quadri-pulse theta burst stimulation (qTBS). Attention is examined by using the test of attentional performance (TAP). Twenty-eight patients are randomized in groups NS and NF1 with n = 24 intended to reach the primary endpoint (change in synaptic plasticity). Secondary endpoints are attention (TAP) and differences in short interval cortical inhibition (SICI) between placebo and trial medication (LTG and LOV).

DISCUSSION

The study is targeting impairments in synaptic plasticity and cognitive impairment, one of the main health problems of patients with RASopathies. Recent first results with LOV in patients with NF1 have shown an improvement in synaptic plasticity and cognition. Within this clinical trial, it is investigated if these findings can be transferred to patients with NS. LTG is most likely a more effective and promising substance improving synaptic plasticity and, consecutively, cognitive function. It is expected that both substances are improving synaptic plasticity as well as alertness. Changes in alertness may be a precondition for improvement of cognition.

TRIAL REGISTRATION

The clinical trial is registered in ClinicalTrials.gov (NCT03504501; https://www.

CLINICALTRIALS

gov ; date of registration: 04/11/2018) and in EudraCT (number 2016-005022-10).

Plexiform neurofibromatosis of the bladder leading to cystectomy: A rare complication of von Recklinghausen disease

We report a 20-year-old man with neurofibromatosis type 1 presenting with frequent episodes of suprapubic pain. The episodes started 6 months ago, occurred 1 h a day, and were not related to urination. A prostate-sparing cystectomy with orthotopic diversion was performed. Histopathological assessment of the specimen confirmed bladder plexiform neurofibromatosis.

Dynamic contrast-enhanced MRI and sequential CT findings of metaplastic breast carcinoma in neurofibromatosis type 1: A case report

Metaplastic breast carcinoma in neurofibromatosis type 1 is extremely rare. There are few reports about dynamic contrast-enhanced MRI findings and sequential CT findings of metaplastic breast carcinoma in neurofibromatosis type 1. Herein, we report imaging findings, including dynamic contrast-enhanced MRI and sequential CT, of metaplastic breast carcinoma in an 82-year-old woman with neurofibromatosis type 1. Short tau inversion recovery image revealed an oval mass with a circumscribed margin that exhibited moderate intensity with partially hyperintense area inside, and T1-weighted imaging revealed a spotty hyperintense area. The solid component of the mass showed heterogeneous enhancement and the time-intensity curve had a fast/washout pattern with restricted diffusion. In addition, multiple neurofibromas were observed. Sequential CT revealed that the diameter of the mass doubled in 3 months without apparent lymph node metastasis. Because detection of metaplastic breast carcinoma in neurofibromatosis type 1 tends to be delayed due to multiple neurofibromas, characteristic MRI findings suggestive of metaplastic breast carcinoma and sequential CT findings are important for early treatment of metaplastic breast carcinoma in patients with neurofibromatosis type 1.

Health-related quality of life of children with neurofibromatosis type 1: Analysis of proxy-rated PedsQL and CHQ questionnaires

This study aims to (1) investigate health-related quality of life (HRQoL) in children with Neurofibromatosis Type 1 (NF1) using the Pediatric Quality of Life inventory (PedsQL) and the Child Health Questionnaire (CHQ); and (2) compare the psychometric properties and content of these questionnaires in NF1 patients. PedsQL and CHQ proxy-reports were administered to parents/caregivers of 160 patients with NF1 aged 5-12 years. HRQoL scores were compared with Dutch population norms using independent t-tests. Psychometric properties (feasibility and reliability) were assessed by floor/ceiling effects and Cronbach's alpha coefficient. A principal component analysis (PCA) with varimax rotation was performed to identify the data's internal structure. By content mapping, we identified unique constructs of each questionnaire. Proxy-reported HRQoL was significantly lower on all PedsQL subscales for children aged 5-7 years, and on 4/6 subscales for children aged 8-12 years compared to norms. Significantly lower HRQoL was reported on 6/14 CHQ subscales (children 5-7 years) and 9/14 subscales (children 8-12 years). The PedsQL showed slightly better feasibility and reliability. The PCA identified two components, representing psychosocial and physical aspects of HRQoL, explaining 63% of total variance. Both questionnaires showed relevant loadings on both components. The CHQ subscales concerning parents and family were considered unique contributions. Proxy-reported HRQoL of children with NF1 is significantly lower compared to norms on multiple domains. Both questionnaires adequately measure HRQoL in children with NF1. However, the PedsQL has slightly better psychometric properties, while the CHQ covers a unique dimension of HRQoL associated with disease impact on parents and family.

Diagnosis of neonatal neurofibromatosis type 1: a case report and review of the literature

BACKGROUND

Neurofibromatosis Type 1 (NF1) is a rare genetic disorder characterized with the development of multiple benign tumors on the nerves and skin.

CASE PRESENTATION

This report described a neonatal case with a large mass observed on the left side of the maxillofacial and cervical region at birth. Meantime, multiple cafe-au-lait macules (CALMs) were seen on the trunk and both lower extremities.

CONCLUSIONS

In this case, the clinical features of the rare NF1 neonate are discussed along with its ultrasound findings.

Bone Mineral Density in Neurofibromatosis Type 1: A Systematic Review and Meta-Analysis

To assess BMD in patients with neurofibromatosis type 1 (NF1) using systematic review and meta-analysis technique. Potentially eligible studies were identified from Medline and EMBASE databases from inception to February 2023 using search strategy that comprised terms for "Bone mineral density" and Neurofibromatosis type 1″. Eligible study must include adult or pediatric patients with NF1. The study must report mean Z-score with variance of total body, lumbar spine, femoral neck or total hip BMD of the studied patients. Point estimates with standard errors were retrieved from each study and were combined using the generic inverse variance method. A total of 1,165 articles were identified. After systematic review, 19 studies were included. The meta-analysis revealed that patients with NF1 had negative mean Z-scores for total body BMD (pooled mean Z-score -0.808; 95%CI, -1.025 to -0.591) and BMD at lumbar spine (pooled mean Z-score -1.104; 95%CI, -1.376 to -0.833), femoral neck (pooled mean Z-score -0.726; 95%CI, -0.893 to -0.560) and total hip (pooled mean Z-score -1.126; 95%CI, -2.078 to -0.173). The subgroup meta-analysis in pediatric patients aged < 18 years revealed that patients with NF1 had negative mean Z-scores for lumbar spine BMD (pooled mean Z-score -0.938; 95%CI, -1.299 to -0.577) and femoral neck BMD (pooled mean Z-score -0.585; 95%CI, -0.872 to -0.298). The current meta-analysis found that patients with NF1 had low Z-scores although the degree of low BMD may not be of clinical significance. The results do not support the role of early BMD screening in children and young adults with NF1.

Delayed emergence from anesthesia caused by an intraoperative cerebral embolism of a malignant peripheral nerve sheath tumor in a neurofibromatosis type 1 patient: a case report

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas which commonly arise from neurofibromatosis type 1. Lung metastases of the tumors are well-known, but intraoperative cerebral tumor embolisms of MPNSTs have not been reported in literature.

CASE PRESENTATION

A 52-year-old female patient with neurofibromatosis type 1 underwent a right lung partial resection for lung tumors. She was extubated after adequate recovery of spontaneous breathing; however, she could not respond to verbal commands. In the intensive care unit, her neurological examination revealed conjugate eye deviation, right hemiparalysis, and aphasia. Magnetic resonance imaging revealed acute cerebral ischemia, so she underwent an endovascular thrombectomy. The histopathological diagnosis of emboli was a MPNST, which was identical with that of the resected lung tumor.

CONCLUSION

We report the first case of delayed emergence caused by a cerebral tumor embolism of MPNST during partial lung resection.

Portal cavernoma in type 1 neurofibromatosis: A fortuitous or causal association?

Neurofibromatosis type 1 (NF-1) is a multisystem genetic disorder affecting the NF1 tumor suppressor gene. Patients typically develop superficial (cutaneous) and internal (plexiform) neurofibromas. The latter may rarely involve the liver locating in the hilum and encasing the portal vessels, leading to portal hypertension. Vascular abnormalities (NF-I vasculopathy) are a well-recognized manifestation of NF-1. Although the pathogenesis is not well-known, NF-1 vasculopathy involves arteries of both peripheral and cerebral territories, with venous thrombosis being exceptionally reported. Portal venous thrombosis (PVT) is the leading cause of portal hypertension in childhood and has been associated with several risk factors. Nevertheless, predisposing conditions remain unknown in more than 50% of the cases. The treatment options are limited, and its management is nonconsensual in the pediatric age. We report the case of a 9-year-old boy with clinically and genetically confirmed NF-1, diagnosed with portal venous cavernoma after an episode of gastrointestinal bleeding. There were no identifiable risk factors for PVT and intrahepatic peri-hilar plexiform neurofibroma was excluded by MRI imaging. To the best of our knowledge, this is the first report of PVT in NF-1. We speculate that NF-1 vasculopathy may have been a pathogenic factor, or instead, it was a fortuitous association.

Using a semi-automated approach to quantify Unidentified Bright Objects in Neurofibromatosis type 1 and linkages to cognitive and academic outcomes

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous syndrome that affects multiple organ systems resulting in widespread symptoms, including cognitive deficits. In addition to the criteria required for an NF1 diagnosis, approximately 70% of children with NF1 present with Unidentified Bright Objects (UBOs) or Focal Areas of Signal Intensity, which are hyperintense bright spots seen on T2-weighted magnetic resonance images and seen more prominently on FLAIR magnetic resonance images (Sabol et al., 2011). Current findings relating the presence/absence, quantities, sizes, and locations of these bright spots to cognitive abilities are mixed. To contribute to and hopefully disentangle some of these mixed findings, we explored potential relationships between metrics related to UBOs and cognitive abilities in a sample of 28 children and adolescents with NF1 (M=12.52 years; SD=3.18 years; 16 male). We used the Lesion Segmentation Tool (LST) to automatically detect and segment the UBOs. The LST was able to qualitatively and quantitatively reliably detect UBOs in images of children with NF1. Using these automatically detected and segmented lesions, we found that while controlling for age, biological sex, perceptual IQ, study, and scanner, "total UBO volume", defined as the sum of all the voxels representing all of the UBOs for each participant, helped explain differences in word reading, phonological awareness, and visuospatial skills. These findings contribute to the emerging NF1 literature and help parse the specific deficits that children with NF1 have, to then help improve the efficacy of reading interventions for children with NF1.

Unilateral chronic angle-closure glaucoma in a pediatric patient with neurofibromatosis: a case report

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease that causes multi-system damage. It is rarely associated with angle-closure glaucoma, especially in pediatric patients. We herein report a case of unilateral chronic angle-closure glaucoma in a patient with NF1. A 5-year-old girl with a large subcutaneous soft mass and multiple scattered coffee-milk spots presented with low vision, increased intraocular pressure, and angle closure in her right eye. Lisch nodules were seen in both eyes. In her right eye, ectropion uveae was observed at the top and bottom margins of the pupil. Magnetic resonance imaging of the skull and orbit revealed no abnormalities. Finally, trabeculectomy was performed on the right eye, after which the right eye showed a stable intraocular pressure. NF1 combined with angle-closure glaucoma is rare and easily missed in the clinical setting. Early diagnosis and treatment may achieve good results.

Neurobehavioral sex-related differences in Nf1+/- mice: female show a "camouflaging"-type behavior

BACKGROUND

Neurofibromatosis type 1 (NF1) is an inherited neurocutaneous disorder associated with neurodevelopmental disorders including autism spectrum disorder (ASD). This condition has been associated with an increase of gamma-aminobutyric acid (GABA) neurotransmission and, consequently, an excitation/inhibition imbalance associated with autistic-like behavior in both human and animal models. Here, we explored the influence of biological sex in the GABAergic system and behavioral alterations induced by the Nf1^+/- mutation in a murine model.

METHODS

Juvenile male and female Nf1^+/- mice and their wild-type (WT) littermates were used. Hippocampus size was assessed by conventional toluidine blue staining and structural magnetic resonance imaging (MRI). Hippocampal GABA and glutamate levels were determined by magnetic resonance spectroscopy (MRS), which was complemented by western blot for the GABA(A) receptor. Behavioral evaluation of on anxiety, memory, social communication, and repetitive behavior was performed.

RESULTS

We found that juvenile female Nf1^+/- mice exhibited increased hippocampal GABA levels. Moreover, mutant female displays a more prominent anxious-like behavior together with better memory performance and social behavior. On the other hand, juvenile Nf1^+/- male mice showed increased hippocampal volume and thickness, with a decrease in GABA(A) receptor levels. We observed that mutant males had higher tendency for repetitive behavior.

CONCLUSIONS

Our results suggested a sexually dimorphic impact of Nf1^+/- mutation in hippocampal neurochemistry, and autistic-like behaviors. For the first time, we identified a "camouflaging"-type behavior in females of an animal model of ASD, which masked their autistic traits. Accordingly, like observed in human disorder, in this animal model of ASD, females show larger anxiety levels but better executive functions and production of normative social patterns, together with an imbalance of inhibition/excitation ratio. Contrary, males have more externalizing disorders, such as hyperactivity and repetitive behaviors, with memory deficits. The ability of females to camouflage their autistic traits creates a phenotypic evaluation challenge that mimics the diagnosis difficulty observed in humans. Thus, we propose the study of the Nf1^+/- mouse model to better understand the sexual dimorphisms of ASD phenotypes and to create better diagnostic tools.

Malignant peripheral nerve sheath tumor on a patient with a maternally inherited novel NF1 gene pathogenic germline variant: Case report

INTRODUCTION

Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome caused by pathogenic variants in NF1, which negatively regulates the RAS pathway. Knowledge of the genotype-phenotype correlation in this disease is an important tool for prognostic evaluation and early detection of malignant peripheral nerve sheath tumors (MPNST), present in approximately 10% of these patients. We present the case of a teenager with a left jaw MPNST and a previously unreported germline pathogenic variant on NF1.

CASE PRESENTATION

An 11-year-old female with a NF1 clinical diagnosis was referred to our hospital with a MPNST in an advanced state. A previously unreported NF1 pathogenic variant was obtained (GRCh37: NM_182493.2 c.3299C>G, p.Ser1100*). Despite great efforts from the surgical and medical teams, the tumor progression couldn't be halted, resulting in the patient's death.

DISCUSSION

As MPNSTs are refractory to current treatment regimens, early diagnosis, and development of new therapies, such as MEK inhibitors, is necessary for reducing morbidity and mortality within NF1 patients. This increases the importance of a more widespread genetic testing strategy.

CONCLUSION

The report of a novel NF1 pathogenic variant in a patient with maternally inherited neurofibromatosis type 1 and a MPNST increases the knowledge of the genotype-phenotype correlation in the disease.

Neurofibromatosis type 1 with multiple gastrointestinal stromal tumors: A case report

BACKGROUND

Neurofibromatosis type 1 (NF1) is characterized by café-au-lait patches on the skin and the presence of neurofibromas. Gastrointestinal stromal tumor (GIST) is the most common non-neurological tumor in NF1 patients. In NF1-associated GIST, KIT and PDGFRA mutations are frequently absent and imatinib is ineffective. Surgical resection is first-line treatment.

CASE SUMMARY

A 56-year-old woman with NF1 was hospitalized because of an incidental pelvic mass. Physical examination was notable for multiple café-au-lait patches and numerous subcutaneous soft nodular masses of the skin of the head, face, trunk, and limbs. Her abdomen was soft and nontender. No masses were palpated. Digital rectal examination was unremarkable. Abdominal computed tomography was suspicious for GIST or solitary fibrous tumor. Laparoscopy was performed, which identified eight well-demarcated masses in the jejunum. All were resected and pathologically diagnosed as GISTs. The patient was discharged on day 7 after surgery without complications. No tumor recurrence was evident at the 6-mo follow-up.

CONCLUSION

Laparoscopy is effective for both diagnosis and treatment of NF1-associated GIST.

A preliminary study of the different memory systems in neurofibromatosis type 1: What is impaired and what is spared?

BACKGROUND

Since 1990's, the cognitive profile of children with a neurofibromatosis type 1 (NF1) has been refined by many different studies. Children with NF1 may exhibit a variety of cognitive dysfunctions. Memory difficulties have been reported, but the results are contradictory and, compared to other cognitive functions, memory has been less evaluated.

OBJECTIVE

The aim of this study was to investigate the memory profile in NF1 with a particular population, children with NF1 without attention deficit hyperactivity disorder (ADHD).

METHODS

Eighteen children with NF1 without ADHD and eighteen typically developing aged from 8 to 12.6 years were compared in terms of both their verbal and visual working memory, anterograde memory, and procedural perceptual-motor memory. We also assessed semantic and autobiographical memory.

RESULTS

Our results indicate the existence of memory difficulties in children with NF1 without ADHD in verbal working and anterograde memory but not in terms of the visual domain. They also experienced difficulties recalling personal memories but these were improved by cueing. However, semantic memory and procedural perceptual-motor memory was preserved.

CONCLUSIONS

These results highlight a difference between memory systems in children with NF1 without ADHD and the importance to assess the different memory systems, the nature of information and the processes in long-term memory in NF1 population. However, our results raise questions about the possible links between these difficulties and the executive functions. The specifics of memory profile in children with NF1 must be taken into consideration in these children's clinical follow-up, in order to understand their learning difficulties and to make adaptations to their care.

Lymphomas in patients with neurofibromatosis type 1 (NF1): another malignancy in the NF1 syndrome?

Neurofibromatosis type 1 (NF1) is an autosomal dominant multisystem syndrome caused by mutations in the neurofibromin 1 (NF1) gene that encodes for the protein neurofibromin acting as a tumour suppressor. Neurofibromin functions primarily as a GTPase-activating protein for the Ras family of oncogenes, which activates many signalling pathways for cell proliferation and differentiation; without neurofibromin, Ras is constitutively activated, thereby turning on many downstream signalling pathways related to oncogenesis. Patients with NF1 have a well known predisposition for certain types of malignancies including malignant peripheral nerve sheath tumours, gliomas, and breast cancers, as well as a potential association of NF1 with lymphoproliferative disorders such as lymphomas. In this article, we review the pathophysiology and tumourigenesis of NF1, previously reported cases of cutaneous lymphomas in NF1 patients along with our case demonstration of a NF1-associated scalp B-cell lymphoma, and NF1-associated extra cutaneous lymphomas. The diagnosis of lymphomas particularly cutaneous lymphomas may be difficult in NF1 patients as they often have skin lesions and/or cutaneous/subcutaneous nodules or tumours like neurofibromas, which raises the possibility of underdiagnosed cutaneous lymphomas in NF1 patients. We also comprehensively discuss the association between NF1 and lymphomas. In summary, most studies support a potential association between NF1 and lymphomas. Further investigation is needed to clarify the association between NF1 and lymphomas in order to bring clinical awareness of possibly underdiagnosed NF1-associated lymphomas and individualised management of NF1 patients to practice.

Comprehensive neurological evaluation of a cohort of patients with neurofibromatosis type 1 from a single institution

Neurofibromatosis type 1 (NF1) is a phenotypically heterogenous multisystem cancer predisposition syndrome manifesting in childhood and adolescents. Central nervous system (CNS) manifestations include structural, neurodevelopmental, and neoplastic disease. We aimed to (1) characterize the spectrum of CNS manifestations of NF1 in a paediatric population, (2) explore radiological features in the CNS by image analyses, and (3) correlate genotype with phenotypic expression for those with a genetic diagnosis. We performed a database search in the hospital information system covering the period between January 2017 and December 2020. We evaluated the phenotype by retrospective chart review and imaging analysis. 59 patients were diagnosed with NF1 [median age 10.6 years (range, 1.1-22.6); 31 female] at last follow-up, pathogenic NF1 variants were identified in 26/29. 49/59 patients presented with neurological manifestations including 28 with structural and neurodevelopmental findings, 16 with neurodevelopmental, and 5 with structural findings only. Focal areas of signal intensity (FASI) were identified in 29/39, cerebrovascular anomalies in 4/39. Neurodevelopmental delay was reported in 27/59 patients, learning difficulties in 19/59. Optic pathway gliomas (OPG) were diagnosed in 18/59 patients, 13/59 had low-grade gliomas outside the visual pathways. 12 patients received chemotherapy. Beside the established NF1 microdeletion, neither genotype nor FASI were associated with the neurological phenotype. NF1 was associated with a spectrum of CNS manifestations in at least 83.0% of patients. Regular neuropsychological assessment complementing frequent clinical and ophthalmologic testing for OPG is necessary in the care of each child with NF1.