Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A Pathophysiological Approach to Spontaneous Orbital Meningoceles: Case Report and Systematic Review

BACKGROUND

Spontaneous orbital cephaloceles are a rare condition. The purpose of this study is to provide a description of a clinical case and to carry out a systematic literature review.

METHODS

A systematic review of the English literature published on the Pubmed, Scopus, and Web of Science databases was conducted, according to the PRISMA recommendations.

RESULTS

A 6-year-old patient was admitted for right otomastoiditis and thrombosis of the sigmoid and transverse sinuses, as well as the proximal portion of the internal jugular vein. Radiological examinations revealed a left orbital mass (22 × 14 mm) compatible with asymptomatic orbital meningocele (MC) herniated from the superior orbital fissure (SOF). The child underwent a right mastoidectomy. After the development of symptoms and signs of intracranial hypertension (ICH), endovascular thrombectomy and transverse sinus stenting were performed, with improvement of the clinical conditions and reduction of the orbital MC. The systematic literature review encompassed 29 publications on 43 patients with spontaneous orbital MC. In the majority of cases, surgery was the preferred treatment.

CONCLUSIONS

The present case report and systematic review highlight the importance of ICH investigation and a pathophysiological-oriented treatment approach. The experiences described in the literature are limited, making the collection of additional data paramount.

High-Grade Astrocytoma with Piloid Features: A Dual Institutional Review of Imaging Findings of a Novel Entity

High-grade astrocytoma with piloid features (HGAP) is a recently identified brain tumor characterized by a distinct DNA methylation profile. Predominantly located in the posterior fossa of adults, HGAP is notably prevalent in individuals with neurofibromatosis type 1. We present an image-centric review of HGAP and explore the association between HGAP and neurofibromatosis type 1. Data were collected from 8 HGAP patients treated at two tertiary care institutions between January 2020 and October 2023. Demographic details, clinical records, management, and tumor molecular profiles were analyzed. Tumor characteristics, including location and imaging features on MR imaging, were reviewed. Clinical or imaging features suggestive of neurofibromatosis 1 or the presence of NF1 gene alteration were documented. The mean age at presentation was 45.5 years (male/female = 5:3). Tumors were midline, localized in the posterior fossa (n = 4), diencephalic/thalamic (n = 2), and spinal cord (n = 2). HGAP lesions were T1 hypointense, T2-hyperintense, mostly without diffusion restriction, predominantly peripheral irregular enhancement with central necrosis (n = 3) followed by mixed heterogeneous enhancement (n = 2). Two NF1 mutation carriers showed signs of neurofibromatosis type 1 before HGAP diagnosis, with one diagnosed during HGAP evaluation, strengthening the HGAP-NF1 link, particularly in patients with posterior fossa masses. All tumors were IDH1 wild-type, often with ATRX, CDKN2A/B, and NF1 gene alteration. Six patients underwent surgical resection followed by adjuvant chemoradiation. Six patients were alive, and two died during the last follow-up. Histone H3 mutations were not detected in our cohort, such as the common H3K27M typically seen in diffuse midline gliomas, linked to aggressive clinical behavior and poor prognosis. HGAP lesions may involve the brain or spine and tend to be midline or paramedian in location. Underlying neurofibromatosis type 1 diagnosis or imaging findings are important diagnostic cues.

Epidemiology and Outcomes of Neurofibromatosis Type 1 (NF-1): Multicenter Tertiary Experience

Purpose

The aim of this manuscript was to assess the epidemiology and clinical features of Neurofibromatosis type 1 (NF-1) based on the newly published revised NF-1 diagnostic criteria and to evaluate complications of NF-1 including neurodevelopmental disorders.

Patients and methods

A retrospective cross-sectional observational study was conducted in the Ministry of National Guard Health Affairs (MNGHA) healthcare organization branches including four tertiary hospitals and 51 primary health care centers in different regions in Saudi Arabia. This study included all patients diagnosed with NF1 using the revised NIH diagnostic criteria published in 2021 that were registered at the electronic medical records (EMR) from 2015 to 2021.

Results

A total of 184 patients fulfilled the diagnostic criteria and were included in this study. The median age at diagnosis was 11 years (IQR: 4.00-20.25). The most encountered diagnostic criteria in this study were Café-au-lait macules (85.3%), and (42.9%) were found to have two or more neurofibromas with plexiform neurofibroma being the most common subtype (23.36%), approximately (36.4%) of the patient with optic pathway glioma. Nearby (26.6%) of the patients displayed different type of tumors. Iris Lisch nodules were presented in 36.4% of patients at a median age of 12 years (IQR: 9.0-21.8). Cardiovascular abnormality was encountered in 9.8% of the patients. Around 27.7% of the patients reported headache and 11.4% of the patient suffered from different type of epilepsy. Besides, 10.5% of the patients had intellectual disability, 33.8% suffered from communication disorders, and 4.9% patients had ADHD.

Conclusion

The results of this study will enable practitioners to adopt a more holistic approach and prioritize numerous attributes, which they can subsequently incorporate into their therapeutic methodologies. Furthermore, the identification of these attributes will facilitate an expeditious and accurate diagnosis. Hence, the implementation of intervention during its nascent phase may result in a more advantageous consequence.

Highly Active Relapsing-Remitting Multiple Sclerosis with Neurofibromatosis Type 1: Radiological Aspects and Therapeutic Challenges - Case Report

Introduction

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease which can rarely co-exist with neurofibromatosis 1 (NF1), a neurocutaneous inherited disorder that predisposes to oncogenesis. Patients who suffer from both conditions can be challenging cases for clinicians, as clinical symptoms and radiological findings may overlap, while MS immune-modifying treatments could further increase the risk of oncogenesis.

Case Presentation

In this study, we describe the case of a 27-year-old woman who presented with signs and symptoms of optic neuritis and was then diagnosed with both MS and NF1. As the patient continued to experience MS relapses despite initial interferon-beta treatment, she was subsequently switched to natalizumab and responded well.

Conclusion

This case illustrates how MRI lesion differentiation with the co-existence of MS and NF1 can be difficult due to overlaps in lesion characteristics, while treatment decisions can be challenging mainly due to scarce data on the oncogenic risk of MS immunomodulary therapies. Therefore, clinicians need to balance out the risk of malignancy development with the risk of progressive neurological disability when treating such patients.

Cerebral Vasculopathy in Children with Neurofibromatosis Type 1

Cerebrovascular abnormalities are a severe and often underrecognized complication of childhood neurofibromatosis type 1 (NF1). There are no prospective studies of cerebral vasculopathy in NF1; thus, the estimated frequency of vasculopathy varies between studies. The data is difficult to interpret due to the retrospective data collection and variability in whether imaging is done based on screening/surveillance or due to acute neurologic symptoms. The prevalent NF1-associated cerebral vasculopathy is moyamoya syndrome (MMS). Vascular changes can present without symptoms or with acute TIA or stroke-like symptoms or a range of progressive neurologic deficits. Advanced imaging may enhance sensitivity of neuroimaging in children. Medical and/or surgical interventions may prevent short- and long-term complications. Challenges for establishment of a screening protocol for cerebral vasculopathy in children with NF1 include the relatively large number of patients with NF1, the potential need for sedation to achieve quality imaging and the broad age range at time of detection for cerebral vascular changes. The goal of this review is to present the epidemiology, clinical presentation, imaging features and medical/surgical management of cerebral arteriopathies in children with NF1.

Hyperplasia of Arachnoid Trabecular Cells: A Hitherto Undescribed Lesion Observed in the Setting of Neurofibromatosis Type 1

Central nervous system manifestations, a variety of benign and malignant tumors as well as non-neoplastic abnormalities, are found in over 70% of neurofibromatosis type 1 (NF1) patients. Herein, we report hitherto undescribed space-occupying lesions in the setting of NF1. We aimed to clarify their characteristics, especially whether they represent neoplastic or non-neoplastic (hyperplastic) lesions. All 3 cases were preoperatively assessed as non-neoplastic; 2 and 1 cases were suspected to be arachnoid cysts and dilation of subarachnoid space, respectively. However, all lesions were revealed to be whitish jelly-like masses by operation, and the histology composed of spindle cells resembling arachnoid trabecular cells with moderate cellularity and cellular uniformity gave an impression that these lesions may be neoplastic. In contrast, electron microscopic analysis showed that the characteristics of these cells were compatible with those of normal arachnoid trabecular cells. Furthermore, whole-exome sequencing and array comparative genomic hybridization did not show any obvious alterations suggestive of their neoplastic nature. DNA methylation analysis demonstrated that these lesions were epigenetically distinct not only from meningiomas but also from normal healthy meninges. In conclusion, considering the clinicopathologic aspects of the present lesions and the results of the molecular analysis that failed to suggest their neoplastic nature, they may represent previously unrecognized rare hyperplasia of arachnoid trabecular cells, which may be associated with NF1.

Giant Tumefactive Perivascular Space: Advanced Fusion MR Imaging and Tractography Study-A Case Report and a Systematic Review

Perivascular spaces (PVSs) are small extensions of the subpial cerebrospinal space, pial-lined and interstitial fluid-filled. They surround small penetrating arteries, and veins, crossing the subarachnoid space to the brain tissue. Magnetic Resonance Imaging (MRI) shows a PVS as a round-shape or linear structure, isointense to the cerebrospinal fluid, and, if larger than 1.5 cm, they are known as giant/tumefactive PVSs (GTPVS) that may compress neighboring parenchymal/liquoral compartment. We report a rare asymptomatic case of GTPVS type 1 in a diabetic middle-aged patient, occasionally discovered. Our MRI study focuses on diffusion/tractography and fusion imaging: three-dimensional (3D) constructive interference in steady state (CISS) and time of fly (TOF) sequences. The advanced and fusion MR techniques help us to track brain fiber to assess brain tissue compression consequences and some PVS anatomic features as the perforating arteries inside them.

Evaluating Focal Areas of Signal Intensity (FASI) in Children with Neurofibromatosis Type-1 (NF1) Treated with Selumetinib on Pediatric Brain Tumor Consortium (PBTC)-029B

Background: Understanding the effect of selumetinib on FASI may help elucidate the biology, proliferative potential, and role in neurocognitive changes for these NF1-associated lesions. Methods: Patients with NF1-associated LGG and FASI treated with selumetinib on PBTC-029B were age-matched to untreated patients with NF1-associated FASI at Cincinnati Children’s Hospital Medical Center. Paired bidirectional measurements were compared over time using nonparametric tests. Results: Sixteen age-matched pairs were assessed (age range: 2.8–16.9 years, 60% male). Initial FASI burden was not different between groups (median range 138.7 cm2 [88.4–182.0] for the treated subjects vs. 121.6 cm2 [79.6—181.9] for the untreated subjects; p = 0.98). Over a mean follow-up of 18.9 (±5.9) months, the LGG size consistently decreased with treatment while no consistent change among the treated or untreated FASI size was seen. At the paired time points, the median treated LGG decreased significantly more than the treated FASI (−41.3% (LGG) versus −10.7% (FASI), p = 0.006). However, there was no difference in the median size change in the treated versus untreated FASI (−10.7% (treated FASI) versus −17.9% (untreated FASI), p = 0.08). Among the treated subjects, there was no correlation between the change in LGG and FASI (r = −0.04, p = 0.88). Conclusions: Treatment with selumetinib did not affect the overall FASI size in children with NF1 treated for progressive low-grade glioma.

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.

[Neurofibromatosis type 1 : From diagnosis to follow-up]

BACKGROUND

Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome and is one of the most common genetic diseases. It is therefore a condition encountered by radiologists in clinical routine. Since the variability of the clinical expression is very high and several organ systems are affected, we present a standardized diagnostic approach in this article.

METHODS

Evaluation of the literature on neurofibromatosis type 1 in the context of radiological examination methods.

RESULTS

In addition to the frequently known changes in the central and peripheral nervous system such as optic gliomas and plexiform neurofibromas, lesions from the orthopedic spectrum and vascular changes must also be included in the radiological diagnosis.

CONCLUSIONS

Due to the diversity of the clinical picture of NF1, it is reasonable to define an examination strategy which takes into account the needs of radiological routine and also reliably detects the most frequent and prognostically significant pathologies accompanying this disease. In this article, the current recommendations for diagnosis of neurofibromatosis-associated tumors and skeletal changes are summarized, and examination protocols and time intervals are suggested.

Severe High Cervical Cord Compression Due to Large Bilateral Neurofibromas in a Patient With Neurofibromatosis Type 1: A Case Report and Review of Literature

Spinal neurofibromas are rare benign lesions associated with neurofibromatosis Type 1. They can often cause compression on nerve roots and the spinal cord. In this rare case, there are bilateral large neurofibromas with severe cord compression presenting as progressive myelopathy. We illustrate the surgical management as well as post-operative care along with a detailed literature review of similar cases. To our knowledge, this is the first report, in English literature, of spinal neurofibroma with large size, bilateral high cervical cord compression.

Neurofibromatosis from Head to Toe: What the Radiologist Needs to Know

Neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) are autosomal dominant inherited neurocutaneous disorders or phakomatoses secondary to mutations in the NF1 and NF2 tumor suppressor genes, respectively. Although they share a common name, NF1 and NF2 are distinct disorders with a wide range of multisystem manifestations that include benign and malignant tumors. Imaging plays an essential role in diagnosis, surveillance, and management of individuals with NF1 and NF2. Therefore, it is crucial for radiologists to be familiar with the imaging features of NF1 and NF2 to allow prompt diagnosis and appropriate management. Key manifestations of NF1 include café-au-lait macules, axillary or inguinal freckling, neurofibromas or plexiform neurofibromas, optic pathway gliomas, Lisch nodules, and osseous lesions such as sphenoid dysplasia, all of which are considered diagnostic features of NF1. Other manifestations include focal areas of signal intensity in the brain, low-grade gliomas, interstitial lung disease, various abdominopelvic neoplasms, scoliosis, and vascular dysplasia. The various NF1-associated abdominopelvic neoplasms can be categorized by their cellular origin: neurogenic neoplasms, interstitial cells of Cajal neoplasms, neuroendocrine neoplasms, and embryonal neoplasms. Malignant peripheral nerve sheath tumors and intracranial tumors are the leading contributors to mortality in NF1. Classic manifestations of NF2 include schwannomas, meningiomas, and ependymomas. However, NF2 may have shared cutaneous manifestations with NF1. Lifelong multidisciplinary management is critical for patients with either disease. The authors highlight the genetics and molecular pathogenesis, clinical and pathologic features, imaging manifestations, and multidisciplinary management and surveillance of NF1 and NF2. Online supplemental material is available for this article. ^©RSNA, 2022.