Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

Glioma-Induced Seizure in a Neurofibromatosis Type 1 Patient: A Case Report

Neurofibromatosis type 1 (NF-1), also known as Von Recklinghausen's disease, is an autosomal-dominant disease that is characterized by high-frequency mutations leading to multiple benign tumors called neurofibromas and café au lait spots on the skin. Although NF-1 mainly affects the nervous system, it can have multisystem involvement as well, associated with the cardiovascular, orthopedic, gastrointestinal, and dermatologic systems. Psychiatric complications like anxiety, dysthymia, and depression have also been reported in patients with NF-1. The prevalence of this disorder is one in 3,000 births. NF-1 patients have a higher prevalence of seizures compared to the general population.

A 20-year-old male with a diagnosis of NF-1 at the age of three months presented to the emergency room (ER) of a local hospital for the evaluation of an unwitnessed seizure characterized by loss of consciousness and bladder control. MRI of the brain without contrast revealed hyperintensities in the mesial temporal lobe bilaterally, with a hyperintense FLAIR lesion in the splenium of the corpus callosum. The patient exhibited sudden aggression and combativeness while in the ER and also experienced a second seizure, which prompted immediate intubation. A second MRI with contrast confirmed the presence of the lesion. The patient also underwent electroencephalogram (EEG) monitoring later during his hospital stay, the results of which were unremarkable.

This case report discusses an adult male with NF-1 and a tumor of the splenium of the corpus callosum. The displayed imaging suggested a possible etiology for high seizure frequency in patients with NF-1 compared to the general population.

Targeted Therapies for the Neurofibromatoses

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2. Successful inhibition of MEK for patients with neurofibromatosis type 1 and progressive optic pathway gliomas or plexiform neurofibromas has been a significant advancement in patient care. Similar success for the malignant NF1 tumors, such as high-grade gliomas and malignant peripheral nerve sheath tumors, has not yet been achieved; nor has significant progress been made for patients with either neurofibromatosis type 2 or schwannomatosis, although efforts are ongoing.

Optic pathway glioma and the sex association in neurofibromatosis type 1: a single-center study

Background

Low-grade optic pathway glioma (OPG) develops in 15–20% of children with neurofibromatosis type 1 (NF1). OPGs are symptomatic in 30–50% and one-third of these require treatment. A few studies have suggested female sex as a risk factor for visual impairment associated with NF1-OPG. This descriptive study investigated the correlation between NF1-OPG growth, sex and visual impairment.

Method

We based our cross-sectional study on a systematic, retrospective data collection in a NF1 cohort of children and adolescents below 21 years of age followed at Center for Rare Diseases, Aarhus University Hospital, Denmark. For each patient with OPG a medical chart review was performed including demographics, ophthalmological examinations and magnetic resonance imaging (MRI) of OPG.

Results

Of 176 patients with NF1 (85 females, 91 males), we identified 21 patients with OPG (11.9%) with a preponderance of females, p = 0.184. Eight females (62%) and one male (13%) had visual impairment at the last ophthalmological evaluation. Five out of 21 children with OPG (24%) underwent diagnostic MRI because of clinical findings at the ophthalmological screening. Nine children (43%) had symptoms suggestive of OPG and seven (33%) experienced no OPG-related symptoms before the diagnostic MRI. Of eight children diagnosed with OPG ≤ two years of age, one had visual impairment. Of 13 children diagnosed > two years of age, eight had visual impairment; in each group, four of the children were treated with chemotherapy. The study suggested no correlation between NF1-OPG growth and sex.

Conclusion

Our data suggest sex as a risk factor for visual impairment, while an OPG diagnose ≤ two years of age was a protective factor for visual impairment. Females with NF1-OPG had a higher prevalence of visual impairment outcome compared to males. Interestingly, our data also suggest a better response to treatment in children with OPG diagnosed ≤ two years of age compared to older children. The findings in our study suggest sex as a potential prognostic factor for visual impairment.

Brain Cancers in Genetic Syndromes

PURPOSE OF REVIEW

Although genetic conditions that cause primary central nervous system tumors are rare, their pathophysiology influences both treatment and surveillance. This article reviews the most frequently occurring genetic conditions associated with brain cancers and highlights the most recent therapeutic approaches in the treatment of Lynch syndrome (and other disorders of the mismatch repair system), neurofibromatosis 1, and Li-Fraumeni syndrome.

RECENT FINDINGS

Recent advances in molecular diagnostics have considerably improved the ability to diagnose genetic conditions in people with primary brain tumors. The common application of next-generation sequencing analyses of tissue increases the frequency with which clinicians are forced to address the possibility of an underlying genetic condition based on tissue molecular findings. Clinicians must be aware of the clinical presentation of genetic conditions predisposing to brain tumors in order to discern which patients are appropriate for germline genetic testing. Advances in therapeutics for specific genetic variants are increasingly available, and accurately diagnosing an underlying genetic condition may directly impact patient outcomes.

Impact of systemic anticancer therapy in pediatric optic pathway glioma on visual function: A systematic review

Pediatric optic pathway glioma (OPG) can seriously decrease visual function in the case of progression. Systemic anticancer therapy (SAT) is considered the treatment of first choice for unresectable OPG. New SAT modalities for the treatment of progressive OPG have been introduced in the last decade, including VEGF and MAPK pathway inhibition. This systematic review evaluated the effect of SAT on change in visual acuity and visual field in OPG. A systematic review was performed on SAT for OPG (January 1990 to August 2020). MEDLINE and EMBASE (Ovid) were searched for studies reporting on change in visual acuity and visual field after treatment with SAT for OPG. Overall, 11 series, including 358 patients, fulfilled the eligibility criteria. After follow-up of median 3.7 years (range: cessation of SAT- 8.2 years), improvement in binocular VA was found in 0-45% of studies, stability in 18-77% and a decrease in 0-82%. Two studies reported on change in visual field (improvement in 19% and 71% of patients), although either the change was not defined or the testing strategy was lacking. Considerable heterogeneity was present among the included studies, such as variety in the combinations of SAT administered, status of neurofibromatosis type 1, definition regarding change in visual acuity, 1- or 2-eye analysis, diversity in anatomic location, and extent of follow-up, all of which made meta-analysis inappropriate. This systematic review suggests that the impact of SAT in OPG on visual function is still unclear. The wide ranges reported on the efficacy of SAT and the observed heterogeneity highlight the need for prospective studies with uniform definitions of outcome parameters.

MEK inhibitors in RASopathies

PURPOSE OF REVIEW

An early understanding of the role of the Ras/Raf/MEK/ERK signalling pathway in regulating cell proliferation has set the stage for the development of several potent and selective MEK inhibitors (MEKi). MEKi represent promising therapies for RAS-driven neoplasias and RASopathies associated with increased Ras/MAPK activity.

RECENT FINDINGS

Neurofibromatosis 1 (NF1) is a prototypic RASopathy in which early-phase clinical trials with MEKi have been successful in the treatment of plexiform neurofibromas (pNF) and low-grade gliomas (LGGs). The phase 2 trial (SPRINT) of selumetinib in pNF resulted in at least 20% reduction in the size of pNF from baseline in 71% of patients and was associated with clinically meaningful improvements. On the basis of this trial, selumetinib (Koselugo) received FDA approval for children 2 years of age and older with inoperable, symptomatic pNF. The phase 2 trial of selumetinib in LGG resulted in 40% partial response and 96% of patients had 2 years of progression-free survival.

SUMMARY

Given the potential of MEK inhibition as an effective and overall well tolerated medical treatment, the use of targeted agents in the NF1 population is likely to increase considerably. Future work on non-NF1 RASopathies should focus on developing preclinical models and defining endpoints for measurement of efficacy in order to conduct clinical trials.

Surgical techniques in the management of supratentorial pediatric brain tumors: 10 years' experience at a tertiary care center in the Middle East

Background:

The goal of this retrospective study is to present the first epidemiological data on pediatric supratentorial central nervous system (CNS) tumors in Lebanon and to review the various surgical management strategies used.

Methods:

We conducted a retrospective case series of all pediatric patients who presented with a supratentorial CNS tumor and underwent surgery at our institution between 2006 and 2016. We collected and analyzed demographic characteristics, tumor location, clinical manifestations, histopathology, and surgical management strategies and outcome, and discussed them after dividing the tumors as per location and in view of published literature.

Results:

Ninety-nine children were studied with a male-to-female ratio of 2.3:1 and a mean age of 8.5 years. The most common location was convexity (44%) and included low-grade and high-grade glial tumors, along with other miscellaneous lesions. The next location was sellar/diencephalic (34%), including craniopharyngiomas, hypothalamic/optic pathway/thalamic gliomas, hamartomas, and pituitary/Rathke’s cyst, where there was notable use of endoscopic techniques (21%). Tumors in the pineal region (13%) were tectal gliomas, germ cell tumors, and pineoblastomas and were mostly treated endoscopically. The last group was lateral intraventricular tumors (8%) and was mostly choroid plexus lesions and ependymomas. Overall, the surgical objective was achieved in 95% with mild/moderate complications in 17%.

Conclusion:

A variety of pathologies may affect the pediatric population in the supratentorial region. Different surgical strategies, including microsurgical and endoscopic techniques, may be employed to remove, debulk, or biopsy these tumors depending on their location, suspected diagnosis, prognosis, and the need for treatment of possible associated hydrocephalus.

Neurosurgical experience of managing optic pathway gliomas

BACKGROUND

Optic pathway gliomas (OPGs), also known as visual pathway gliomas, are debilitating tumors that account for 3-5% of all pediatric brain tumors. They are most commonly WHO grade 1 pilocytic astrocytomas and frequently occur in patients with neurofibromatosis type 1. The location of these tumors results in visual loss and blindness, endocrine and hypothalamic dysfunction, hydrocephalus, and premature death. Their involvement of the visual pathways and proximity to other eloquent brain structures typically precludes complete resection or optimal radiation dosing without incurring significant neurological injury. There are various surgical interventions that can be performed in relation to these lesions including biopsy, cerebrospinal fluid diversion, and partial or radical resection, but their role is a source of debate. This study catalogues our surgical experience and patient outcomes in order to support decision-making in this challenging pathology.

METHODS

A retrospective review of all cases of OPGs treated in a single center from July 1990 to July 2020. Data was collected on patient demographics, radiographic findings, pathology, and management including surgical interventions. Outcome data included survival, visual function, endocrine, and hypothalamic dysfunction.

RESULTS

One hundred twenty-one patients with OPG were identified, and 50 of these patients underwent a total of 104 surgical procedures. These included biopsy (31), subtotal or gross total resection (20 operations in 17 patients), cyst drainage (17), Ommaya reservoir insertion (9), or cerebrospinal fluid diversion (27). During the study period, there was 6% overall mortality, 18% hypothalamic dysfunction, 20% endocrine dysfunction, and 42% had some cognitive dysfunction. At diagnosis 75% of patients had good or moderate visual function in at least one eye, and overall, this improved to 83% at the end of the study period. In comparison the worst eye had good or moderate visual function in 56%, and this reduced to 53%. Baseline and final visual function were poorer in patients who had a surgical resection, but improvements in vision were still found-particularly in the best eye.

DISCUSSION/CONCLUSION

OPG are debilitating childhood tumor that have lifelong consequences in terms of visual function and endocrinopathies/hypothalamic dysfunction; this can result in substantial patient morbidity. Decisions regarding management and the role of surgery in this condition are challenging and include cerebrospinal fluid diversion, biopsy, and in highly select cases cystic decompression or surgical resection. In this paper, we review our own experience, outcomes, and surgical philosophy.

Comparison of two surgical methods for the treatment of optic pathway gliomas in the intraorbital segment: an analysis of long-term clinical follow-up, which evaluates the surgical outcomes

BACKGROUND

This study analyzes two kinds of surgical methods for the treatment of optic pathway gliomas (OPGs) in the intraorbital segment, as well as the surgical outcomes of OPGs.

METHODS

The clinical data of 86 patients with OPGs treated in our center was analyzed retrospectively, and the clinical symptoms, treatment methods, and follow-up results were recorded.

RESULTS

For OPGs in the intraorbital segment, the optic nerve sheath incision was performed to remove a tumor while retaining the optic nerve sheath in Group 1 (n=36). The optic nerve sheath and the tumor were simultaneously removed without retaining the optic nerve sheath in group 2 (n=50). The effects of the design of the surgical methods on the post-surgical outcome are: One patient (1/36, 2.8%) had recurrence in Group 1 and one patient (1/50, 2.0%) had recurrence in group 2. The differences in the surgical outcomes of the two groups regarding exophthalmos, conjunctiva swelling, eye movement disorder, and ptosis were found to be statistically significant (P<0.05). Compared with group 2, the surgical outcomes in the postoperative phase of Group 1 were more satisfactory.

CONCLUSIONS

The two surgical methods do not increase the recurrence rate of tumors. The resection of OPGs through an optic nerve sheath incision was found to be an ideal surgical method for reducing complications in the postoperative phase and for providing better surgical outcomes.

Temporal, spatial, and genetic constraints contribute to the patterning and penetrance of murine neurofibromatosis-1 optic glioma

BACKGROUND

Brain tumors are the most common solid tumors of childhood, but little is understood about the factors that influence their development. Pediatric low-grade gliomas in particular display unique temporal and spatial localization associated with different genetic mutations (eg, BRAF genomic alterations, mutations in the neurofibromatosis type 1 [NF1] gene) for reasons that remain unclear. NF1 low-grade gliomas typically arise in the optic pathway of young children as optic pathway gliomas (OPGs), likely from a cell of origin that resides within the third ventricular zone (TVZ). However, the factors that contribute to their distinct temporal patterning and penetrance have not been adequately explored.

METHODS

TVZ neuroglial progenitor cells (NPCs) were analyzed over the course of mouse brain development. Progenitors isolated by fluorescence-activated cell sorting (FACS) were assessed for functional and molecular differences. The impact of different germline Nf1 mutations on TVZ NPC properties was analyzed using genetically engineered mice.

RESULTS

We identify 3 individual factors that could each contribute to Nf1 optic glioma temporal patterning and penetrance. First, there are 3 functionally and molecularly distinct populations of mouse TVZ NPCs, one of which ("M" cells) exhibits the highest clonogenic incidence, proliferation, and abundance during embryogenesis. Second, TVZ NPC proliferation dramatically decreases after birth. Third, germline Nf1 mutations differentially increase TVZ NPC proliferation during embryogenesis.

CONCLUSIONS

The unique temporal patterning and penetrance of Nf1 optic glioma reflects the combined effects of TVZ NPC population composition, time-dependent changes in progenitor proliferation, and the differential impact of the germline Nf1 mutation on TVZ NPC expansion.

NF1 optic pathway glioma: analyzing risk factors for visual outcome and indications to treat

BACKGROUND

The aim of the project was to identify risk factors associated with visual progression and treatment indications in pediatric patients with neurofibromatosis type 1 associated optic pathway glioma (NF1-OPG).

METHODS

A multidisciplinary expert group consisting of ophthalmologists, pediatric neuro-oncologists, neurofibromatosis specialists, and neuro-radiologists involved in therapy trials assembled a cohort of children with NF1-OPG from 6 European countries with complete clinical, imaging, and visual outcome datasets. Using methods developed during a consensus workshop, visual and imaging data were reviewed by the expert team and analyzed to identify associations between factors at diagnosis with visual and imaging outcomes.

RESULTS

Eighty-three patients (37 males, 46 females, mean age 5.1 ± 2.6 y; 1-13.1 y) registered in the European treatment trial SIOP LGG-2004 (recruited 2004-2012) were included. They were either observed or treated (at diagnosis/after follow-up).In multivariable analysis, factors present at diagnosis associated with adverse visual outcomes included: multiple visual signs and symptoms (adjusted odds ratio [adjOR]: 8.33; 95% CI: 1.9-36.45), abnormal visual behavior (adjOR: 4.15; 95% CI: 1.20-14.34), new onset of visual symptoms (adjOR: 4.04; 95% CI: 1.26-12.95), and optic atrophy (adjOR: 3.73; 95% CI: 1.13-12.53). Squint, posterior visual pathway tumor involvement, and bilateral pathway tumor involvement showed borderline significance. Treatment appeared to reduce tumor size but improved vision in only 10/45 treated patients. Children with visual deterioration after primary observation are more likely to improve with treatment than children treated at diagnosis.

CONCLUSIONS

The analysis identified the importance of symptomatology, optic atrophy, and history of vision loss as predictive factors for poor visual outcomes in children with NF1-OPG.

Case Report: Chemotherapy Indication in a Case of Neurofibromatosis Type 1 Presenting Optic Pathway Glioma: A One-Year Clinical Case Study Using Differential Tractography Approach

Neurofibromatosis type 1 (NF1) is associated with peripheral and central nervous system tumors. It is noteworthy that the regions in which these tumors frequently arise are the optic pathways (OPs) and the brainstem. Thus, we decided to trace the procedure of diffusion Magnetic Resonance Imaging (dMRI) alterations along with Short-Wavelength Automated Perimetry (SWAP) examinations of the OPs after surgery and chemotherapy over 1 year, which enabled us to evaluate chemotherapy's efficacy in an NF1 patient with an OP tumor. In this study, a 25-year-old woman with NF1 and left optic radiation (OR) glioma underwent surgery to remove the glioma. Immunohistochemistry (IHC) revealed a Pilocytic Astrocytoma (PA) WHO grade I. Post-operation chemotherapy done using nine treatment cycles of administering Temozolomide (TMZ) for 5 days every 4 weeks. Applying the region of interest (ROI) differential tractography method and SWAP four times every 3 months allowed us to follow the patient's visual acuity alterations longitudinally. The differential deterministic tractography method and statistical analyses enabled us to discover the white matter (WM) tracts anisotropy alterations over time. Furthermore, statistical analyses on the SWAP results along time illustrated possible alterations in visual acuity. Then, we could compare and associate the findings with the SWAP examinations and patient symptoms longitudinally. Statistical analyses of SWAP tests revealed a significant improvement in visual fields, and longitudinal differential tractography showed myelination and dense axonal packing in the left OR after 1 year of treatment. In this study, we examined an old hypothesis suggesting that chemotherapy is more effective than radiotherapy for NF1 patients with OP gliomas (OPGs) because of the radiation side effects on the visual field, cognition, and cerebrovascular complications. Our longitudinal clinical case study involving dMRI and SWAP on a single NF1-OPG patient showed that chemotherapy did not suppress the OP myelination over time. However, it should be noted that this is a clinical case study, and, therefore, the generalization of results is limited. Future investigations might focus on genetic-based imaging, particularly in more cases. Further, meta-analyses are recommended for giving a proper Field Of View (FOV) to researchers as a subtle clue regarding precision medicine.

Update on Circumscribed Gliomas and Glioneuronal Tumors

Well-circumscribed intra-axial CNS tumors encompass a wide variety of gliomas and glioneuronal tumors, usually corresponding to WHO grades I and II. Nonetheless, sometimes high-grade 'diffuse' gliomas such as gliosarcoma and giant cell glioblastoma can be relatively circumscribed but are often found to have foci of diffuse infiltration on careful examination, harboring distinct molecular alterations. These tumors are excluded from the discussion in this chapter with the current review emphasizing on lower-grade entities to include a brief description of their histology and associated molecular findings. Like elsewhere in brain biopsy evaluation, imaging is crucial and acts as a surrogate to gross examination. Given the circumscribed nature of these tumors, surgery alone is the mainstay treatment in most entities.

Comparison of Cancer Prevalence in Patients With Neurofibromatosis Type 1 at an Academic Cancer Center vs in the General Population From 1985 to 2020

IMPORTANCE

Neurofibromatosis type 1 (NF1) is a complex genetic disorder that is associated with not only neurofibromas, but also an increased susceptibility to other neoplasms.

OBJECTIVE

To evaluate the prevalence of neoplasia and outcomes among patients with NF1.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted among patients with NF1 at a single academic cancer center from 1985 to 2020 with median (range) follow-up of 2.9 years (36 days to 30.5 years). Of 2427 patients evaluated for NF1, 1607 patients who met the National Institutes of Health consensus criteria for NF1 were included. This group was compared with estimates from Surveillance, Epidemiology, and End Results (SEER) Cancer Statistics Review 1975 to 2015 and SEER participants database unless otherwise specified. Data were analyzed from August 2018 to March 2020.

MAIN OUTCOMES AND MEASURES

Disease-specific survival (DSS) was measured from diagnosis date to date of neoplasm-specific death or censorship and calculated using the Kaplan-Meier method. Survival curves were compared using the log-rank test. Deaths from disease were considered a DSS end point; other deaths were considered censored observations. Secondary outcome measures were comparisons of (1) overall survival of patients with NF1 with neurofibroma neoplasms vs those without nonneurofibroma neoplasms, (2) neoplasm prevalence in the NF1 group vs general population estimates, and (3) age at diagnosis in the NF1 group vs general population estimates for the most common neoplasms in the NF1 group.

RESULTS

Among 1607 patients with NF1, the median (range) age at initial visit was 19 years (1 month to 83 years) and 840 (52.3%) were female patients. Among 666 patients who developed other neoplasms in addition to neurofibromas (41.4%), 295 patients (18.4%) developed glioma and 243 patients (15.1%) developed malignant peripheral nerve sheath tumor (MPNST), the most common neoplasms. Patients with NF1, compared with the general population, developed several neoplasms at a younger mean (SD) age (low-grade glioma: 12.98 [11.09] years vs 37.76 [24.53] years; P < .0001; high-grade glioma [HGG]: 27.31 [15.59] years vs 58.42 [19.09] years; P < .0001; MPNST: 33.88 [14.80] years vs 47.06 [20.76] years; P < .0001; breast cancer: 46.61 [9.94] years vs 61.71 [13.85] years; P < .0001). Patients with NF1 developed neoplasms more frequently compared with the general population (odds ratio, 9.5; 95% CI, 8.5-10.5; P < .0001). Among patients with NF1, significantly lower 5-year DSS rates were found among those with undifferentiated pleomorphic sarcoma (1 of 5 patients [20.0%]), HGG (8 of 34 patients [23.1%]), MPNST (72 of 228 patients [31.6%]), ovarian carcinoma (4 of 7 patients [57.1%]), and melanoma (8 of 12 patients [66.7%]) compared with those who had neoplasms classified as other (110 of 119 patients [92.4%]) (all P < .001) .

CONCLUSIONS AND RELEVANCE

This cohort study found that among patients with NF1, those who developed undifferentiated pleomorphic sarcoma, HGG, MPNST, ovarian carcinoma, or melanoma had significantly lower DSS rates compared with those who developed other neoplasms. This study also found that patients with NF1 developed some neoplasms more frequently and at a younger age compared with individuals without NF1. HGGs and MPNST were noteworthy causes of death among patients NF1. This information may be useful for NF1 patient counseling and follow-up.

Cutaneous Findings in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a complex autosomal dominant disorder associated with germline mutations in the NF1 tumor suppressor gene. NF1 belongs to a class of congenital anomaly syndromes called RASopathies, a group of rare genetic conditions caused by mutations in the Ras/mitogen-activated protein kinase pathway. Generally, NF1 patients present with dermatologic manifestations. In this review the main features of café-au-lait macules, freckling, neurofibromas, juvenile xanthogranuloma, nevus anemicus and other cutaneous findings will be discussed.

MRI-based diagnosis and treatment of pediatric brain tumors: is tissue sample always needed?

Traditional management of newly diagnosed pediatric brain tumors (PBTs) consists of cranial imaging, typically magnetic resonance imaging (MRI), and is frequently followed by tissue diagnosis, through either surgical biopsy or tumor resection. Therapy regimes are typically dependent on histological diagnosis. To date, many treatment regimens are based on molecular biology. The scope of this article is to discuss the role of diagnosis and further treatment of PBTs based solely on MRI features, in light of the latest treatment protocols. Typical MRI findings and indications for surgical biopsy of these lesions are described.

Neurofibromatosis Type 1-Associated Optic Pathway Glioma in Children: A Follow-Up of 10 Years or More

PURPOSE

This study reports on neurofibromatosis type 1 (NF1)-associated optic pathway gliomas (OPGs) and a follow-up period of at least 10 years in a cohort of children. OPGs are a common manifestation of NF1 and can cause significant visual morbidity. Long-term follow-up in children with NF1-associated OPGs has not been reported previously.

DESIGN

Retrospective observational case series.

METHODS

This study included children with a documented follow-up of at least 10 years. Three final outcomes were evaluated: visual acuity (VA) per eye (i.e., in the more severely affected eye), VA per patient (i.e., VA when both eyes were open), and the presence of optic nerve head pallor.

RESULTS

A total of 45 children were included, followed for a mean of 14 years (range, 10-21 years). At the end of follow-up, abnormal VA (considered moderate to severe impairment) in the more severely affected eye was present in 36% of the patients and in both eyes in 11%. Optic nerve head pallor of 1 or both nerves was present in 62%. In multivariate analysis, only initial VA and optic nerve head appearance at presentation were found to predict the final outcomes. All patients, except for 1, were asymptomatic at presentation and had normal VA and nerves that appeared normal, preserved their good vision in both eyes. Only 1 patient, who had normal VA and normal appearing nerves at presentation, had moderate to severe VA loss at long term follow-up.

CONCLUSIONS

In this study, children with NF1-associated OPG whose examination signs and symptoms were normal had a normal initial examination and excellent long-term visual and anatomical outcomes. VA and the appearance of the optic nerve head at presentation predict long-term outcome.

Management of Children with Optic Gliomas and Neurofibromatosis Type 1

Optic pathway gliomas (OPG) are a common cancer in children with neurofibromatosis type 1. OPGs can cause clinical symptoms such as reduction of visual acuity, alterations of the visual field, pallor of the optical papilla, strabismus, endocrinological alterations up to diencephalic syndrome.The current guidelines provide for wait and see as the main approach if the tumor is not causing visual deterioration and adopting treatment only in the event of significant impairment of the visual function. Therefore, it is essential to early detect the visual deterioration changes as well as the identification of children eligible for treatment.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

Quantitative MRI demonstrates abnormalities of the third ventricle subventricular zone in neurofibromatosis type-1 and sporadic paediatric optic pathway glioma

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MRI provides supporting evidence of third ventricle subventricular involvement in OPG.

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Third ventricle subventricular zone ADC and CBF differs between NF1 and sporadic OPG.

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Third ventricle subventricular zone ADC correlates with vision in sporadic OPG.

Background

The subventricular zone of the third ventricle (TVZ) is a germinal stem cell niche, identified as the possible location of optic pathway glioma (OPG) cell origin. Paediatric OPGs are predominantly diagnosed as low-grade astrocytomas, which are either sporadic or are associated with neurofibromatosis type-1 (NF1). These tumours often cause a significant impairment to visual acuity (VA). Infiltrative/invasive tumour activity is associated with increased apparent diffusion coefficient (ADC) and cerebral blood flow (CBF). This study aimed to determine whether TVZ imaging features differed between sporadic-OPG, NF1-OPG and controls, and whether the ADC and CBF profile at the germinal stem cell niche (the TVZ) correlated with the primary outcome of VA.

Methods

ADC and CBF MRI data were acquired from 30 paediatric OPG patients (median age 6 years; range 8 months–17 years), along with VA measurements, during clinical surveillance of their tumour. Values for mean ADC and maximum CBF were measured at the TVZ, and normalized to normal-appearing grey matter. These values were compared between the two OPG groups and the healthy control subjects, and multivariate linear regression was used to test the linear association between these values and patient’s VA.

Results

In the TVZ, normalized mean ADC was higher in NF1-associated OPG patients (N = 15), compared to both sporadic OPG patients (N = 15; p = 0.010) and healthy controls (N = 14; p < 0.001). In the same region, normalized maximum CBF was higher in sporadic OPG patients compared to both NF1-OPG patients (p = 0.016) and healthy controls (p < 0.001). In sporadic OPG patients only, normalized mean ADC in the TVZ was significantly correlated with visual acuity (R² = 0.41, p = 0.019). No significant correlations were found between TVZ CBF and ADC values and visual acuity in the NF1-associated OPG patients.

Conclusion

Quantitative MRI detects TVZ abnormalities in both sporadic and NF1-OPG patients, and identifies TVZ features that differentiate the two. TVZ features may be useful MRI markers of interest in future predictive studies involving sporadic OPG.

Visual function tests including the role of optical coherence tomography in neurofibromatosis 1

Optic pathway glioma (OPG) is a common and significant complication of neurofibromatosis 1 (NF-1) that might lead to vision loss. The main reason to treat OPG is to preserve vision. Tumor location along the visual pathway largely dictates the presenting signs and symptoms. Clinical ophthalmic evaluation is focused on optic nerve functions including evaluation of pupils' reaction to light, visual acuity, color vision, and visual field, as well as optic nerve appearance. An important relatively new ancillary test is optic coherence tomography (OCT) that measures the volume of retinal nerve fiber layer around the optic nerve and the ganglion cell layer-inner plexiform layer (GCL-IPL) of the macula, both proved to be strongly associated with losing vision in OPG. Accurate evaluation of vision functions plays a critical role in the decision of treatment. In this review, we describe the ophthalmological assessment including new biomarkers in clinical use. We also outline prognostic factors and current recommendations for surveillance and indications for treatment.

Neurofibromatosis 1-associated optic pathway gliomas

BACKGROUND

Optic Pathway Gliomas (OPG) are the most common brain tumor in Neurofibromatosis 1 patients (NF1). They are found along the optic pathway and may involve the optic nerves, chiasm, retro-chiasmatic structures, and the optic radiations. NF1 associate OPG (NF1-OPG) have variable presentation, disease course and response to treatment. The optimal management is patient-specific and should be tailored by a multidisciplinary team. Age, sex, histology, and molecular markers may be important factors in the individualized decision-making process. Chemotherapy is the first-line treatment in cases of progressive tumors, and visual preservation is the main goal of treatment.

PURPOSE

In this paper we will review the disease, practical management, and recent advances of NF1-OPG.

A rare case of neurofibromatosis type I with unilateral congenital ectropion uveae and glaucoma

Purpose

Neurofibromatosis Type I (NF-1) is a neurocutaneous disease affecting the skin, eye and peripheral nervous system. Congenital glaucoma is a rare association, but can be a prelude to the diagnosis of NF-1 later in life. We report this unusual association in a child and discuss the possible underlying pathophysiologic mechanisms.

Observations

A nine year old female child on treatment for glaucoma in the right eye was referred to us for definitive management. Her ocular evaluation was remarkable for reduced visual acuity, megalocornea with buphthalmos, congenital ectropionuveae, Lisch nodules and glaucomatous optic neuropathy in the right eye. Systemic evaluation revealed café-au-lait spots on the chest and back. A diagnosis of Neurofibromatosis Type I with congenital ectropion uveae and glaucoma was arrived at and neuroimaging failed to detect any optic pathway gliomas. In view of advanced glaucomatous neuropathy, a conservative therapy was recommended.

Conclusionand importance

Unilateral congenital glaucomas with ectropion uveae are likely to be associated with NF-1. These children should be monitored closely for glaucoma progression and may require neurological evaluation including imaging studies to exclude optic pathway gliomas.

A systematic review of ongoing clinical trials in optic pathway gliomas

INTRODUCTION

Optic pathway gliomas (OPGs), also known as Visual Pathway Gliomas, are insidious, debilitating tumours. They are most commonly WHO grade 1 pilocytic astrocytomas and frequently occur in patients with neurofibromatosis type 1. The location of OPGs within the optic pathway typically precludes complete resection or optimal radiation dosing, hence outcomes remain poor compared to many other low-grade gliomas. The aim of this systematic review was to formulate a comprehensive list of all current ongoing clinical trials that are specifically looking at clinical care of OPGs in order to identify trends in current research and provide an overview to guide future research efforts.

METHODS

This systematic review was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The Cochrane Controlled Register of Trials (CENTRAL) and ClinicalTrials.gov were searched. Inclusion and exclusion criteria were applied and final results were reviewed.

RESULTS

501 clinical trials were identified with the search strategy. All were screened and eligible studies extracted and reviewed. This yielded 36 ongoing clinical trials, 27 of which were pharmacological agents in phase I-III. The remaining trials were a mixture of biological agents, radiation optimisation, diagnostic imaging, surgical intervention, and a social function analysis.

CONCLUSION

OPG is a complex multifaceted disease, and advances in care require ongoing research efforts across a spectrum of different research fields. This review provides an update on the current state of research in OPG and summarises ongoing trials.

Management of incidental brain tumors in children: a systematic review

BACKGROUND

Due to technical advancements and availability of neuroimaging, detection of incidental pediatric brain tumors (IPBT) is growing rapidly. The management of these asymptomatic lesions remains unclear; radiological, pathological, and clinical risk factors for further growth and malignant transformation (MT) are not well defined.

METHODS

We systematically reviewed the literature on the dilemmas and management of IPBT suggestive of a low-grade brain tumor (LGBT). Keyword searches of the PubMed and Medline (NCBI) databases identified studies on IPBT describing the prevalence, neuroimaging, management, or risk of MT through July 2019. References of the identified articles were also reviewed.

RESULTS

A total of 2021 records were screened. Fifty-nine full-text articles were reviewed, and 34 published studies were included. IPBT are diagnosed in 0.2-5.7% of children undergoing brain imaging for various reasons. The accepted approach for management of lesions showing radiological characteristics suggestive of LGBT is radiological follow-up. The rate at which additional intervention is required during follow-up for these apparently low-grade lesions is 9.5%. Nevertheless, the dilemma of early surgical resection or biopsy vs. clinical and radiological follow-up of IPBT is still unresolved. The risk in these cases is missing a transformation to a higher grade tumor. However, MT of pediatric LGBT is very rare, occurring in less than 3% of the cases of proven low-grade gliomas in children. The risk of future MT in pediatric low-grade gliomas seems to be greater in the presence of specific molecular markers such as BRAF V-600E, CDKN2A, and H3F3A K27M.

CONCLUSIONS

The natural history, management, and prognosis of IPBT remain ambiguous. It seems that lesions suggestive of LGBT can initially be followed, since many of these lesions remain stable over time and MT is rare. However, controversy among centers concerning the ideal approach still exists. Further observational and prospective cohort studies, focusing on potential clinical and radiological characteristics or risk factors suggestive of high-grade tumors, tumor progress, or MT of IPBT, are needed.

Predicting pediatric optic pathway glioma progression using advanced magnetic resonance image analysis and machine learning

BACKGROUND

Optic pathway gliomas (OPGs) are low-grade tumors of the white matter of the visual system with a highly variable clinical course. The aim of the study was to generate a magnetic resonance imaging (MRI)-based predictive model of OPG tumor progression using advanced image analysis and machine learning techniques.

METHODS

We performed a retrospective case-control study of OPG patients managed between 2009 and 2015 at an academic children's hospital. Progression was defined as radiographic tumor growth or vision decline. To generate the model, optic nerves were manually highlighted and optic radiations (ORs) were segmented using diffusion tractography tools. For each patient, intensity distributions were obtained from within the segmented regions on all imaging sequences, including derivatives of diffusion tensor imaging (DTI). A machine learning algorithm determined the combination of features most predictive of progression.

RESULTS

Nineteen OPG patients with progression were matched to 19 OPG patients without progression. The mean time between most recent follow-up and most recently analyzed MRI was 3.5 ± 1.7 years. Eighty-three MRI studies and 532 extracted features were included. The predictive model achieved an accuracy of 86%, sensitivity of 89%, and specificity of 81%. Fractional anisotropy of the ORs was among the most predictive features (area under the curve 0.83, P < 0.05).

CONCLUSIONS

Our findings show that image analysis and machine learning can be applied to OPGs to generate a MRI-based predictive model with high accuracy. As OPGs grow along the visual pathway, the most predictive features relate to white matter changes as detected by DTI, especially within ORs.

Congenital abnormalities of the retinal vasculature in neurofibromatosis type I

The aim of this cross-sectional study was to investigate congenital abnormalities of the retinal vasculature (CARVs) in patients with neurofibromatosis type I (NF-1). Forty-eight patients (96 eyes) with NF-1 diagnosed according to the National Institutes of Health (NIH) criteria and 48 healthy controls were included in this study. Standard fundus photographs were obtained for each subject to evaluate the presence and frequency of CARVs. The sensitivity, specificity, and diagnostic accuracy of different cut-off numbers of CARVs were compared with those of the NIH criteria. Forty-four (91.7%) patients in the NF-1 group demonstrated either supranumeraty optic disc vessels or triple branching of the retinal vasculature, and 22 patients (45.8%) demonstrated both findings. The frequencies of these two CARVs were significantly different between the two groups (p < 0.00001). A cut-off value of either one for supranumerary optic disc vessels or triple branching showed the highest accuracy along with sensitivity and specificity of 91.7% and 87.5%. CARVs such as supranumerary optic disc vessels or triple branching were frequently observed in NF-1 patients, and their occurrence was unrelated to the age of patients. Thus, these CARVs could be added as new ophthalmologic manifestions for NF-1 and may potentially enable early diagnosis of NF-1.

Advanced pharmacological therapies for neurofibromatosis type 1-related tumors

Neurofibromatosis Type 1 (NF1) is an autosomal dominant tumor-predisposition disorder that is caused by a heterozygous loss of function variant in the NF1 gene, which encodes a protein called neurofibromin. The absence of neurofibromin causes increased activity in the Rat sarcoma protein (RAS) signalling pathway, which results in an increased growth and cell proliferation. As a result, both oncological and non-oncological comorbidities contribute to a high morbidity and mortality in these patients. Optic pathways gliomas, plexiform neurofibromas and malignant peripheral nerve sheath tumor (MPNST) are the most frequent NF1-associated tumors. The treatment of these complications is often challenging, since surgery may not be feasible due to the location, size, and infiltrative nature of these tumors, and standard chemotherapy or radiotherapy are burdened by significant toxicity and risk for secondary malignancies. For these reasons, following the novel discoveries of the pathophysiological mechanisms that lead to cell proliferation and tumorigenesis in NF1 patients, emerging drugs targeting specific signalling pathways (i.e. the MEK/ERK cascade), have been developed with promising results.

Germline genetic landscape of pediatric central nervous system tumors

Central nervous system (CNS) tumors are the second most common type of cancer among children. Depending on histopathology, anatomic location, and genomic factors, specific subgroups of brain tumors have some of the highest cancer-related mortality rates or result in considerable lifelong morbidity. Pediatric CNS tumors often occur in patients with genetic predisposition, at times revealing underlying cancer predisposition syndromes. Advances in next-generation sequencing (NGS) have resulted in the identification of an increasing number of cancer predisposition genes. In this review, the literature on genetic predisposition to pediatric CNS tumors is evaluated with a discussion of potential future targets for NGS and clinical implications. Furthermore, we explore potential strategies for enhancing the understanding of genetic predisposition of pediatric CNS tumors, including evaluation of non-European populations, pan-genomic approaches, and large collaborative studies.

Effect of age and neurofibromatosis type 1 status on white matter integrity in the optic radiations

Background

Adults with neurofibromatosis type 1 (NF1) have decreased white matter integrity, but differences in children with NF1 have not been described. Defining normal values for diffusion tensor imaging (DTI) measures, especially in the optic radiations, is important to the development of DTI as a potential biomarker of visual acuity in children with optic pathway glioma. This study examines the effect of age and NF1 status on DTI measures in children.

Methods

In this retrospective study, MR imaging including DTI was conducted in 93 children (40 children with NF1 and 53 healthy controls) between 0 and 14 years of age. Regression models of age, sex, and NF1 status on DTI measures were evaluated, and tract-based spatial statistics (TBSS) compared DTI measures in age-matched NF1 to non-NF1 cohorts.

Results

Fractional anisotropy, radial diffusivity, and mean diffusivity in white matter tracts of the optic radiations varied with age and were best modeled by a logarithmic function. Age-related DTI measure change was different in NF1 versus non-NF1 subjects. Normal values and 95% confidence intervals for age 0.5–12 years were derived for both groups. Differences in DTI measures between NF1 and non-NF1 groups at a range of ages were shown diffusely throughout the cerebral white matter using TBSS.

Conclusions

Children with NF1 demonstrate increased diffusion throughout the brain compared to children without NF1 suggesting a potentially altered developmental trajectory of optic radiation microstructure. Defining normal values for white matter integrity in children with NF1 may help target early intervention efforts in this vulnerable group.

Germline cancer predisposition variants and pediatric glioma: a population-based study in California

BACKGROUND

Pediatric astrocytoma constitutes a majority of malignant pediatric brain tumors. Previous studies that investigated pediatric cancer predisposition have primarily been conducted in tertiary referral centers and focused on cancer predisposition genes. In this study, we investigated the contribution of rare germline variants to risk of malignant pediatric astrocytoma on a population level.

METHODS

DNA samples were extracted from neonatal dried bloodspots from 280 pediatric astrocytoma patients (predominantly high grade) born and diagnosed in California and were subjected to whole-exome sequencing. Sequencing data were analyzed using agnostic exome-wide gene-burden testing and variant identification for putatively pathogenic variants in 175 a priori candidate cancer-predisposition genes.

RESULTS

We identified 33 putatively pathogenic germline variants among 31 patients (11.1%) which were located in 24 genes largely involved in DNA repair and cell cycle control. Patients with pediatric glioblastoma were most likely to harbor putatively pathogenic germline variants (14.3%, N = 9/63). Five variants were located in tumor protein 53 (TP53), of which 4 were identified among patients with glioblastoma (6.3%, N = 4/63). The next most frequently mutated gene was neurofibromatosis 1 (NF1), in which putatively pathogenic variants were identified in 4 patients with astrocytoma not otherwise specified. Gene-burden testing also revealed that putatively pathogenic variants in TP53 were significantly associated with pediatric glioblastoma on an exome-wide level (odds ratio, 32.8, P = 8.04 × 10-7).

CONCLUSION

A considerable fraction of pediatric glioma patients, especially those of higher grade, harbor a putatively pathogenic variant in a cancer predisposition gene. Some of these variants may be clinically actionable or may warrant genetic counseling.

Pretreatment Endocrine Disorders Due to Optic Pathway Gliomas in Pediatric Neurofibromatosis Type 1: Multicenter Study

CONTEXT

Up to 20% of children with neurofibromatosis type 1 (NF1) develop low-grade optic pathway gliomas (OPGs) that can result in endocrine dysfunction. Data on prevalence and type of endocrine disorders in NF1-related OPGs are scarce.

OBJECTIVES

The aim of the study was to determine the prevalence of endocrine dysfunctions in patients with NF1 and OPGs and to investigate predictive factors before oncological treatment.

DESIGN

Multicenter retrospective study.

SETTINGS AND PATIENTS

Records were reviewed for 116 children (64 females, 52 males) with NF1 and OPGs followed at 4 Italian centers.

MAIN OUTCOME MEASURES

We evaluated endocrine function and reviewed brain imaging at the time of OPG diagnosis before radio- and chemotherapy and/or surgery. OPGs were classified according to the modified Dodge classification.

RESULTS

Thirty-two children (27.6%) with a median age of 7.8 years had endocrine dysfunctions including central precocious puberty in 23 (71.9%), growth hormone deficiency in 3 (9.4%), diencephalic syndrome in 4 (12.5%), and growth hormone hypersecretion in 2 (6.2%). In a multivariate cox regression analysis, hypothalamic involvement was the only independent predictor of endocrine dysfunctions (hazard ratio 5.02 [1.802-13.983]; P = .002).

CONCLUSIONS

Endocrine disorders were found in approximately one-third of patients with Neurofibromatosis type 1 and OPGs before any oncological treatment, central precocious puberty being the most prevalent. Sign of diencephalic syndrome and growth hormone hypersecretion, although rare, could be predictive of optic pathway gliomas in NF1. Tumor location was the most important predictor of endocrine disorders, particularly hypothalamic involvement.

Nonoptic pathway tumors in children with neurofibromatosis type 1

OBJECTIVE

To define the radiologic features and natural history of nonoptic pathway tumors (non-OPTs) in children with neurofibromatosis type 1 (NF1).

METHODS

We performed a retrospective cross-sectional analysis of 64 children with NF1 harboring 100 probable non-OPTs. Age at diagnosis, sex, tumor location, number of tumors, symptomology, concurrent OPT, radiographic progression (defined as qualitative and quantitative increases in size), and treatment were assessed. Tumor volumes were measured from initial presentation until treatment or end of disease progression.

RESULTS

Sixty-three percent of probable non-OPTs progressed over time, where radiographic progression was concomitantly associated with clinical progression. Fifty-two percent of patients had incidentally identified probable non-OPTs. Twenty-five percent of patients were symptomatic at initial diagnosis, all of whom harbored tumors that grew on subsequent scans and required tumor-directed therapy. There were no clinical differences between probable non-OPTs localized to the brainstem vs other locations with respect to age, sex, concurrent optic pathway glioma, symptomology, and treatment. The average time from diagnosis to stabilization or decrease in tumor size was 2.34 years (SD, 2.15 years). Nineteen biopsied lesions were all histopathologically confirmed as tumor. Six children (9%) had deep extensive tumors, who presented earlier (mean age at diagnosis, 3.88 years), required multiple treatments, and had a shorter mean progression-free survival (48 months).

CONCLUSIONS

Over half of children with NF1 in this study developed probable non-OPTs, the majority of which were clinically and radiographically progressive. While brainstem and nonbrainstem gliomas share similar clinical features and natural history, deep extensive tumors comprise a distinct aggressive group of tumors that warrant close attention.

An update on the central nervous system manifestations of neurofibromatosis type 1

Neurofibromatosis 1 (NF1) is an autosomal dominant genetic disorder that presents with variable phenotypes as a result of mutations in the neurofibromatosis type 1 (NF1) gene and subsequently, abnormal function of the protein product, neurofibromin. Patients with NF1 are at increased risk for central nervous system (CNS) manifestations including structural, functional, and neoplastic disease. The mechanisms underlying the varied manifestations of NF1 are incompletely understood, but the loss of functional neurofibromin, resulting in sustained activation of the oncoprotein RAS, is responsible for tumorigenesis throughout the body, including the CNS. Much of our understanding of NF1-related CNS manifestations is from a combination of data from animal models and natural history studies of people with NF1 and CNS disease. Data from animal models suggest the importance of both Nf1 mutations and somatic genetic alterations, such as Tp53 loss, for development of neoplasms, as well as the role of the timing of the acquisition of such alterations on the variability of CNS manifestations. A variety of non-neoplastic structural (macrocephaly, hydrocephalus, aqueductal stenosis, and vasculopathy) and functional (epilepsy, impaired cognition, attention deficits, and autism spectrum disorder) abnormalities occur with variable frequency in individuals with NF1. In addition, there is increasing evidence that similar appearing CNS neoplasms in people with and without the NF1 syndrome are due to distinct oncogenic pathways. Gliomas in people with NF1 show alterations in the RAS/MAPK pathway, generally in the absence of BRAF alterations (common to sporadic pilocytic astrocytomas) or IDH or histone H3 mutations (common to diffuse gliomas subsets). A subset of low-grade astrocytomas in these patients remain difficult to classify using standard criteria, and occasionally demonstrate morphologic features resembling subependymal giant cell astrocytomas that afflict patients with tuberous sclerosis complex ("SEGA-like astrocytomas"). There is also emerging evidence that NF1-associated high-grade astrocytomas have frequent co-existing alterations such as ATRX mutations and an alternative lengthening of telomeres (ALT) phenotype responsible for unique biologic properties. Ongoing efforts are seeking to improve diagnostic accuracy for CNS neoplasms in the setting of NF1 versus sporadic tumors. In addition, MEK inhibitors, which act on the RAS/MAPK pathway, continue to be studied as rational targets for the treatment of NF1-associated tumors, including CNS tumors.

Pediatric low-grade glioma in the era of molecular diagnostics

Low grade gliomas are the most frequent brain tumors in children and encompass a spectrum of histologic entities which are currently assigned World Health Organisation grades I and II. They differ substantially from their adult counterparts in both their underlying genetic alterations and in the infrequency with which they transform to higher grade tumors. Nonetheless, children with low grade glioma are a therapeutic challenge due to the heterogeneity in their clinical behavior – in particular, those with incomplete surgical resection often suffer repeat progressions with resultant morbidity and, in some cases, mortality. The identification of up-regulation of the RAS–mitogen-activated protein kinase (RAS/MAPK) pathway as a near universal feature of these tumors has led to the development of targeted therapeutics aimed at improving responses while mitigating patient morbidity. Here, we review how molecular information can help to further define the entities which fall under the umbrella of pediatric-type low-grade glioma. In doing so we discuss the specific molecular drivers of pediatric low grade glioma and how to effectively test for them, review the newest therapeutic agents and their utility in treating this disease, and propose a risk-based stratification system that considers both clinical and molecular parameters to aid clinicians in making treatment decisions.

Aberrantly expressed microRNAs and their implications in childhood central nervous system tumors

Even though the treatment of childhood cancer has evolved significantly in recent decades, aggressive central nervous system (CNS) tumors are still a leading cause of morbidity and mortality in this population. Consequently, the identification of molecular targets that can be incorporated into diagnostic practice, effectively predict prognosis, follow treatment response, and materialize into potential targeted therapeutic approaches are still warranted. Since the first evidence of the participation of miRNAs in cancer development and progression 20 years ago, notable progress has been made in the basic understanding of the contribution of their dysregulation as epigenetic driver of tumorigenesis. Nevertheless, among the plethora of articles in the literature, microRNA profiling of pediatric tumors are scarce. This article gives an overview of the recent advances in the diagnostic/prognostic potential of miRNAs in a selection of pediatric CNS tumors: medulloblastoma, ependymoma, pilocytic astrocytoma, glioblastoma, diffuse intrinsic pontine glioma, atypical teratoid/rhabdoid tumors, and choroid plexus tumors.

Role of visual evoked potentials and optical coherence tomography in the screening for optic pathway gliomas in patients with neurofibromatosis type I

PURPOSE

The purpose of the present study was to compare visual function assessment, visual evoked potential, and optical coherence tomography with measurement of retinal nerve fiber layer thickness for the diagnosis of optic pathway glioma in children with neurofibromatosis type 1.

METHODS

This retrospective observational study included patients with neurofibromatosis type 1 who underwent brain magnetic resonance imaging scan, visual evoked potential study, and peripapillary retinal nerve fiber layer evaluation by optical coherence tomography. Patients were tested with pattern-reversal visual evoked potential and with flash visual evoked potential in case of poor cooperation. Optical coherence tomography was performed with HRA Spectralis (Heidelberg Engineering, Heidelberg, Germany). The area under the curve of receiver operating characteristic curves was used to evaluate the accuracy of each parameter for diagnosing optic pathway glioma.

RESULTS

In all, 110 patients with neurofibromatosis type 1 were included in the study. Fifty of them had an optic pathway glioma diagnosed with magnetic resonance imaging, while 60 did not. Global retinal nerve fiber layer thickness demonstrated the highest diagnostic power for discriminating patients with and without optic pathway glioma (area under the curve = 0.758, sensitivity = 65.3%, specificity = 83.3%), followed visual acuity (area under the curve = 0.723, sensitivity = 51.1%, specificity = 91.7%) and P100 of visual evoked potential (area under the curve = 0.712, sensitivity = 69.6%, specificity = 63.8%).

CONCLUSION

The results of the present study showed that the measurement of retinal nerve fiber layer thickness was the most efficient test for discriminating patients with and without optic pathway glioma. Brain magnetic resonance imaging remains the gold standard to confirm the diagnosis of optic pathway glioma. Longitudinal studies are required to define if the early detection of tumors with optical coherence tomography could prevent vision loss and morbidity.

Phakomatoses

Phakomatoses present with characteristic findings on the skin, central or peripheral nervous system, and tumors. Neurofibromatosis type 1 is the most common syndrome and is characterized by Café-au-lait macules, intertriginous freckling, Lisch nodules, and tumors including neurofibromas, malignant peripheral nerve sheath tumors, and gliomas. Tuberous Sclerosis Complex is characterized by benign hamartomas presenting with hypomelanotic macules, shagreen patches, angiofibromas, confetti lesions and tumors including cortical tubers, subependymal nodules, subependymal giant cell astrocytomas and tumors of the kidney, lung, and heart. Managing these disorders requires disease specific supportive care, tumor monitoring, surveillance for selected cancers, and treatment of comorbid conditions.

Neurofibromatosis 1 French national guidelines based on an extensive literature review since 1966

Neurofibromatosis type 1 is a relatively common genetic disease, with a prevalence ranging between 1/3000 and 1/6000 people worldwide. The disease affects multiple systems with cutaneous, neurologic, and orthopedic as major manifestations which lead to significant morbidity or mortality. Indeed, NF1 patients are at an increased risk of malignancy and have a life expectancy about 10-15 years shorter than the general population. The mainstay of management of NF1 is a patient-centered longitudinal care with age-specific monitoring of clinical manifestations, aiming at the early recognition and symptomatic treatment of complications as they occur. Protocole national de diagnostic et de soins (PNDS) are mandatory French clinical practice guidelines for rare diseases required by the French national plan for rare diseases. Their purpose is to provide health care professionals with guidance regarding the optimal diagnostic and therapeutic management of patients affected with a rare disease; and thus, harmonizing their management nationwide. PNDS are usually developed through a critical literature review and a multidisciplinary expert consensus. The purpose of this article is to present the French guidelines on NF1, making them even more available to the international medical community. We further dwelled on the emerging new evidence that might have therapeutic potential or a strong impact on NF1 management in the coming feature. Given the complexity of the disease, the management of children and adults with NF1 entails the full complement healthcare providers and communication among the various specialties.

A nationwide, population-based study of school grades, delayed graduation, and qualification for school years 10-12, in children with brain tumors in Sweden

BACKGROUND

As many as 95.7% of children diagnosed with a brain tumor will experience persistent late effects as adults. These include difficulties with general executive functions, lower IQ, and mental fatigue, which may negatively affect school performance.

METHODS

Through the Swedish Childhood Cancer Registry, we identified 475 children born between 1988 and 1996, diagnosed with a brain tumor before their 15th birthday. School grades in "Swedish," "mathematics," and "English," if their graduation was delayed, and qualification for school years 10-12 were compared with 2197 matched controls. Furthermore, we checked for interaction effects between sex and age at diagnosis, and possible effects of tumor grade (high or low) as well as parents' education.

RESULTS

Children treated for a brain tumor performed worse in the subjects compared to controls and also had delayed graduation to a greater extent. Fewer children treated for a brain tumor than controls qualified for school years 10-12. Children treated at a young age, especially females, and children whose parents have low education seem to be at particular risk. Unexpectedly, there were no differences in outcomes between survivors with high- and low-grade tumors.

CONCLUSIONS

It is important that schools provide regular pedagogical assessment and individualized support to meet the different needs of children treated for a brain tumor. Children treated for low-grade tumors do not perform better than children treated for high-grade tumors, despite the lighter treatment, and hence require the same attention and support.

Neurotrophic Receptor Tyrosine Kinase 2 (NTRK2) Alterations in Low-Grade Gliomas: Report of a Novel Gene Fusion Partner in a Pilocytic Astrocytoma and Review of the Literature

Pilocytic astrocytoma is a low-grade glial neoplasm of the central nervous system (CNS) that tends to occur in the pediatric population and less commonly presents in adults. Hereditary pilocytic astrocytoma is often associated with germline genetic alterations in the tumor suppressor NF1, the gene responsible for the syndrome neurofibromatosis type 1. Sporadic pilocytic astrocytoma frequently harbors somatic alterations in BRAF, with rare pilocytic astrocytomas containing alterations in FGFR1 and NTRK2. NTRK2 encodes for the protein tropomyosin receptor kinase B (TrkB), which is a neurotrophin receptor with high affinity for Brain-Derived Neurotrophic Factor (BDNF), and plays a role in several physiological functions of neurons, including cell survival and differentiation. In this report, we describe a novel PML-NTRK2 gene fusion occurring in an adult sporadic pilocytic astrocytoma and review the biology and implications of specific NTRK2 mutations occurring in CNS neoplasms.

En-Bloc Resection Versus Resection After Evacuation and Suction of the Content for Orbital Optic Nerve Glioma Causing Visual Loss and Disfiguring Proptosis

PURPOSE

To evaluate the surgical outcomes of two different techniques of resection for optic nerve gliomas confined to the intra-orbital segment.

METHODS

This prospective, comparable, clinical interventional case series was conducted at the orbital clinic of Assiut University Hospital, the referral centre of Upper Egypt in the period between 2006 and 2018. The study included 10 children with optic nerve gliomas confined to the intra-orbital part without intracanalicular or intracranial extension and causing severe visual loss and disfiguring proptosis. In all cases, lateral orbitotomy was performed to expose the mass. In 5 cases (group A), the glioma was resected en-bloc. In 5 cases (group B), a new technique of resection was introduced. The wall of the glioma was incised, the content was evacuated and suctioned and followed by resection under good visualization of the markedly reduced mass in size.

RESULTS

In the 2 groups, no tumour regrowth was reported during the follow-up period of 3-12 years. In group A, the 5 cases developed postoperative third nerve damage with paralytic ptosis and one case had severe neurotrophic keratitis ended by dense corneal opacity. In group B, a healthy ipsilateral eye was preserved in all cases and no one case developed postoperative paralytic ptosis.

CONCLUSIONS

Reduction of size of an intra-orbital optic nerve glioma by evacuation and suction of the content before resection is highly recommended. This makes the surgical field during resection more visible and minimizes the possibility of third or other nerves damage.

An Update on Neurofibromatosis Type 1-Associated Gliomas

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that affects children and adults. Individuals with NF1 are at high risk for central nervous system neoplasms including gliomas. The purpose of this review is to discuss the spectrum of intracranial gliomas arising in individuals with NF1 with a focus on recent preclinical and clinical data. In this review, possible mechanisms of gliomagenesis are discussed, including the contribution of different signaling pathways and tumor microenvironment. Furthermore, we discuss the recent notable advances in the developing therapeutic landscape for NF1-associated gliomas including clinical trials and collaborative efforts.

Risk of Optic Pathway Glioma in Neurofibromatosis Type 1: No Evidence of Genotype-Phenotype Correlations in A Large Independent Cohort

The occurrence of optic pathway gliomas (OPGs) in children with neurofibromatosis type 1 (NF1) still raises many questions regarding screening and surveillance because of the lack of robust prognostic factors. Recent studies of an overall cohort of 381 patients have suggested that the genotype may be the main determinant of the development of OPG, with the risk being higher in patients harbouring NF1 mutations in the 5’ tertile and the cysteine/serine-rich domain. In an attempt to confirm this hypothesis, we used strict criteria to select a large independent cohort of 309 NF1 patients with defined constitutional NF1 mutations and appropriate brain images (255 directly enrolled and 54 as a result of a literature search). One hundred and thirty-two patients had OPG and 177 did not. The association of the position (tertiles and functional domains) and type of NF1 mutation with the development of OPG was analysed using the χ2 test and Fisher’s exact probability test; odds ratios (ORs) with 95% confidence intervals were calculated, and Bonferroni’s correction for multiple comparisons was applied; multiple logistic regression was also used to study genotype–phenotype associations further. Our findings show no significant correlation between the site/type of NF1 mutation and the risk of OPG, and thus do not support the hypothesis that certain constitutional mutations provide prognostic information in this regard. In addition, we combined our cohort with a previously described cohort of 381 patients for a total of 690 patients and statistically re-analysed the results. The re-analysis confirmed that there were no correlations between the site (tertile and domain) and the risk of OPG, thus further strengthening our conclusions.

Optic Pathway Glioma in Type 1 Neurofibromatosis: Review of Its Pathogenesis, Diagnostic Assessment, and Treatment Recommendations

Type 1 neurofibromatosis (NF1) is a dominantly inherited condition predisposing to tumor development. Optic pathway glioma (OPG) is the most frequent central nervous system tumor in children with NF1, affecting approximately 15-20% of patients. The lack of well-established prognostic markers and the wide clinical variability with respect to tumor progression and visual outcome make the clinical management of these tumors challenging, with significant differences among distinct centers. We reviewed published articles on OPG diagnostic protocol, follow-up and treatment in NF1. Cohorts of NF1 children with OPG reported in the literature and patients prospectively collected in our center were analyzed with regard to clinical data, tumor anatomical site, diagnostic workflow, treatment and outcome. In addition, we discussed the recent findings on the pathophysiology of OPG development in NF1. This review provides a comprehensive overview about the clinical management of NF1-associated OPG, focusing on the most recent advances from preclinical studies with genetically engineered models and the ongoing clinical trials.

Brain Tumors in NF1 Children: Influence on Neurocognitive and Behavioral Outcome

Neurofibromatosis type-1 (NF1) is a monogenic tumor-predisposition syndrome creating a wide variety of cognitive and behavioral abnormalities, such as decrease in cognitive functioning, deficits in visuospatial processing, attention, and social functioning. NF1 patients are at risk to develop neurofibromas and other tumors, such as optic pathway gliomas and other tumors of the central nervous system. Few studies have investigated the impact of an additional diagnosis of brain tumor on the cognitive outcome of children with NF1, showing unclear results and without controlling by the effect of surgery, radio- or chemotherapy. In the present mono-institutional study, we compared the behavioral and cognitive outcomes of 26 children with neurofibromatosis alone (NF1) with two age-matched groups of 26 children diagnosed with NF1 and untreated optic pathway glioma (NF1 + OPG) and 19 children with NF1 and untreated other central nervous system tumors (NF1 + CT). NF1 + CT and NF1 + OPG showed significantly impaired cognitive abilities compared to NF1 group, with weaknesses in visuo-spatial abilities, visual scanning and verbal working memory, while general verbal abilities are preserved. Moreover, NF1 + OPG patients present more frequent internalizing problems and increased oppositional-deviant behaviors. These results suggest that the co-diagnosis of a brain tumor in NF1 children may partially worsen the cognitive and emotional outcome.

The Diagnosis and Management of Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1), NF2, and schwannomatosis are related, but distinct, tumor suppressor syndromes characterized by a predilection for tumors in the central and peripheral nervous systems. NF1 is one of the most common autosomal dominant conditions of the nervous system. NF1 has a high degree of variability in clinical presentation, which may include multiple neoplasms as well as cutaneous, vascular, bony, and cognitive features. Some of these manifestations overlap with other genetic conditions. Accurate diagnosis of NF1 is important for individualizing clinical care and genetic counseling. This article summarizes the clinical features, diagnostic work-up, and management of NF1.

Brain tumors in Neurofibromatosis type 1

As a cancer predisposition syndrome, individuals with neurofibromatosis type 1 (NF1) are at increased risk for the development of both benign and malignant tumors. One of the most common locations for these cancers is the central nervous system, where low-grade gliomas predominate in children. During early childhood, gliomas affecting the optic pathway are most frequently encountered, whereas gliomas of the brainstem and other locations are observed in slightly older children. In contrast, the majority of gliomas arising in adults with NF1 are malignant cancers, typically glioblastoma, involving the cerebral hemispheres. Our understanding of the pathogenesis of NF1-associated gliomas has been significantly advanced through the use of genetically engineered mice, yielding new targets for therapeutic drug design and evaluation. In addition, Nf1 murine glioma models have served as instructive platforms for defining the cell of origin of these tumors, elucidating the critical role of the tumor microenvironment in determining tumor growth and vision loss, and determining how cancer risk factors (sex, germline NF1 mutation) impact on glioma formation and progression. Moreover, these preclinical models have permitted early phase analysis of promising drugs that reduce tumor growth and attenuate vision loss, as an initial step prior to translation to human clinical trials.

68Ga-NOTA-Aca-BBN(7-14) PET imaging of GRPR in children with optic pathway glioma

PURPOSE

Optic pathway glioma (OPG) is a rare neoplasm that arises predominantly during childhood. Its location in a sensitive region involving the optic pathways, onset in young patients and controversial therapy choice make the management of OPG a challenge in paediatric neuro-oncology. In this study we assessed gastrin-releasing peptide receptor (GRPR)-targeted positron emission tomography (PET) imaging in children with OPG, and the application of a PET/MRI imaging-guided surgery navigation platform.

METHODS

Eight children (five boys, mean age 8.81 years, range 5-14 years) with suspicion of optic pathway glioma on MRI were recruited. Written informed consent was obtained from all patients and legal guardians. Brain PET/CT or PET/MRI acquisitions were performed 30 min after intravenous injection of 1.85 MBq/kg body weight of ⁶⁸Ga-NOTA-Aca-BBN(7-14). Four patients also underwent ¹⁸F-FDG brain PET/CT for comparison. All patients underwent surgical resection within 1 week.

RESULTS

All 11 lesions (100%) in the eight patients showed prominent ⁶⁸Ga-NOTA-Aca-BBN(7-14) uptake with excellent contrast in relation to surrounding normal brain tissue. Tumour-to-background ratios (SUVmax and SUVmean) were significantly higher for ⁶⁸Ga-NOTA-Aca-BBN(7-14) than for ¹⁸F-FDG (28.4 ± 5.59 vs. 0.47 ± 0.11 and 18.3 ± 4.99 vs. 0.35 ± 0.07, respectively). Fusion images for tumour delineation were obtained in all patients using the PET/MRI navigation platform. All lesions were pathologically confirmed as OPGs with positive GRPR expression, and 75% were pilocytic astrocytoma WHO grade I and 25% were diffuse astrocytoma WHO grade II. There was a positive correlation between the SUV of ⁶⁸Ga-NOTA-Aca-BBN(7-14) and the expression level of GRPR (r² = 0.56, P < 0.01, for SUVmax; r² = 0.47, P < 0.05, for SUVmean).

CONCLUSION

This prospective study showed the feasibility of ⁶⁸Ga-NOTA-Aca-BBN(7-14) PET in children with OPG for tumour detection and localization. ⁶⁸Ga-NOTA-Aca-BBN(7-14) PET/MRI may be helpful for assisting surgery planning in OPG patients with severe symptoms, GRPR-targeted PET has the potential to provide imaging guidance for further GRPR-targeted therapy in patients with OPG.