Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

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.

Brain gliomas, hydrocephalus and idiopathic aqueduct stenosis in children with neurofibromatosis type 1

PURPOSE

To evaluate the incidence and clinical importance of brain gliomas - optic pathway gliomas (OPGs) and especially gliomas outside the optic pathway (GOOP) for children with neurofibromatosis type 1 (NF1), additionally, to assess the causes of obstructive hydrocephalus in NF1 children with an emphasis on cases caused by idiopathic aqueduct stenosis.

SUBJECTS AND METHODS

We analysed data from 285 NF1 children followed up on our department from 1990 to 2010 by the same examination battery.

RESULTS

We have found OPGs in 77/285 (27%) children and GOOPs in 29/285 (10,2%) of NF1 children, of who 19 had OPG and GOOP together, so the total number of brain glioma was 87/285 (30,5%). GOOPs were significantly more often treated than OPGs (p > 0.01). OPGs contain clinically important subgroup of 14/285 (4.9%) spreading to hypothalamus. Spontaneous regression was documented in 4/285 (1.4%) gliomas and the same number of NF1 children died due to gliomas. Obstructive hydrocephalus was found in 22/285 (7.7%) patients and 14/22 cases were due to glioma. Idiopathic aqueduct stenosis caused hydrocephalus in 6/22 cases and was found in 2.1% of NF1 children. Two had other cause.

CONCLUSIONS

The total brain glioma number (OPGs and only GOOPs together) better reflected the overall brain tumour risk for NF1 children. However, GOOPs occur less frequently than OPGs, they are more clinically relevant. The obstructive hydrocephalus was severe and featuring frequent complication, especially those with GOOP. Idiopathic aqueduct stenosis shows an unpredictable cause of hydrocephalus in comparison with glioma and is another reason for careful neurologic follow up.

Current treatment of optic nerve gliomas

PURPOSE OF REVIEW

Optic pathway gliomas are low-grade neoplasms that affect the precortical visual pathway of children and adolescents. They can affect the optic nerve, optic chiasm, optic tracts and radiations and can either be sporadic or associated with neurofibromatosis type one. Gliomas isolated to the optic nerve (ONG) represent a subgroup of optic pathway gliomas, and their treatment remains controversial. New developments in ONG treatment have emerged in recent years, and it is necessary for clinicians to have a current understanding of available therapies.

RECENT FINDINGS

The current review of the literature covers the background of and recent developments in ONG treatment, with a focus on standard chemotherapy, new molecularly targeted therapies, radiation therapy and surgical resection and debulking.

SUMMARY

Although standard chemotherapy remains the mainstay of ONG treatment, newer molecularly targeted therapies such as mitogen-activated protein kinase kinase inhibitors and bevacizumab represent a promising new treatment modality, and clinical studies are ongoing.

Development of a multidisciplinary clinic of neurofibromatosis type 1 and other neurocutaneous disorders in Greece. A 3-year experience

Given the complexity of neurocutaneous syndromes, a multidisciplinary approach has been advocated in order to provide optimum care. Subjects and Methods: Retrospective analysis of a cohort of 157 patients during a 3-year period, seen at a newly developed neurocutaneous clinic in a pediatric tertiary care hospital in Athens (Greece); and systematic chart review of the patients diagnosed with neurofibromatosis type 1 during this time period. Results: The most frequent neurocutaneous syndromes were neurofibromatosis type 1 (NF1) in 89 patients and tuberous sclerosis complex in 17. In 20.38% of patients a neurocutaneous syndrome was not confirmed. Approximately 2/3 of the NF1 patients underwent genetic analysis, and for 76.67% of them, a pathogenic mutation on the NF1 gene was revealed. Eighty-one patients manifested with generalized NF1 and eight with mosaic NF1. Dermatological manifestations included café-au-lait macules in all patients, followed by axillary and/or inguinal freckling (n = 57), external plexiform neurofibromas (n = 17), and cutaneous and subcutaneous neurofibromas (n = 11). Approximately half of patients had learning disabilities and attention deficit hyperactivity disorder, followed by mental retardation (n = 9), autistic spectrum disorders (n = 4), headaches (n = 3) and seizures (n = 2). Neuroimaging showed characteristic areas of hyperintensity on T2-weighted images in 74.07% of patients and optic pathway glioma in 19.75%. Two patients developed malignant peripheral sheath nerve tumor. Conclusions: Neurocutaneous syndromes are clinically heterogeneous and the surveillance of potential clinical complications is challenging. The availability of genetic diagnosis and novel imaging methods in this group of disorders is likely to further expand their clinical spectrum. Guidelines for assessment and management will need to be modified based on new available data.

Central and peripheral steady-state visual evoked potentials in children with optic pathway gliomas

PURPOSE

Treatment of optic pathway gliomas is prompted by neuroradiological evidence of tumor growth, usually associated with progressive visual loss. Despite therapy, approximately 40% will show visual deterioration. Treatment outcome is largely based on the preservation of vision. However, current visual function assessment is often unreliable in children with optic pathway gliomas who have limited collaboration. Thus, there is a need for new clinical tools to evaluate visual functions in these children. The aim of the study was to assess the value of steady-state visual evoked potentials as a tool to assess function in the central and peripheral visual fields of children with optic pathway gliomas.

METHOD

Ten patients with optic pathway gliomas and 33 healthy controls (ages 3 to 18 years) were tested using steady-state visual evoked potentials. The dartboard stimulus consisted of one central circle alternating at 16 reversals/s and one peripheral hoop alternating at 14.4 reversals/s, separated by a hoop of gray space. It was presented monocularly at 30% and 96% contrasts.

RESULTS

Results indicated that central signal-to-noise ratios were significantly lower in children with optic pathway gliomas compared to controls. However, no significant group difference was detected in the peripheral visual field.

CONCLUSION

Steady-state visual evoked potentials could eventually be implemented in the clinical assessment and follow-up of central visual field deficits in uncooperative or nonverbal children but seem to have limited usefulness for evaluation of peripheral visual field deficits. Additional studies are needed to identify testing parameters for full visual field assessment.

Astrocytoma of the optic nerve head

In this article, a clinical case of astrocytoma of optic nerve head in patient with neurofibromatosis type 1 is presented. The main feature of this clinical case is a difficulty in differential diagnosis with amelanotic choroidal melanoma.

Neurofibromin Deficiency Induces Endothelial Cell Proliferation and Retinal Neovascularization

Purpose

Neurofibromatosis type 1 (NF1) is the result of inherited mutations in the NF1 tumor suppressor gene, which encodes the protein neurofibromin. Eye manifestations are common in NF1 with recent reports describing a vascular dysplasia in the retina and choroid. Common features of NF1 retinopathy include tortuous and dilated feeder vessels that terminate in capillary tufts, increased endothelial permeability, and neovascularization. Given the retinal vascular phenotype observed in persons with NF1, we hypothesize that preserving neurofibromin may be a novel strategy to control pathologic retinal neovascularization.

Methods

Nf1 expression in human endothelial cells (EC) was reduced using small hairpin (sh) RNA and EC proliferation, migration, and capacity to form vessel-like networks were assessed in response to VEGF and hypoxia. Wild-type (WT), Nf1 heterozygous (Nf1^+/−), and Nf1^flox/+;Tie2cre pups were subjected to hyperoxia/hypoxia using the oxygen-induced retinopathy model. Retinas were analyzed quantitatively for extent of retinal vessel dropout, neovascularization, and capillary branching.

Results

Neurofibromin expression was suppressed in response to VEGF, which corresponded with activation of Mek-Erk and PI3-K-Akt signaling. Neurofibromin-deficient EC exhibited enhanced proliferation and network formation in response to VEGF and hypoxia via an Akt-dependent mechanism. In response to hyperoxia/hypoxia, Nf1^+/− retinas exhibited increased vessel dropout and neovascularization when compared with WT retinas. Neovascularization was similar between Nf1^+/− and Nf1^flox/+;Tie2cre retinas, but capillary drop out in Nf1^flox/+;Tie2cre retinas was significantly reduced when compared with Nf1^+/− retinas.

Conclusions

These data suggest that neurofibromin expression is essential for controlling endothelial cell proliferation and retinal neovascularization and therapies targeting neurofibromin-deficient EC may be beneficial.

Pediatric malignancies in neurofibromatosis type 1: A population-based cohort study

Neurofibromatosis type 1 (NF1) is a cancer predisposition syndrome with an incidence of 1:2,000. Patients with NF1 have an increased cancer risk and mortality, but there are no population‐based cohort studies specifically investigating the risk of childhood malignancies. We used the Finnish NF1 cohort to analyze the incidence, risk and prognosis of malignancies in NF1 patients <20 years of age. Persons born in 1987–2011 were included, and 524 persons were followed through the files of the Finnish Cancer Registry from birth up to age 20 years. This amounted to 8,376 person years. Fifty‐three patients had cancer <20 years of age, yielding a standardized incidence ratio (SIR) of 35.6. The most frequent location of pediatric cancers was the central nervous system (CNS); there were 45 cases and the SIR was 115.7. Exclusion of 22 optic pathway gliomas (OPGs) gave an SIR of 59.1 for the CNS and 21.6 for all cancers. There were nine malignant peripheral nerve sheath tumors (MPNSTs); their cumulative risk was 2.7% by age 20. No cases of leukemia were observed. NF1 patients showed considerable excess mortality with a standardized mortality ratio (SMR) of 73.1. The survival of NF1 patients with CNS tumors other than OPGs did not differ from that of non‐NF1 controls (HR 0.64, 95% CI 0.23 to 1.76). In conclusion, brain tumors in childhood and MPNSTs in adolescence are malignancies of major concern in patients with NF1. The risk for myeloid malignancies may not be as high as suggested in the literature.

What's new?

Patients with neurofibromatosis type 1 (NF1) are known to have a high risk of various cancers. What has not been well‐studied, however, are the types of cancers that are most common among children with NF1, and how those cancers impact mortality. In this cohort study, the authors found that malignancies do cause increased mortality in patients under age 20. Brain tumors in childhood and malignant peripheral nerve sheath tumors (MPNSTs) in adolescence are of particular concern. On the other hand, the risk of myeloid malignancies may be lower than previously assumed.

Prevalence of Strabismus Among Children With Neurofibromatosis Type 1 Disease With and Without Optic Pathway Glioma

PURPOSE

To evaluate the prevalence of strabismus in neurofibromatosis type 1 (NF-1) by comparing children with normal neuroimaging to those with optic pathway glioma.

METHODS

A retrospective data collection of all children with NF-1 with neuroimaging studies examined at a single medical center between 2000 and 2016.

RESULTS

Of the 198 children with NF-1 reviewed, 109 (55%) were male, 121 (61%) had normal neuroimaging, and 77 (39%) had an optic pathway glioma. Mean age at presentation was 6.3 ± 4.7 years and mean follow-up was 4.8 ± 3.1 years. Strabismus was present in 29 (15%) children and was significantly more prevalent in children with NF-1 with optic pathway glioma (21 of 77 [27%]) than in those with normal neuroimaging (8 of 121 [7%], P < .001). Sensory strabismus was only found in children with optic pathway glioma, accounting for most cases (12 of 21 [57%]). A strong association between strabismus and optic pathway glioma is demonstrated by an odds ratio of 5.29 (P < .001). Children with NF-1 with optic pathway glioma have a 4.13 times higher relative risk of developing strabismus than children with NF-1 without it (P = .001). The direction of ocular misalignment in children with NF-1 with optic pathway glioma was not significantly different than that observed in children without optic pathway glioma (P = .197, Fisher's exact test). Only 5 (17%) children with NF-1 with strabismus (3 with optic pathway glioma) underwent corrective surgery to align their eyes.

CONCLUSIONS

Optic pathway glioma in children with NF-1 is associated with an increased risk of strabismus that is often sensory. Although exotropia is the most common ocular misalignment associated with optic pathway glioma, the direction of strabismus cannot be used as an accurate predictor for its presence. [J Pediatr Ophthalmol Strabismus. 2019;56(1):19-22.].

Neurofibromatosis type 1: State-of-the-art review with emphasis on pulmonary involvement

Neurofibromatosis type 1 (NF-1), also known as von Recklinghausen's disease, is an autosomal dominant dysplasia of the ectoderm and mesoderm with a variable clinical expression, but near-complete penetrance before the age of 5 years. The estimated incidence is 1 in 3000 births. NF-1 is characterized by collections of neurofibromas, café-au-lait spots, axillary and inguinal freckling, and pigmented hamartomas in the iris (Lisch nodules). Pulmonary manifestations of NF-1, which usually include bilateral basal reticulations and apical bullae and cysts, are reported in 10-20% of adult patients. Clinically, neurofibromatosis-associated diffuse lung disease (NF-DLD) usually presents with nonspecific respiratory symptoms, including dyspnea on exertion, shortness of breath, and chronic cough or chest pain, at the time of diagnosis. Computed tomography (CT) is highly accurate for the identification and characterization of NF-DLD; it is the most reliable method for the diagnosis of this lung involvement. Various CT findings of NF-DLD, including cysts, bullae, ground-glass opacities, bibasilar reticular opacities, and emphysema, have been described in patients with NF-1. The typical CT pattern, however, is characterized by upper-lobe cystic and bullous disease, and basilar interstitial lung disease. Currently, the goal of NF-DLD treatment is the earliest possible diagnosis, focusing on symptom relief and interventions that positively alter the course of the disease, such as smoking cessation. The aim of this review is to describe the main clinical, pathological, and imaging aspects of NF-1, with a focus on pulmonary involvement.

Monitoring optic chiasmatic-hypothalamic glioma volumetric changes by MRI in children under clinical surveillance or chemotherapy

PURPOSE

Optic pathway gliomas represent 5% of pediatric brain tumors and are typically low-grade lesions. Because of their unpredictable clinical course, adequate treatment approaches have been controversial, involving surveillance, surgery, chemotherapy, and radiotherapy. In this study, we use volumetric imaging to compare evolution of optic chiasmatic-hypothalamic gliomas (OCHG) treated with and without chemotherapy, analyzing tumor volume variation during the overall period.

METHODS

A total of 45 brain MRI were retrospectively analyzed for 14 patients with OCHG. Volumetric assessment of the lesions was performed by a neuroradiologist, using software DISPLAY. OCHG patients were allocated into two groups: group 1 (n = 8) who underwent chemotherapy and group 2 (n = 6) who did not receive chemotherapy. Outcome analysis was performed comparing tumor volume evolution of these two groups.

RESULTS

The results showed a reduction of 4.4% of the volume of the lesions for group 1 after the end of chemotherapy, with an increase of 5.3% in volume in the late follow-up examination. For group 2, we found a slight reduction (5%) of the overall volume of the lesions, both with no statistical significance (p > 0.05).

CONCLUSIONS

From the limited series analyzed in this study, no significant differences were observed in relation to the volume change of lesions treated or not treated with chemotherapy. Larger prospective clinical trials are needed to better evaluate the effect of chemotherapy and radiological response of OCHG.

Is Schimmelpenning Syndrome Associated with Intracranial Tumors? A Case Report

Schimmelpenning syndrome is a rare, well-defined constellation of clinical phenotypes associated with the presence of nevus sebaceous and multisystem abnormalities most commonly manifested as cerebral, ocular, and skeletal defects [<xref ref-type="bibr" rid="ref1">1</xref>]. A single nucleotide mutation in the HRAS or KRAS genes resulting in genetic mosaicism is responsible for the clinical manifestations of this syndrome in the majority of cases. We report a case of an adolescent boy with Schimmelpenning syndrome with a multifocal pilocytic astrocytoma. No HRAS or KRAS gene mutations were noted in the tumor on genetic sequencing. However, glial tumors have been associated with genetic mutations of RAS upregulation, which may imply a common pathway.

Use of Optical Coherence Tomography to Detect Retinal Nerve Fiber Loss in Children With Optic Pathway Glioma

Optic pathway glioma (OPG) presents in childhood and can cause significant morbidity and visual loss. Magnetic resonance imaging (MRI) is the current imaging modality of choice for evaluation of OPG progression, but it is a relatively limited resource often requiring sedation in the pediatric age group. Additionally, OPG progression on MRI does not always correlate with clinical progression. As a result, several other modalities for evaluating OPG are being investigated, including optical coherence tomography (OCT), a readily available imaging technique in ophthalmic practice. The purpose of the present study was to examine the association between retinal nerve fiber layer (RNFL) thickness measured using OCT and optic nerve function in children with OPG with and without neurofibromatosis-1 (NF-1). A retrospective chart review was conducted to identify children diagnosed with OPG from 2001 to 2015 at a tertiary pediatric medical center. The correlation between OCT measurements and clinical visual parameters was statistically analyzed. Included were 23 children with imaging-confirmed OPG and spectral domain OCT: 10 with NF-1 (mean age at diagnosis 5.8 years) and 13 without (mean age at diagnosis 5.9 years). The glioma involved the chiasma-hypothalamus in 19 patients, optic nerve in 11, and optic tract in 7; more than one anatomic site was affected in 15. Symptoms were reported in 2 patients with NF-1 and most patients without NF-1. Visual field defects included monocular, bitemporal, nasal, and homonymous hemianopia. Initial mean RNFL was 85.4 μm in the NF-1 group and 65 μm in the non-NF-1 group. Visual acuity deteriorated in 1/10 patients and 5/13 patients, respectively. Repeated OCT showed continued RNFL thinning in 3 patients (5 eyes) in the NF-1 group and in 8 patients (11 eyes) in the non-NF-1 group, often associated with a decrease in optic nerve function. In conclusion, visual function in children with OPG is correlated with repeated OCT measurements and weakly with neuroimaging. Children without NF-1 are usually symptomatic and have a worse clinical outcome. These findings may have important implications when considering initiating, continuing or stopping chemotherapy for OPG. The application of OCT in the assessment of OPG and the correlation of the findings to clinical progression can have a significant impact on OPG patient management.

The causes and consequences of pituitary gigantism

In the general population, height is determined by a complex interplay between genetic and environmental factors. Pituitary gigantism is a rare but very important subgroup of patients with excessive height, as it has an identifiable and clinically treatable cause. The disease is caused by chronic growth hormone and insulin-like growth factor 1 secretion from a pituitary somatotrope adenoma that forms before the closure of the epiphyses. If not controlled effectively, this hormonal hypersecretion could lead to extremely elevated final adult height. The past 10 years have seen marked advances in the understanding of pituitary gigantism, including the identification of genetic causes in ~50% of cases, such as mutations in the AIP gene or chromosome Xq26.3 duplications in X-linked acrogigantism syndrome. Pituitary gigantism has a male preponderance, and patients usually have large pituitary adenomas. The large tumour size, together with the young age of patients and frequent resistance to medical therapy, makes the management of pituitary gigantism complex. Early diagnosis and rapid referral for effective therapy appear to improve outcomes in patients with pituitary gigantism; therefore, a high level of clinical suspicion and efficient use of diagnostic resources is key to controlling overgrowth and preventing patients from reaching very elevated final adult heights.

Correlation of peripapillary retinal nerve fibre layer thickness with visual acuity in paediatric patients affected by optic pathway glioma

PURPOSE

To evaluate peripapillary retinal nerve fibre layer (RNFL) thickness, measured by spectral-domain optical coherence tomography (SD-OCT), as a surrogate of visual function in a population of paediatric patients affected by optic pathway glioma (OPG) associated with neurofibromatosis type 1 (NF1).

METHODS

A total of 38 paediatric patients (66 eyes) affected by MRI-proven OPG were included. Each patient underwent complete ophthalmological examination, including age-appropriate visual acuity (VA) assessment and RNFL analysis by SD-OCT. Visual acuity was classified as normal or pathologic using age-based normative data. Visual acuity was correlated to mean RNFL thickness of the whole peripapillary area and of each single analyzed sector (nasal, superior, temporal, inferior).

RESULTS

Visual acuity was normal in 43 (65%) and pathologic in 23 (35%) eyes. Mean parapapillary RNFL thickness of each analyzed sector was significantly lower in eyes with abnormal VA (p < 0.05). The best balanced cut-off value of global RNFL thickness allowing to discriminate between eyes with normal and pathologic VA was 76.25 μm (91%, 76%, 67% and 94% of sensitivity, specificity, positive and negative predicting value, respectively). Considering best balanced cut-off values of other analyzed RNFL sectors, the superior (p = 0.0029) and the inferior (p = 0.0024) sectors reached the higher sensitivity (87% and 87%, respectively) and specificity (81% and 79%, respectively).

CONCLUSION

Retinal nerve fibre layer thickness is directly related to VA in children affected by NF1-related OPG, and should be considered as a potential surrogate marker of VA. Retinal nerve fibre layer thickness cut-off values can be used in paediatric patients to discriminate false-positive results obtained by VA measurement.

Genetically engineered minipigs model the major clinical features of human neurofibromatosis type 1

Neurofibromatosis Type 1 (NF1) is a genetic disease caused by mutations in Neurofibromin 1 (NF1). NF1 patients present with a variety of clinical manifestations and are predisposed to cancer development. Many NF1 animal models have been developed, yet none display the spectrum of disease seen in patients and the translational impact of these models has been limited. We describe a minipig model that exhibits clinical hallmarks of NF1, including café au lait macules, neurofibromas, and optic pathway glioma. Spontaneous loss of heterozygosity is observed in this model, a phenomenon also described in NF1 patients. Oral administration of a mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor suppresses Ras signaling. To our knowledge, this model provides an unprecedented opportunity to study the complex biology and natural history of NF1 and could prove indispensable for development of imaging methods, biomarkers, and evaluation of safety and efficacy of NF1-targeted therapies.

Surveillance magnetic resonance imaging for isolated optic pathway gliomas: is gadolinium necessary?

BACKGROUND

Pediatric optic pathway gliomas are typically indolent but have a variable clinical course. Treatment is dictated by symptoms and changes on contrast-enhanced MRI examinations. Gadolinium retention in children has motivated parsimonious use of gadolinium-based contrast agents.

OBJECTIVES

To determine surveillance MR factors that motivate changes in tumor-directed therapies and extrapolate cost-efficacy of a non-contrast follow-up protocol.

MATERIALS AND METHODS

Using an imaging database search we identified children with isolated optic pathway gliomas and ≥3 follow-up contrast-enhanced MRIs. We reviewed medical records and imaging for: (1) coincident changes on contrast-enhanced MRI and tumor-directed therapy, (2) demographics and duration of follow-up, (3) motivations for intervention, (4) assessment of gadolinium-based contrast agents' utility and (5) health care utilization data. We assessed cost impact in terms of relative value unit (RVU) burden.

RESULTS

We included 17 neurofibromatosis type 1 (NF1) and 21 non-NF1 patients who underwent a median 16.9 and 24.3 cumulative contrast-enhanced MR exams over 7.7 years and 8.1 years of follow-up, respectively. Eight children (one with NF1) had intervention based on contrast-enhanced MR findings alone. For these eight, increased tumor size was the only common feature, and it was apparent on non-contrast T2 sequences. For the median patient, a non-contrast follow-up protocol could result in 15.9 (NF1) and 23.3 (non-NF1) fewer gadolinium-based contrast agent administrations, and a 39% lower yearly RVU burden.

CONCLUSION

Pediatric patients with isolated optic pathway gliomas undergo a large number of routine contrast-enhanced MR follow-up exams. Gadolinium might not be needed for these exams to inform management decisions. Secondary benefits of a non-contrast follow-up protocol include decreased cost and risk to the patient.

Neurocutaneous Disorders

PURPOSE OF REVIEW

This article presents an up-to-date summary of the genetic etiology, diagnostic criteria, clinical features, and current management recommendations for the most common neurocutaneous disorders encountered in clinical adult and pediatric neurology practices.

RECENT FINDINGS

The phakomatoses are a phenotypically and genetically diverse group of multisystem disorders that primarily affect the skin and central nervous system. A greater understanding of the genetic and biological underpinnings of numerous neurocutaneous disorders has led to better clinical characterization, more refined diagnostic criteria, and improved treatments in neurofibromatosis type 1, Legius syndrome, neurofibromatosis type 2, Noonan syndrome with multiple lentigines, tuberous sclerosis complex, Sturge-Weber syndrome, and incontinentia pigmenti.

SUMMARY

Neurologists require a basic knowledge of and familiarity with a wide variety of neurocutaneous disorders because of the frequent involvement of the central and peripheral nervous systems. A simple routine skin examination can often open a broad differential diagnosis and lead to improved patient care.

Pediatric Brain Tumors

PURPOSE OF REVIEW

This article describes the most common pediatric brain tumors and highlights recent developments in their diagnosis and treatment strategies.

RECENT FINDINGS

We are in the midst of a molecular era for pediatric brain tumors. Genetic and epigenetic profiling of tumors has impacted their diagnosis, allowing for the subgrouping of heterogeneous tumor groups and leading to the complete renaming of some tumor types. These advances are reflected in the new 2016 World Health Organization classification. For example, primitive neuroectodermal tumors have been completely eliminated and replaced by subgroups defined by the absence or presence of specific chromosomal amplification. Medulloblastomas, diffuse astrocytomas, and ependymomas now have specific subtypes that are based on defining molecular features. More recent epigenetic-based subgrouping of atypical teratoid/rhabdoid tumors have not yet made it into the official classification system, but will surely have an impact on how these tumors are regarded in future preclinical and clinical trials.

SUMMARY

Genetic and epigenetic data are changing how pediatric brain tumors are diagnosed, are leading to new guidelines for how treatment outcome analyses can be organized, and are offering molecular targets that can be used for the development of novel therapies.

Macrocephaly: Solving the Diagnostic Dilemma

Macrocephaly is a relatively common clinical condition affecting up to 5% of the pediatric population. It is defined as an abnormally large head with an occipitofrontal circumference greater than 2 standard deviations above the mean for a given age and sex. Megalencephaly refers exclusively to brain overgrowth exceeding twice the standard deviation. Macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, whereas megalencephaly is more often syndromic. Megalencephaly can be divided into 2 subtypes: metabolic and developmental, caused by genetic defects in cellular metabolism and alterations in signaling pathways, respectively. Neuroimaging plays an important role in the evaluation of macrocephaly, especially in the metabolic subtype which may not be overtly apparent clinically. This article outlines the diverse etiologies of macrocephaly, delineates their clinical and radiographic features, and suggests a clinicoradiological algorithm for evaluation.

Identification of Mutation Regions on NF1 Responsible for High- and Low-Risk Development of Optic Pathway Glioma in Neurofibromatosis Type I

Neurofibromatosis type I is a rare neurocutaneous syndrome resulting from loss-of-function mutations of NF1. The present study sought to determine a correlation between mutation regions on NF1 and the risk of developing optic pathway glioma (OPG) in patients with neurofibromatosis type I. A total of 215 patients with neurofibromatosis type I, from our clinic or previously reported literature, were included in the study after applying strict inclusion and exclusion criteria. Of these, 100 patients with OPG were classified into the OPG group and 115 patients without OPG (aged ≥ 10 years) were assigned to the Non-OPG group. Correlation between different mutation regions and risk of OPG was analyzed. The mutation clustering in the 5′ tertile of NF1 was not significantly different between OPG and Non-OPG groups (P = 0.131). Interestingly, patients with mutations in the cysteine/serine-rich domain of NF1 had a higher risk of developing OPG than patients with mutations in other regions [P = 0.019, adjusted odds ratio (OR) = 2.587, 95% confidence interval (CI) = 1.167–5.736], whereas those in the HEAT-like repeat region had a lower risk (P = 0.036, adjusted OR = 0.396, 95% CI = 0.166–0.942). This study confirms a new correlation between NF1 genotype and OPG phenotype in patients with neurofibromatosis type I, and provides novel insights into molecular functions of neurofibromin.

Graph complexity analysis identifies an ETV5 tumor-specific network in human and murine low-grade glioma

Conventional differential expression analyses have been successfully employed to identify genes whose levels change across experimental conditions. One limitation of this approach is the inability to discover central regulators that control gene expression networks. In addition, while methods for identifying central nodes in a network are widely implemented, the bioinformatics validation process and the theoretical error estimates that reflect the uncertainty in each step of the analysis are rarely considered. Using the betweenness centrality measure, we identified Etv5 as a potential tissue-level regulator in murine neurofibromatosis type 1 (Nf1) low-grade brain tumors (optic gliomas). As such, the expression of Etv5 and Etv5 target genes were increased in multiple independently-generated mouse optic glioma models relative to non-neoplastic (normal healthy) optic nerves, as well as in the cognate human tumors (pilocytic astrocytoma) relative to normal human brain. Importantly, differential Etv5 and Etv5 network expression was not directly the result of Nf1 gene dysfunction in specific cell types, but rather reflects a property of the tumor as an aggregate tissue. Moreover, this differential Etv5 expression was independently validated at the RNA and protein levels. Taken together, the combined use of network analysis, differential RNA expression findings, and experimental validation highlights the potential of the computational network approach to provide new insights into tumor biology.

Visual function assessed by visually evoked potentials in optic pathway low-grade gliomas with and without neurofibromatosis type 1

PURPOSE

To investigate the contribution of full-field transient pattern-reversal visually evoked potentials (PRVEP) on cross-sectional evaluations of visual function in patients with and without neurofibromatosis type 1 (NF1) affected by optic pathway low-grade gliomas (OPLGG).

METHODS

Participants were children and adolescents referred for visual function evaluation and receiving treatment for OPLGG, linked (NF1-OPLGG) or not to NF1 (Non-NF1-OPLGG). An age-adjusted control group was included for comparison. Monocular full-field PRVEPs were recorded from each eye in accordance with ISCEV standards. Parameters of peak-to-peak P100 amplitude (µV) and P100 peak time (ms) were measured. Cutoff normative values obtained from controls for 15' and 60' check sizes were ≥ 9.0 µV for N75-P100 amplitude and ≤ 103.0 ms for P100 peak time. The association of age, gender, tumor resection and NF1 with P100 amplitude reduction and P100 peak time delay was explored by Firth logistic regression modeling.

RESULTS

Participants were 30 patients (15 males, 60% Non-NF1) with ages from 3.6 to 19.9 years (mean ± SD = 9.2 ± 3.8 years; median = 8.4 years) and 19 controls (12 males) with ages from 3.7 to 19.9 years (mean ± SD = 10.4 ± 4.9 years; median = 9.5 years). Overall, 68% of tested eyes presented reduced P100 amplitudes for both check sizes (46% in the NF-1 and 83% in the Non-NF1) and delayed P100 for both check sizes (38% in NF1 and 89% in Non-NF1). Absence of NF1 adjusted for age, gender and tumor resection was significantly associated with marginally reduced P100 amplitude for 15' checks [odds ratio (OR): 6.26; 95% confidence interval (CI) = 0.96-40.94; p = 0.055].

CONCLUSIONS

Full-field PRVEP on cross-sectional evaluations contributed to detect visual dysfunction in two-thirds of patients with OPLGG by highlighting subclinical evidence of visual loss. Abnormalities were more frequent and more severe in OPLGG not linked to NF1 than in NF1-OPLGG; however, there was a difference in surgical management between these groups. PRVEP parameters may provide reliable evidence of visual pathway involvement in OPLGG, helping to hasten treatment before optic atrophy is detected.

Investigation of retinal nerve fiber layer thickness and ganglion cell layer-inner plexiform layer thickness in patients with optic pathway gliomas

PURPOSE

This study aimed to compare the optical coherence tomography (OCT) findings of optic pathway glioma (OPG) patients (sporadic or secondary to neurofibromatosis type 1, NF1) with NF1 without OPG patients and healthy controls.

METHODS

This was a prospective, case-control study in which 27 patients (13 with OPGs and 14 with NF1 without OPGs) and 13 control subjects were included. The retinal nerve fiber layer (RNFL) thickness, macular thickness, and ganglion cell layer-inner plexiform layer (GCL-IPL) thickness findings measured using OCT and the results were compared between the groups.

RESULTS

The macular thickness was significantly lower in the OPG group than in the control group and the NF1 patients without OPGs group (p < 0.001). The GCL-IPL thickness was lower in OPG group than in the control group and the NF1 patients without OPG group (p < 0.001). The RNFL thickness was lower in the OPG group than in the control group and the NF1 patients without OPG group (p < 0.001). There was a statistically significantly negative correlation between the visual acuity (log of the minimum angle of resolution, logMAR) and all the other parameters (macular, RNFL, and GCL-IPL thicknesses). All the parameters were found to positively correlate with each other.

CONCLUSIONS

OCT measurements (macular thickness, RNFL, and GCL-IPL thicknesses) can be used to monitor the disease in those patients with suspected OPGs; however, this should be verified with a larger case series.

Challenges in the management of childhood low-grade glioma in a developing country

BACKGROUND

Treatment modality impacts outcome of childhood low-grade glioma (LGG). Optimizing management in developing countries can be challenging. This study evaluates the clinical characteristics, treatment, and factors influencing outcome of childhood LGG in Saudi Arabia.

PATIENTS AND METHODS

This study retrospectively evaluated 59 children consecutively diagnosed with LGG between January 2001 and June 2016.

RESULTS

Median age at diagnosis was 6.0 years. Pilocytic astrocytoma represented 64.9% of cases. The anatomic site was cerebellar in 23.7%, cerebral in 18.6%, hypothalamic-optic pathway in 33.9%, and midline in 23.7%. The 5-year overall survival (OS) and progression-free survival (PFS) were 90.6 ± 4.7 and 54.3 ± 8.4%, respectively. Initial treatment was observation in 28.8%, surgery alone in 35.6%, chemotherapy in 13.6%, radiotherapy in 5.1%, and combined in 16.9% of cases. The corresponding 5-year PFS was 56.3 ± 15.6, 53.3 ± 14.0, 22.9 ± 19.7, 33.3 ± 27.2, and 88.9 ± 10.5%, respectively (p = 0.006). Among the 61% who had surgical intervention (either alone or in combination with other therapies), 22% achieved complete resection with 5-year radiation/progression-free survival (RPFS) of 87.5 ± 11.7% compared to 27.6 ± 10.8% for subtotal resection/biopsy and 62.2 ± 17.0% for no surgery (p = 0.013). Adjuvant therapy for residual tumor improved survival with 5-year PFS of 66.7 ± 19.2% for chemotherapy and 100% for radiotherapy compared to 12.5 ± 11.4% for observation (p = 0.033).

CONCLUSIONS

We identified variability in the outcomes of LGG. Fewer surgeries with lower rates of total resection were noted, compared to reports from international cooperative groups. The extent of resection was predictive of RPFS. Adjuvant therapy improved the outcome of patients with residual disease, resulting in PFS rates comparable to international data.

Pediatric High Grade Gliomas in the Context of Cancer Predisposition Syndromes

Germline mutations in cancer causing genes result in high risk of developing cancer throughout life. These cancer predisposition syndromes (CPS) are especially prevalent in childhood brain tumors and impact both the patient’s and other family members’ survival. Knowledge of specific CPS may alter the management of the cancer, offer novel targeted therapies which may improve survival for these patients, and enables early detection of other malignancies. This review focuses on the role of CPS in pediatric high grade gliomas (PHGG), the deadliest group of childhood brain tumors. Genetic aspects and clinical features are depicted, allowing clinicians to identify and diagnose these syndromes. Challenges in the management of PHGG in the context of each CPS and the promise of innovative options of treatment and surveillance guidelines are discussed with the hope of improving outcome for individuals with these devastating syndromes.

Pediatric Glioma at the Optic Pathway and Thalamus

Gliomas are the most common pediatric tumors of the central nervous system. In this review, we discuss the clinical features, treatment paradigms, and evolving concepts related to two types of pediatric gliomas affecting two main locations: the optic pathway and thalamus. In particular, we discuss recently revised pathologic classification, which adopting molecular parameter. We believe that our review contribute to the readers' better understanding of pediatric glioma because pediatric glioma differs in many ways from adult glioma according to the newest advances in molecular characterization of this tumor. A better understanding of current and evolving issues in pediatric glioma is needed to ensure effective management decision.

Insights into optic pathway glioma vision loss from mouse models of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome caused by mutations in the NF1 gene. The NF1-encoded protein (neurofibromin) is an inhibitor of the oncoprotein RAS and controls cell growth and survival. Individuals with NF1 are prone to developing low-grade tumors of the optic nerves, chiasm, tracts, and radiations, termed optic pathway gliomas (OPGs), which can cause vision loss. A paucity of surgical tumor specimens and of patient-derived xenografts for investigative studies has limited our understanding of human NF1-associated OPG (NF1-OPG). However, mice genetically engineered to harbor Nf1 gene mutations develop optic gliomas that share many features of their human counterparts. These genetically engineered mouse (GEM) strains have provided important insights into the cellular and molecular determinants that underlie mouse Nf1 optic glioma development, maintenance, and associated vision loss, with relevance by extension to human NF1-OPG disease. Herein, we review our current understanding of NF1-OPG pathobiology and describe the mechanisms responsible for tumor initiation, growth, and associated vision loss in Nf1 GEM models. We also discuss how Nf1 GEM and other preclinical models can be deployed to identify and evaluate molecularly targeted therapies for OPG, particularly as they pertain to future strategies aimed at preventing or improving tumor-associated vision loss in children with NF1.

Defining the temporal course of murine neurofibromatosis-1 optic gliomagenesis reveals a therapeutic window to attenuate retinal dysfunction

Background

Optic gliomas arising in the neurofibromatosis type 1 (NF1) cancer predisposition syndrome cause reduced visual acuity in 30%-50% of affected children. Since human specimens are rare, genetically engineered mouse (GEM) models have been successfully employed for preclinical therapeutic discovery and validation. However, the sequence of cellular and molecular events that culminate in retinal dysfunction and vision loss has not been fully defined relevant to potential neuroprotective treatment strategies.

Methods

Nf1flox/mut GFAP-Cre (FMC) mice and age-matched Nf1flox/flox (FF) controls were euthanized at defined intervals from 2 weeks to 24 weeks of age. Optic nerve volumes were measured, and optic nerves/retinae analyzed by immunohistochemistry. Optical coherence tomography (OCT) was performed on anesthetized mice. FMC mice were treated with lovastatin from 12 to 16 weeks of age.

Results

The earliest event in tumorigenesis was a persistent elevation in proliferation (4 wk), which preceded sustained microglia numbers and incremental increases in S100+ glial cells. Microglia activation, as evidenced by increased interleukin (IL)-1β expression and morphologic changes, coincided with axonal injury and retinal ganglion cell (RGC) apoptosis (6 wk). RGC loss and retinal nerve fiber layer (RNFL) thinning then ensued (9 wk), as revealed by direct measurements and live-animal OCT. Lovastatin administration at 12 weeks prevented further RGC loss and RNFL thinning both immediately and 8 weeks after treatment completion.

Conclusion

By defining the chronology of the cellular and molecular events associated with optic glioma pathogenesis, we demonstrate critical periods for neuroprotective intervention and visual preservation, as well as establish OCT as an accurate biomarker of RGC loss.

Neurofibromatosis type 1 and optic pathway glioma: Molecular interplay and therapeutic insights

Children with neurofibromatosis type 1 (NF1) are predisposed to develop central nervous system neoplasms, the most common of which are low-grade gliomas (LGGs). The absence of human NF1 associated LGG-derived cell lines, coupled with an inability to generate patient-derived xenograft models, represents barriers to profile molecularly targeted therapies for these tumors. Thus, genetically engineered mouse models have been identified to evaluate the interplay between Nf1-deficient tumor cells and nonneoplastic stromal cells to evaluate potential therapies for these neoplasms. Future treatments might also consider targeting the nonneoplastic cells in NF1-LGGs to reduce tumor growth and neurologic morbidity in affected children.

Retinal Vascular and Neural Remodeling Secondary to Optic Nerve Axonal Degeneration: A Study Using OCT Angiography

PURPOSE

To investigate the pathophysiologic interrelations between retinal neural and vascular changes, detected by spectral-domain OCT (SD-OCT) and OCT angiography (OCTA), resulting from optic nerve axonal degeneration.

DESIGN

Institutional, observational, case-control study with prospective enrollment.

PARTICIPANTS

Twenty-six patients affected by optic nerve axonal degeneration secondary to posterior optic pathway glioma (OPG) involving the chiasma, the postchiasmatic visual pathway, or both (but not involving optic nerves) and 24 gender- and age-matched healthy participants were included consecutively.

METHODS

Best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study score) was measured and SD-OCT (Heidelberg Engineering, Heidelberg, Germany) and OCTA (Nidek RS-3000 Advance device; Nidek, Gamagori, Japan) were performed.

MAIN OUTCOME MEASURES

Peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell complex (GCC), and inner nuclear layer (INL) were analyzed using SD-OCT. The radial peripapillary capillary plexus, full-thickness peripapillary retina vascularization, and the macular superficial plexus (SCP) and deep capillary plexus (DCP) were analyzed using OCTA.

RESULTS

Peripapillary retinal nerve fiber layer and GCC thickness were reduced in eyes affected by OPG (P < 0.0001). Radial peripapillary capillary plexus perfusion also was reduced, as well as full-thickness peripapillary retina vascularization (P < 0.01 and P < 0.05, respectively). Macular DCP perfusion was reduced in eyes affected by OPG, whereas macular SCP perfusion did not differ between the 2 groups (P < 0.05 and P > 0.05, respectively). Global pRNFL thickness reduction correlated with the reduction of peripapillary perfusion (P < 0.01). Macular GCC thickness reduction did not correlate with SCP reduction (P > 0.05). The reduction of macular DCP perfusion did not correlate with inner nuclear layer thickness (P > 0.05).

CONCLUSIONS

Retinal neural remodeling secondary to optic nerve axonal degeneration resulting from OPG located at or posterior to the chiasm is accompanied by a secondary retinal vascular remodeling involving not only the peripapillary area, but also the macular area (DCP).

Genotype-Phenotype Correlation in NF1: Evidence for a More Severe Phenotype Associated with Missense Mutations Affecting NF1 Codons 844-848

Neurofibromatosis type 1 (NF1), a common genetic disorder with a birth incidence of 1:2,000-3,000, is characterized by a highly variable clinical presentation. To date, only two clinically relevant intragenic genotype-phenotype correlations have been reported for NF1 missense mutations affecting p.Arg1809 and a single amino acid deletion p.Met922del. Both variants predispose to a distinct mild NF1 phenotype with neither externally visible cutaneous/plexiform neurofibromas nor other tumors. Here, we report 162 individuals (129 unrelated probands and 33 affected relatives) heterozygous for a constitutional missense mutation affecting one of five neighboring NF1 codons-Leu844, Cys845, Ala846, Leu847, and Gly848-located in the cysteine-serine-rich domain (CSRD). Collectively, these recurrent missense mutations affect ∼0.8% of unrelated NF1 mutation-positive probands in the University of Alabama at Birmingham (UAB) cohort. Major superficial plexiform neurofibromas and symptomatic spinal neurofibromas were more prevalent in these individuals compared with classic NF1-affected cohorts (both p < 0.0001). Nearly half of the individuals had symptomatic or asymptomatic optic pathway gliomas and/or skeletal abnormalities. Additionally, variants in this region seem to confer a high predisposition to develop malignancies compared with the general NF1-affected population (p = 0.0061). Our results demonstrate that these NF1 missense mutations, although located outside the GAP-related domain, may be an important risk factor for a severe presentation. A genotype-phenotype correlation at the NF1 region 844-848 exists and will be valuable in the management and genetic counseling of a significant number of individuals.

Neurofibromatosis Clinical Trial Consortium

Neurofibromatosis type 1 and type 2, affecting both children and adults, often results in devastating complications. The rapid unravelling of the genetic underpinnings of these unique disorders has led to the development of novel therapies, especially molecular-targeted therapies. To facilitate clinical trial development, the Neurofibromatosis Clinical Trial Consortium (NFCTC) was established in 2006 by the Department of Defense. Over the past decade, the Consortium has successfully completed studies for children and adults with neurofibromatosis type 1 and plexiform neurofibromas, neurocognitive challenges, low-grade gliomas, and malignant peripheral nerve sheath tumors. In addition, a study for children and adults with neurofibromatosis type 2 and acoustic schwannomas is near completion. The NFCTC has now been expanded to 19 sites in the United Stated and Australia. Mechanisms have been put in place to work closely with other consortia, foundations, and industry to expeditiously translate preclinical discoveries into clinical trials.

Optic Pathway Gliomas in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is one of the most common brain tumor predisposition syndromes, in which affected children are prone to the development of low-grade gliomas. While NF1-associated gliomas can be found in several brain regions, the majority arise in the optic nerves, chiasm, tracts, and radiations (optic pathway gliomas; OPGs). Owing to their location, 35-50% of affected children present with reduced visual acuity. Unfortunately, despite tumor stabilization following chemotherapy, vision does not improve in most children. For this reasons, more effective therapies are being sought that reflect a deeper understanding of the NF1 gene and the use of authenticated Nf1 genetically-engineered mouse strains. The implementation of these models for drug discovery and validation has galvanized molecularly-targeted clinical trials in children with NF1-OPG. Future research focused on defining the cellular and molecular factors that underlie optic glioma development and progression also has the potential to provide personalized risk assessment strategies for this pediatric population.

Optical coherence tomography as a marker of vision in children with optic pathway gliomas

PURPOSE

Optic pathway gliomas (OPG) represent an important cause of visual loss in pediatric population. The indication of treatment is based on clinical or neuroimaging progression. Visual acuity loss is the most important symptom of disease progression, but children with OPG are frequently unable to complete the testing of visual function. Optical coherence tomography (OCT) was suggested as an objective tool for visual assessment. A literature review was performed in order to determine the role of retinal OCT as a surrogate marker of vision in children with OPG.

METHODS

The search was performed using PubMed, Embase, and Web of Science databases and was restricted to articles published in English between 2000 and 2016, with a minimum of ten participants enrolled.

RESULTS

Eleven studies met the eligibility criteria and were included in the present review. Both neurofibromatosis-1 associated and sporadic OPG were investigated.

CONCLUSIONS

Retinal OCT is a promising tool to be considered as a screening or follow-up test in children with OPG, and further multicenter research is encouraged.

Measurements of Retinal Nerve Fiber Thickness and Ganglion Cell Complex in Neurofibromatosis Type 1, with and Without Optic Pathway Gliomas: A Case Series

PURPOSE

The aim of this study was to investigate differences in retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thicknesses in neurofibromatosis 1 (NF1) cases, with and without optic pathway gliomas (OPGs).

MATERIALS AND METHODS

In total, 33 eyes of 33 subjects were evaluated in this prospective observational case series. Twenty-one patients with a diagnosis of NF1 were enrolled. Patients with NF1 and OPGs were included in Group 1 (n = 9), and patients with NF1 without OPGs were included in Group 2 (n = 12). The control group (Group 3) was comprised of 12 age- and sex-matched subjects with no history of ophthalmic or systemic diseases. All of the subjects underwent complete ophthalmic examinations, including best-corrected visual acuity (BCVA), slit lamp microscopy, and indirect ophthalmoscopy. Additionally, optical coherence tomography (OCT) measurements were obtained.

RESULTS

There were no statistically significant between-group differences in age and sex (p = 0.227 and 0.986, respectively). The average RNFL thickness in Group 1 (NF1 patients with OPGs) was significantly lower than in Groups 2 and 3 (86.6 ± 22.5, 107.4 ± 6.65, and 108.4 ± 5.05 µm, respectively; p = 0.001). Furthermore, the average GCC thickness in Group 1 was significantly lower than in Groups 2 and 3 (78.6 ± 16.3, 94.8 ± 3.55, and 94.9 ± 3.82 µm, respectively; p < 0.001).

CONCLUSIONS

Both RNFL and GCC thicknesses were significantly lower in NF1 patients with OPGs. The use of OCT to quantify damage to the visual pathway may enable earlier detection of OPGs in NF1 patients.

Ophthalmic manifestations in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a relatively common multisystemic inherited disease and has been extensively studied by multiple disciplines. Although genetic testing and confirmation are available, NF1 remains a clinical diagnosis. Many manifestations of NF1 involve the eye and orbit, and the ophthalmologist, therefore, plays a significant role in the diagnosis and treatment of NF1 patients. Improvements in diagnostic and imaging instruments have provided new insight to study the ophthalmic manifestations of the disease. We provide a comprehensive and up-to-date overview of the ocular and orbital manifestations of NF1.

Optic Pathway Gliomas in Neurofibromatosis Type 1: An Update: Surveillance, Treatment Indications, and Biomarkers of Vision

Optic pathway gliomas (OPGs) occur in 15%-20% of children with neurofibromatosis type 1 (NF1), leading to visual deficits in fewer than half of these individuals. The goal of chemotherapy is to preserve vision, but vision loss in NF1-associated OPG can be unpredictable. Determining which child would benefit from chemotherapy and, equally important, which child is better observed without treatment can be difficult. Unfortunately, despite frequent imaging and ophthalmologic evaluations, some children experience progressive vision loss before treatment. Indications for chemotherapy usually are based on a comprehensive, quantitative assessment of vision, but reliable vision evaluation can be challenging in young children with NF1-OPG. The ability to identify and predict impending vision loss could potentially improve management decisions and visual outcomes. To address this challenge, ophthalmologic, electrophysiologic, and imaging biomarkers of vision in NF1-OPG have been proposed. We review current recommendations for the surveillance of children at risk for NF1-OPG, outline guidelines for initiating therapy, and describe the utility of proposed biomarkers for vision.

Analysis of Survival Prognosis for Children with Symptomatic Optic Pathway Gliomas Who Received Surgery

OBJECTIVE

The feasibility and prognosis of surgical treatment for children with optic pathway gliomas (OPGs) is controversial. Therefore this study attempted to evaluate the effects of surgery and discuss prognostic factors related to the survival of children with symptomatic OPGs.

MATERIALS AND METHODS

One-hundred twenty-five children diagnosed with OPGs underwent surgery in the Department of Neurosurgery, Beijing Tiantan Hospital from 2003-2016. In this retrospective study, their demographics, clinical characteristics, treatments, and survival outcomes were investigated and summarized.

RESULTS

Among the 125 patients, the 5-year overall survival (OS) rate and progression-free survival (PFS) rate were 84.1% and 70.6%, respectively. In the univariate analysis, patients who received postoperative radiotherapy (RT) after surgery had significantly better 5-year OS and PFS rates than patients who did not receive RT (P < 0.001 for both comparisons), patients who were 3 years old had better PFS rates than younger patients (P < 0.001), and patients with endocrinology symptoms had significantly worse PFS rates than patients with other symptoms (P = 0.049). In the multiple regression analysis, postoperative treatment with RT and tumors with a lower pathologic grade were better predictors of OS. An age older than 3 years and postoperative treatment with RT were better predictors of PFS.

CONCLUSIONS

Surgery is safe and feasible for children with large volumes of OPGs and symptoms of functional impairment and obstructive hydrocephalus. Furthermore, adjuvant RT after surgery may significantly improve OS and PFS. The pathologic grade is an independent prognostic factor for OS, and the age at diagnosis is an independent prognostic factor for PFS.

Children with 5'-end NF1 gene mutations are more likely to have glioma

Objective:

To ascertain the relationship between the germline NF1 gene mutation and glioma development in patients with neurofibromatosis type 1 (NF1).

Methods:

The relationship between the type and location of the germline NF1 mutation and the presence of a glioma was analyzed in 37 participants with NF1 from one institution (Washington University School of Medicine [WUSM]) with a clinical diagnosis of NF1. Odds ratios (ORs) were calculated using both unadjusted and weighted analyses of this data set in combination with 4 previously published data sets.

Results:

While no statistical significance was observed between the location and type of the NF1 mutation and glioma in the WUSM cohort, power calculations revealed that a sample size of 307 participants would be required to determine the predictive value of the position or type of the NF1 gene mutation. Combining our data set with 4 previously published data sets (n = 310), children with glioma were found to be more likely to harbor 5′-end gene mutations (OR = 2; p = 0.006). Moreover, while not clinically predictive due to insufficient sensitivity and specificity, this association with glioma was stronger for participants with 5′-end truncating (OR = 2.32; p = 0.005) or 5′-end nonsense (OR = 3.93; p = 0.005) mutations relative to those without glioma.

Conclusions:

Individuals with NF1 and glioma are more likely to harbor nonsense mutations in the 5′ end of the NF1 gene, suggesting that the NF1 mutation may be one predictive factor for glioma in this at-risk population.

Dissecting Clinical Heterogeneity in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a common neurogenetic disorder in which affected children and adults are predisposed to the development of benign and malignant nervous system tumors. Caused by a germline mutation in the NF1 tumor suppressor gene, individuals with NF1 are prone to optic gliomas, malignant gliomas, neurofibromas, and malignant peripheral nerve sheath tumors, as well as behavioral, cognitive, motor, bone, cardiac, and pigmentary abnormalities. Although NF1 is a classic monogenic syndrome, the clinical features of the disorder and their impact on patient morbidity are variable, even within individuals who bear the same germline NF1 gene mutation. As such, NF1 affords unique opportunities to define the factors that contribute to disease heterogeneity and to develop therapies personalized to a given individual (precision medicine). This review highlights the clinical features of NF1 and the use of genetically engineered mouse models to define the molecular and cellular pathogenesis of NF1-associated nervous system tumors.

Increased Tissue Stiffness in Tumors from Mice with Neurofibromatosis-1 Optic Glioma

Children with neurofibromatosis type 1 (NF1) cancer predisposition syndrome are prone to the development of low-grade brain tumors (gliomas) within the optic pathway (optic gliomas). One of the key obstacles to developing successful therapeutic strategies for these tumors is the striking lack of information about the mechanical properties that characterize these tumors relative to non-neoplastic optic nerve tissue. To study the physical changes that may occur when an optic nerve glioma is present, we employed atomic force microscopy to measure the stiffness of healthy versus tumor-bearing optic nerve tissue. We found that the average elastic moduli of non-neoplastic and tumor-bearing optic nerves were ∼3 and ∼6 kPa, respectively. Based on previous studies implicating changes in extracellular matrix remodeling in other, related optic nerve pathological states, we found decreased expression of one major metalloproteinase protein (MMP-2) and unchanged expression of lysyl oxidase and a second metalloproteinase, MMP-9, in murine optic gliomas relative to normal non-neoplastic optic nerve. Collectively, these observations suggest a productive interplay between physical properties of mouse optic nerve gliomas and the extracellular matrix.

CNS Tumors in Neurofibromatosis

Neurofibromatosis (NF) encompasses a group of distinct genetic disorders in which affected children and adults are prone to the development of benign and malignant tumors of the nervous system. The purpose of this review is to discuss the spectrum of CNS tumors arising in individuals with NF type 1 (NF1) and NF type 2 (NF2), their pathogenic etiologies, and the rational treatment options for people with these neoplasms. This article is a review of preclinical and clinical data focused on the treatment of the most common CNS tumors encountered in children and adults with NF1 and NF2. Although children with NF1 are at risk for developing low-grade gliomas of the optic pathway and brainstem, individuals with NF2 typically manifest low-grade tumors affecting the cranial nerves (vestibular schwannomas), meninges (meningiomas), and spinal cord (ependymomas). With the identification of the NF1 and NF2 genes, molecularly targeted therapies are beginning to emerge, as a result of a deeper understanding of the mechanisms underlying NF1 and NF2 protein function. As we enter into an era of precision oncology, a more comprehensive awareness of the factors that increase the risk of developing CNS cancers in affected individuals, coupled with a greater appreciation of the cellular and molecular determinants that maintain tumor growth, will undoubtedly yield more effective therapies for these cancer predisposition syndromes.