Low-Grade Gliomas in Patients with Noonan Syndrome: Case-Based Review of the Literature

Pilocytic astrocytoma: The paradigmatic entity in low‑grade gliomas (Review)

Among low-grade gliomas, representing 10-20% of all primary brain tumours, the paradigmatic entity is constituted by pilocytic astrocytoma (PA), considered a grade 1 tumour by the World Health Organization. Generally, this tumour requires surgical treatment with an infrequent progression towards malignant gliomas. The present review focuses on clinicopathological characteristics, and reports imaging, neurosurgical and molecular features using a multidisciplinary approach. Macroscopically, PA is a slow-growing soft grey tissue, characteristically presenting in association with a cyst and forming a small mural nodule, typically located in the cerebellum, but sometimes occurring in the spinal cord, basal ganglia or cerebral hemisphere. Microscopically, it may appear as densely fibrillated areas composed of elongated pilocytic cells with bipolar 'hairlike' processes or densely fibrillated areas composed of elongated pilocytic cells with Rosenthal fibres alternating with loosely fibrillated areas with a varied degree of myxoid component. A wide range of molecular alterations have been encountered in PA, mostly affecting the MAPK signalling pathway. In detail, the most frequent alteration is a rearrangement of the BRAF gene, although other alterations include neurofibromatosis type-1 mutations, BRAFV600E mutations, KRAS mutations, fibroblast growth factor receptor-1 mutations of fusions, neurotrophic receptor tyrosine kinase family receptor tyrosine kinase fusions and RAF1 gene fusions. The gold standard of PA treatment is surgical excision with complete margin resection, achieving minimal neurological damage. Conventional radiotherapy is not required; the more appropriate treatment appears to be serial follow-up. Chemotherapy should only be applied in younger children to avoid the risk of long-term growth and developmental issues associated with radiation. Finally, if PA recurs, a new surgical approach should be performed. At present, novel therapy involving agents targeting MAPK signalling pathway dysregulation is in development, defining BRAF and MEK inhibitors as target therapeutical agents.

Germline susceptibility from broad genomic profiling of pediatric brain cancers

Background

Identifying germline predisposition in CNS malignancies is of increasing clinical importance, as it contributes to diagnosis and prognosis, and determines aspects of treatment. The inclusion of germline testing has historically been limited due to challenges surrounding access to genetic counseling, complexity in acquiring a germline comparator specimen, concerns about the impact of findings, or cost considerations. These limitations were further defined by the breadth and scope of clinical testing to precisely identify complex variants as well as concerns regarding the clinical interpretation of variants including those of uncertain significance.

Methods

In the course of conducting an IRB-approved protocol that performed genomic, transcriptomic and methylation-based characterization of pediatric CNS malignancies, we cataloged germline predisposition to cancer based on paired exome capture sequencing, coupled with computational analyses to identify variants in known cancer predisposition genes and interpret them relative to established clinical guidelines.

Results

In certain cases, these findings refined diagnosis or prognosis or provided important information for treatment planning.

Conclusions

We outline our aggregate findings on cancer predisposition within this cohort which identified 16% of individuals (27 of 168) harboring a variant predicting cancer susceptibility and contextualize the impact of these results in terms of treatment-related aspects of precision oncology.

A rare association of a high grade glioblastoma, cerebral abscess and acute lymphoblastic leukemia in a child with Noonan syndrome

Noonan syndrome is a genetic disorder frequently caused by PTPN11 mutations. Patients with Noonan syndrome are characterized by facial dysmorphism, short stature and congenital heart defects and they have a reported predisposition to malignancies such as leukemia, and solid and central nervous system tumors. Here, we report a case of a 14-year-old boy with Noonan syndrome treated for T-cell acute lymphoblastic leukemia who presented with 2 concomitant abnormalities: cerebral abscess and high grade glioblastoma. This exceptional association exhibits to a poorer prognosis and may sometimes delay the diagnosis and therefore the therapeutic intervention.

Abnormalities of pubertal development and gonadal function in Noonan syndrome

Background

Noonan syndrome (NS) is a genetic multisystem disorder characterised by variable clinical manifestations including dysmorphic facial features, short stature, congenital heart disease, renal anomalies, lymphatic malformations, chest deformities, cryptorchidism in males.

Methods

In this narrative review, we summarized the available data on puberty and gonadal function in NS subjects and the role of the RAS/mitogen-activated protein kinase (MAPK) signalling pathway in fertility. In addition, we have reported our personal experience on pubertal development and vertical transmission in NS.

Conclusions

According to the literature and to our experience, NS patients seem to have a delay in puberty onset compared to the physiological timing reported in healthy children. Males with NS seem to be at risk of gonadal dysfunction secondary not only to cryptorchidism but also to other underlying developmental factors including the MAP/MAPK pathway and genetics. Long-term data on a large cohort of males and females with NS are needed to better understand the impact of delayed puberty on adult height, metabolic profile and well-being. The role of genetic counselling and fertility related-issues is crucial.

Hereditary Conditions Associated with Elevated Cancer Risk in Childhood

Received January, 31, 2023 Revised March, 16, 2023 Accepted March, 18, 2023 Widespread use of the next-generation sequencing (NGS) technologies revealed that a significant percentage of tumors in children develop as a part of monogenic hereditary diseases. Predisposition to the development of pediatric neoplasms is characteristic of a wide range of conditions including hereditary tumor syndromes, primary immunodeficiencies, RASopathies, and phakomatoses. The mechanisms of tumor molecular pathogenesis are diverse and include disturbances in signaling cascades, defects in DNA repair, chromatin remodeling, and microRNA processing. Timely diagnosis of tumor-associated syndromes is important for the proper choice of cancer treatment, genetic counseling of families, and development of the surveillance programs. The review describes the spectrum of neoplasms characteristic of the most common syndromes and molecular pathogenesis of these diseases.

Unlocking the power of precision medicine for pediatric low-grade gliomas: molecular characterization for targeted therapies with enhanced safety and efficacy

In the past decade significant advancements have been made in the discovery of targetable lesions in pediatric low-grade gliomas (pLGGs). These tumors account for 30-50% of all pediatric brain tumors with generally a favorable prognosis. The latest 2021 WHO classification of pLGGs places a strong emphasis on molecular characterization for significant implications on prognosis, diagnosis, management, and the potential target treatment. With the technological advances and new applications in molecular diagnostics, the molecular characterization of pLGGs has revealed that tumors that appear similar under a microscope can have different genetic and molecular characteristics. Therefore, the new classification system divides pLGGs into several distinct subtypes based on these characteristics, enabling a more accurate strategy for diagnosis and personalized therapy based on the specific genetic and molecular abnormalities present in each tumor. This approach holds great promise for improving outcomes for patients with pLGGs, highlighting the importance of the recent breakthroughs in the discovery of targetable lesions.

Ganglioglioma with adverse clinical outcome and atypical histopathological features were defined by alterations in PTPN11/KRAS/NF1 and other RAS-/MAP-Kinase pathway genes

Exome-wide sequencing studies recently described PTPN11 as a novel brain somatic epilepsy gene. In contrast, germline mutations of PTPN11 are known to cause Noonan syndrome, a multisystem disorder characterized by abnormal facial features, developmental delay, and sporadically, also brain tumors. Herein, we performed a deep phenotype-genotype analysis of a comprehensive series of ganglioglioma (GG) with brain somatic alterations of the PTPN11/KRAS/NF1 genes compared to GG with common MAP-Kinase signaling pathway alterations, i.e., BRAFV600E. Seventy-two GG were submitted to whole exome sequencing and genotyping and 84 low grade epilepsy associated tumors (LEAT) to DNA-methylation analysis. In 28 tumours, both analyses were available from the same sample. Clinical data were retrieved from hospital files including disease onset, age at surgery, brain localization, and seizure outcome. A comprehensive histopathology staining panel was available in all cases. We identified eight GG with PTPN11 alterations, copy number variant (CNV) gains of chromosome 12, and the commonality of additional CNV gains in NF1, KRAS, FGFR4 and RHEB, as well as BRAFV600E alterations. Histopathology revealed an atypical glio-neuronal phenotype with subarachnoidal tumor spread and large, pleomorphic, and multinuclear cellular features. Only three out of eight patients with GG and PTPN11/KRAS/NF1 alterations were free of disabling-seizures 2 years after surgery (38% had Engel I). This was remarkably different from our series of GG with only BRAFV600E mutations (85% had Engel I). Unsupervised cluster analysis of DNA methylation arrays separated these tumours from well-established LEAT categories. Our data point to a subgroup of GG with cellular atypia in glial and neuronal cell components, adverse postsurgical outcome, and genetically characterized by complex alterations in PTPN11 and other RAS-/MAP-Kinase and/or mTOR signaling pathways. These findings need prospective validation in clinical practice as they argue for an adaptation of the WHO grading system in developmental, glio-neuronal tumors associated with early onset focal epilepsy.

Central nervous system involvement in individuals with RASopathies

Central nervous system (CNS) anomalies are common in individuals with RASopathies. While certain findings, including relative or absolute macrocephaly, are typical for most RASopathies, other findings are more common in certain conditions, with rare low-grade gliomas in Noonan syndrome (NS); Chiari 1 malformation and tethered cord in Costello syndrome (CS); and variable structural anomalies including heterotopia and hydrocephalus in cardio-facio-cutaneous syndrome (CFC). We performed a literature review and present aggregate data on the common and uncommon CNS manifestations in individuals with RASopathies. A gene-based approach to defining risk for specific abnormalities may be considered. However, limited information on the CNS findings of rare RASopathies, such as autosomal recessive LZTR1-related NS or PPP1CB-related NS with loose anagen hair (NSLH), is currently available. Thus, consideration of the RASopathies as a group of distinct syndromic conditions with shared underlying causes and overlapping clinical presentations remains relevant, and individuals with a RASopathy are at risk for many findings seen in these conditions.

RASopathy Cohort of Patients Enrolled in a Brazilian Reference Center for Rare Diseases: A Novel Familial LZTR1 Variant and Recurrent Mutations

Purpose

Noonan syndrome and related disorders are genetic conditions affecting 1:1000-2000 individuals. Variants causing hyperactivation of the RAS/MAPK pathway lead to phenotypic overlap between syndromes, in addition to an increased risk of pediatric tumors. DNA sequencing methods have been optimized to provide a molecular diagnosis for clinical and genetic heterogeneity conditions. This work aimed to investigate the genetic basis in RASopathy patients through Next Generation Sequencing in a Reference Center for Rare Diseases (IFF/Fiocruz) and implement the precision medicine at a public health institute in Brazil.

Patients and Methods

This study comprises 26 cases with clinical suspicion of RASopathies. Sanger sequencing was used to screen variants in exons usually affected in the PTPN11 and HRAS genes for cases with clinical features of Noonan and Costello syndrome, respectively. Posteriorly, negative and new cases with clinical suspicion of RASopathy were analyzed by clinical or whole-exome sequencing.

Results

Molecular analysis revealed recurrent variants and a novel LZTR1 missense variant: 24 unrelated individuals with pathogenic variants [PTPN11(11), NF1(2), SOS1(2), SHOC2(2), HRAS(1), BRAF(1), LZTR (1), RAF1(1), KRAS(1), RIT1(1), a patient with co-occurrence of PTPN11 and NF1 mutations (1)]; familial cases carrying a known pathogenic variant in PTPN11 (mother-two children), and a previously undescribed paternally inherited variant in LZTR1. The comparative modeling analysis of the novel LZTR1 variant p.Pro225Leu showed local and global changes in the secondary and tertiary structures, showing a decrease of about 1% in the β-sheet content. Furthermore, evolutionary conservation indicated that Pro225 is in a highly conserved region, as observed for known dominant pathogenic variants in this protein.

Conclusion

Bringing precision medicine through NGS towards congenital syndromes promotes a better understanding of complex clinical and/or undiagnosed cases. The National Policy for Rare Diseases in Brazil emphasizes the importance of incorporating and optimizing diagnostic methodologies in the Unified Brazilian Health System (SUS). Therefore, this work is an important step for the NGS inclusion in diagnostic genetic routine in the public health system.

How Genetics and Genomics Advances Are Rewriting Pediatric Cancer Research and Clinical Care

In the last two decades, thanks to the data that have been obtained from the Human Genome Project and the development of next-generation sequencing (NGS) technologies, research in oncology has produced extremely important results in understanding the genomic landscape of pediatric cancers, which are the main cause of death during childhood. NGS has provided significant advances in medicine by detecting germline and somatic driver variants that determine the development and progression of many types of cancers, allowing a distinction between hereditary and non-hereditary cancers, characterizing resistance mechanisms that are also related to alterations of the epigenetic apparatus, and quantifying the mutational burden of tumor cells. A combined approach of next-generation technologies allows us to investigate the numerous molecular features of the cancer cell and the effects of the environment on it, discovering and following the path of personalized therapy to defeat an "ancient" disease that has had victories and defeats. In this paper, we provide an overview of the results that have been obtained in the last decade from genomic studies that were carried out on pediatric cancer and their contribution to the more accurate and faster diagnosis in the stratification of patients and the development of new precision therapies.

Lateralized overgrowth with vascular malformation caused by a somatic PTPN11 pathogenic variant: another piece added to the puzzle of mosaic RASopathies

Lateralized/segmental overgrowth disorders (LOs) encompass a heterogeneous group of congenital conditions with excessive body tissue growth. Documented molecular alterations in LOs mostly consist of somatic variants in genes of the PI3KCA/AKT/mTOR pathway or of chromosome band 11p15.5 imprinted region anomalies. In some cases, somatic pathogenic variants in genes of the RAS/MAPK pathway have been reported. We present the first case of a somatic pathogenic variant (T507K) in PTPN11 causing a LO phenotype characterized by severe lateralized overgrowth, vascular proliferation, and cerebral astrocytoma. The T507K variant was detected in DNA from overgrown tissue in a leg with capillary malformation. The astrocytoma tissue showed a higher PTPN11 variant allele frequency. A pathogenic variant in FGFR1 was also found in tumor tissue, representing a second hit on the RAS/MAPK pathway. These findings indicate that RAS/MAPK cascade overactivation can cause mosaic overgrowth phenotypes resembling PIK3CA‐related overgrowth disorders (PROS) with cancer predisposition and are consistent with the hypothesis that RAS/MAPK hyperactivation can be involved in the pathogenesis of astrocytoma. This observation raises the issue of cancer predisposition in patients with RAS/MAPK pathway gene variants and expands genotype spectrum of LOs and the treatment options for similar cases through inhibition of the RAS/MAPK oversignaling.

Diencephalic Syndrome Due to Optic Pathway Gliomas in Pediatric Patients: An Italian Multicenter Study

Diencephalic syndrome (DS) is a rare pediatric condition associated with optic pathway gliomas (OPGs). Since they are slow-growing tumors, their diagnosis might be delayed, with consequences on long-term outcomes. We present a multicenter case series of nine children with DS associated with OPG, with the aim of providing relevant details about mortality and long-term sequelae. We retrospectively identified nine children (6 M) with DS (median age 14 months, range 3–26 months). Four patients had NF1-related OPGs. Children with NF1 were significantly older than sporadic cases (median (range) age in months: 21.2 (14–26) versus 10 (3–17); p = 0.015). Seven tumors were histologically confirmed as low-grade astrocytomas. All patients received upfront chemotherapy and nutritional support. Although no patient died, all of them experienced tumor progression within 5.67 years since diagnosis and were treated with several lines of chemotherapy and/or surgery. Long-term sequelae included visual, pituitary and neurological dysfunction. Despite an excellent overall survival, PFS rates are poor in OPGs with DS. These patients invariably present visual, neurological or endocrine sequelae. Therefore, functional outcomes and quality-of-life measures should be considered in prospective trials involving patients with OPGs, aiming to identify “high-risk” patients and to better individualize treatment.

Genetic conditions of short stature: A review of three classic examples

Noonan, Turner, and Prader-Willi syndromes are classical genetic disorders that are marked by short stature. Each disorder has been recognized for several decades and is backed by extensive published literature describing its features, genetic origins, and optimal treatment strategies. These disorders are accompanied by a multitude of comorbidities, including cardiovascular issues, endocrinopathies, and infertility. Diagnostic delays, syndrome-associated comorbidities, and inefficient communication among the members of a patient's health care team can affect a patient's well-being from birth through adulthood. Insufficient information is available to help patients and their multidisciplinary team of providers transition from pediatric to adult health care systems. The aim of this review is to summarize the clinical features and genetics associated with each syndrome, describe best practices for diagnosis and treatment, and emphasize the importance of multidisciplinary teams and appropriate care plans for the pediatric to adult health care transition.

Inside the Noonan "universe": Literature review on growth, GH/IGF axis and rhGH treatment: Facts and concerns

Noonan syndrome (NS) is a disorder characterized by a typical facial gestalt, congenital heart defects, variable cognitive deficits, skeletal defects, and short stature. NS is caused by germline pathogenic variants in genes coding proteins with a role in the RAS/mitogen-activated protein kinase signaling pathway, and it is typically associated with substantial genetic and clinical complexity and variability. Short stature is a cardinal feature in NS, with evidence indicating that growth hormone (GH) deficiency, partial GH insensitivity, and altered response to insulin-like growth factor I (IGF-1) are contributing events for growth failure in these patients. Decreased IGF-I, together with low/normal responses to GH pharmacological provocation tests, indicating a variable presence of GH deficiency/resistance, in particular in subjects with pathogenic PTPN11 variants, are frequently reported. Nonetheless, short- and long-term studies have demonstrated a consistent and significant increase in height velocity (HV) in NS children and adolescents treated with recombinant human GH (rhGH). While the overall experience with rhGH treatment in NS patients with short stature is reassuring, it is difficult to systematically compare published data due to heterogeneous protocols, potential enrolment bias, the small size of cohorts in many studies, different cohort selection criteria and varying durations of therapy. Furthermore, in most studies, the genetic information is lacking. NS is associated with a higher risk of benign and malignant proliferative disorders and hypertrophic cardiomyopathy, and rhGH treatment may further increase risk in these patients, especially as dosages vary widely. Herein we provide an updated review of aspects related to growth, altered function of the GH/IGF axis and cell response to GH/IGF stimulation, rhGH treatment and its possible adverse events. Given the clinical variability and genetic heterogeneity of NS, treatment with rhGH should be personalized and a conservative approach with judicious surveillance is recommended. Depending on the genotype, an individualized follow-up and close monitoring during rhGH treatments, also focusing on screening for neoplasms, should be considered.

Malignant intracerebral nerve sheath tumor in a patient with Noonan syndrome: illustrative case

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) within the neuroaxis are rare, usually arising from peripheral and cranial nerves. Even more scarce are cranial subclassifications of MPNSTs termed “malignant intracerebral nerve sheath tumors” (MINSTs). These tumors are aggressive, with a strong tendency for metastasis. With this presentation, alongside resistance to adjunctive therapy, complete excision is the mainstay of treatment, although it is often insufficient, resulting in a high rate of mortality.

OBSERVATIONS

The authors report the case of an adult patient with a history of Noonan syndrome (NS) presenting with slowly progressive right-sided hemiparesis and right-sided focal motor seizures. Despite initial imaging and histology suggesting a left frontal lobe high-grade intrinsic tumor typical of a glioblastoma, subsequent molecular analysis confirmed a diagnosis of MINST. The patient’s neurological condition improved after gross-total resection and adjuvant chemo-radiation; he remains on follow-up.

LESSONS

MINSTs are rare neoplasms with a poor prognosis; management options are limited, with surgery being the cornerstone of treatment. Reports on rare tumors such as this will increase awareness of this particular pathology and disclose clinical experience. In this case, the authors were unable to establish a definite cause-and-effect relation between NS and MINST. Nevertheless, it remains the first reported case in the literature.

Spinal cord glioblastoma multiforme in a patient with Noonan syndrome: A clinical report

INTRODUCTION

Currently, there are only 3 reported cases of central nervous system malignancies in patients with Noonan syndrome in the literature, all of which are intracranial pathologies. To our knowledge, there are no cases of spinal cord glioblastoma multiforme reported in the literature.

CASE DESCRIPTION

We describe the case of a 12-year-old girl with Noonan syndrome who presented with back pain and new onset neurological deficits and was found to have a spinal cord lesion. T10-L1 laminoplasty with safe maximal resection was done. Postoperative pathological analysis identified this lesion as a high-grade astrocytoma consistent with glioblastoma multiforme.

CONCLUSIONS

Spinal cord glioblastoma multiforme is a rare occurrence in the general population, particularly in a patient with an underlying diagnosis of Noonan syndrome. Patients with spinal cord tumors can present with a multitude of clinical signs and symptoms and treatment should not be delayed.