Multiple meningiomas: differential involvement of the NF2 gene in children and adults

SMARCE1-related meningiomas: A clear example of cancer predisposing syndrome

We report the case of a 16-year-old girl presenting with spinal clear-cell multiple meningiomas (CCMs). In view of this presentation, we sequenced a bioinformatic panel of genes associated with susceptibility to meningioma, identifying a germline heterozygous variant inSMARCE1. Somatic DNA investigations in the CCM demonstrated the deletion of the wild-type allele (loss of heterozygosity, LOH), supporting the causative role of this variant. Family segregation study detected the SMARCE1 variant in the asymptomatic father and in the asymptomatic sister who, nevertheless, presents 2 spinal lesions. Germline heterozygous loss-of-function (LoF) variants in SMARCE1, encoding a protein of the chromatin-remodeling complex SWI/SNF, have been described in few familial cases of susceptibility to meningioma, in particular the CCM subtype. Our case confirms the role of NGS in investigating predisposing genes for meningiomas (multiple or recurrent), with specific regard to SMARCE1 in case of pediatric CCM. In addition to the age of onset, the presence of familial clustering or the coexistence of multiple synchronous meningiomas also supports the role of a genetic predisposition that deserves a molecular assessment. Additionally, given the incomplete penetrance, it is of great importance to follow a specific screening or follow-up program for symptomatic and asymptomatic carriers of pathogenic variants in SMARCE1.

Updated protocol for genetic testing, screening and clinical management of individuals at risk of NF2-related schwannomatosis

Genetic testing and management of individuals at risk for NF2-related schwannomatosis is complicated by the high rate of mosaicism resulting in a milder, later onset, more asymmetrical disease and the phenotypic overlap with the related schwannomatosis conditions. This updated protocol has been devised for the English NF2-related schwannomatosis service. It provides those affected with mosaic NF2-related schwannomatosis estimated risks of having an affected child; and management guidelines both for individuals at risk of NF2-related schwannomatosis, or with potential disease, due to having features that fall short of consensus diagnostic criteria. Risks of mosaicism and inferred transmission risks were derived from genetic testing of over 1000 individuals through the Manchester NF2 genetic testing service. This updated protocol, reflects the lower transmission risks now inferred in mosaic NF2-related schwannomatosis, informed by the greater sensitivity of Next Generation Sequencing in detecting low levels of mosaicism in blood, along with improved ability to analyse tumour DNA. Screening for features of NF2-related schwannomatosis is proposed until the risk of having the condition falls below a pragmatic threshold of 1%. Using these revised transmission figures, this threshold can now be reached at a younger age in many of those at risk, with earlier reassurance and discharge.

Ptosis, Visual Blurring, and Multiple Cranial Nerve Tumors: Do We Know the Culprit

Neurofibromatosis type 2 (NF2) is a monogenic condition caused by mutations in the NF2 gene. Examination of skin and eyes and parental screening play a key role in the diagnosis of pediatric NF2. We report a four-year-old boy, who presented sub-acutely with unilateral vision loss, ptosis and exotropia with a positive family history of NF2.

Epidemiological features of meningiomas: a single Brazilian center's experience with 993 cases

BACKGROUND

Meningiomas are the most frequent primary central nervous system (CNS) tumors. Their geographical and ethnic characteristics need to be known, in order to enable rational treatment.

OBJECTIVE

To investigate clinical and epidemiological aspects in a series of patients with meningiomas.

METHODS

Retrospective analysis on the demographic profile, location and histopathology of 993 patients with meningiomas (768 operated and 225 not operated).

RESULTS

Meningiomas represented 43.8% of the primary CNS tumors; 6.8% were multiple tumors (14.7% with neurofibromatosis 2) and 0.6% were radiation-induced tumors. The mean ages were 53.0 and 63.9 years for operated and non-operated patients and the female/male ratios were 3.2:1 and 6.3:1. Diagnosis was made later among females. The peak incidences were in the 6th and 7th decades respectively for operated and non-operated patients. The incidence was low at early ages and higher among patients aged 70+ years. The meningiomas were intracranial in 96.5% and most were WHO grade I (88.9%) and transitional. In the spinal canal (3.5%), they occurred mainly in the dorsal region (all grade I; mostly transitional). The racial distribution was 1.0% in Asian-Brazilians, 87% in Caucasians and 12% in African-Brazilians. 83.4% and 51.6% of the patients were estimated to be recurrence-free at 10 and 20 years, and the mortality rate was 3%.

CONCLUSIONS

Most of the demographic data were similar to what has been observed in other western centers. Differences were higher incidence of meningiomas, female and older predominance in non-operated patients, predominance in Caucasian, and higher association with neurofibromatosis 2.

Pathogenic noncoding variants in the neurofibromatosis and schwannomatosis predisposition genes

Neurofibromatosis type 1 (NF1), type 2 (NF2), and schwannomatosis are a group of autosomal dominant disorders that predispose to the development of nerve sheath tumors. Pathogenic variants (PVs) that cause NF1 and NF2 are located in the NF1 and NF2 loci, respectively. To date, most variants associated with schwannomatosis have been identified in the SMARCB1 and LZTR1 genes, and a missense variant in the DGCR8 gene was recently reported to predispose to schwannomas. In spite of the high detection rate for PVs in NF1 and NF2 (over 90% of non-mosaic germline variants can be identified by routine genetic screening) underlying PVs for a proportion of clinical cases remain undetected. A higher proportion of non-NF2 schwannomatosis cases have no detected PV, with PVs currently only identified in around 70%-86% of familial cases and 30%-40% of non-NF2 sporadic schwannomatosis cases. A number of variants of uncertain significance have been observed for each disorder, many of them located in noncoding, regulatory, or intergenic regions. Here we summarize noncoding variants in this group of genes and discuss their established or potential role in the pathogenesis of NF1, NF2, and schwannomatosis.

Current Understanding of Neurofibromatosis Type 1, 2, and Schwannomatosis

Neurofibromatosis (NF) is a neurocutaneous syndrome characterized by the development of tumors of the central or peripheral nervous system including the brain, spinal cord, organs, skin, and bones. There are three types of NF: NF1 accounting for 96% of all cases, NF2 in 3%, and schwannomatosis (SWN) in <1%. The NF1 gene is located on chromosome 17q11.2, which encodes for a tumor suppressor protein, neurofibromin, that functions as a negative regulator of Ras/MAPK and PI3K/mTOR signaling pathways. The NF2 gene is identified on chromosome 22q12, which encodes for merlin, a tumor suppressor protein related to ezrin-radixin-moesin that modulates the activity of PI3K/AKT, Raf/MEK/ERK, and mTOR signaling pathways. In contrast, molecular insights on the different forms of SWN remain unclear. Inactivating mutations in the tumor suppressor genes SMARCB1 and LZTR1 are considered responsible for a majority of cases. Recently, treatment strategies to target specific genetic or molecular events involved in their tumorigenesis are developed. This study discusses molecular pathways and related targeted therapies for NF1, NF2, and SWN and reviews recent clinical trials which involve NF patients.

COX2 expression is associated with proliferation and tumor extension in vestibular schwannoma but is not influenced by acetylsalicylic acid intake

Acetylsalicylic acid has been linked to a lower risk for different cancer types, presumably through its inhibitory effect on cyclooxygenase 2. This has also been investigated in vestibular schwannomas with promising results suggesting an antiproliferative effect and recently the intake has been recommended for vestibular schwannomas as a conservative treatment option. We constructed tissue microarrays from paraffin-embedded tissue samples of 1048 vestibular schwannomas and analyzed the expression of cyclooxygenase 2 and the proliferation marker MIB1 (Molecular Immunology Borstel) via immunohistochemistry together with clinical data (age, gender, tumor extension, prior radiotherapy, neurofibromatosis type 2, tumor recurrence, cyclooxygenase 2 responsive medication). Univariate analysis showed that cyclooxygenase 2 expression was increased with age, female gender, prior radiotherapy and larger tumor extension. MIB1 expression was also associated with higher cyclooxygenase 2 expression. Schwannomas of neurofibromatosis type 2 patients had lower cyclooxygenase 2 levels. Use of acetylsalicylic acid, non-steroidal anti-inflammatory drugs, glucocorticoids or other immunosuppressants did not show differences in cyclooxygenase 2 or MIB1 expression. Instead, cyclooxygenase 2 expression increases with tumor extension while MIB1 expression is not associated with tumor size. Overall, cyclooxygenase 2 expression is associated with proliferation but not influenced by regular intake of acetylsalicylic acid or other cyclooxygenase 2-responsive medications. Acetylsalicylic acid intake does not alter cyclooxygenase 2 expression and has no antiproliferative effect in vestibular.

Magnetic resonance imaging spectrum of spinal meningioma

PURPOSE

To evaluate magnetic resonance (MR) imaging findings of spinal meningioma and to determine the radiological subtypes based on the MR imaging findings and their respective clinical features.

MATERIAL AND METHODS

Data for 105 patients with surgically treated and histopathologically diagnosed spinal meningiomas at our hospital between May 1, 2003 and May 1, 2017 were evaluated in this study. Two radiologists reviewed the characteristics of spinal meningiomas on MR images and categorized the spinal meningiomas into subtypes based on MR imaging findings.

RESULTS

Most spinal meningiomas showed higher signal intensity than that of the spinal cord but lower than that of the subcutaneous fat on T2-weighted images (WI). 56 cases (54%) showed adjacent spinal cord signal changes. Meningiomas could be categorized according to MR imaging findings into type A: dural-based tumors with a homogeneous signal intensity and intense contrast enhancement (81 cases, 77%); type B: round or oval-shaped tumors with an internal hypointense portion on T2-weighted images (18 cases, 17%); type C: en plaque tumors (three cases, 3%); and type D: tumors with unusual findings and a heterogeneous appearance (three cases, 3%). All type C patients showed spinal cord signal changes.

CONCLUSIONS

Spinal meningioma showed slightly high signal intensity rather than high signal intensity on T2-weighted images. Spinal cord signal changes were present in more than half of the cases. Clinical differences were observed among the different MR imaging types.

[Hereditary tumor syndromes in neuropathology]

Neoplasms in the central (CNS) and peripheral nervous system (PNS) in hereditary tumor syndromes play an important role in the neuropathological diagnostics. The benign and malignant PNS and CNS tumors that occur in the frequent neurofibromatosis type 1 (NF1) and type 2 (NF2) often represent essential factors for the course of the disease in those affected. Furthermore, certain clinical constellations (e.g. bilateral schwannomas of the auditory nerve, schwannomas at a young age and multiple meningiomas) can be important indications for a previously undiagnosed hereditary tumor disease. Other tumors occur practically regularly in association with certain germline defects, e.g. subependymal giant cell astrocytoma (SEGA) in tuberous sclerosis and dysplastic gangliocytoma of the cerebellum in Cowden's syndrome and can be indications in the diagnostics for an extended genetic counselling. This is not only important because many germline defects are based on new mutations, but also for the now established targeted therapy of certain tumors, e.g. inhibition of the mammalian target of rapamycin (mTOR) signaling pathway using temsirolimus for SEGA. Furthermore, knowledge about the possible constellations of genetic mosaics in hereditary tumor syndromes with the resulting (incomplete) syndrome manifestations is useful. This review article summarizes the most important hereditary tumor syndromes with involvement of the PNS and CNS.

Neurofibromatosis Type 2

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder (incidence 1:33 000-40 000) characterized by formation of central nervous system tumors, due to mutation in the NF2 gene on chromosome 22q12. Vestibular schwannomas are the hallmark lesion, affecting 95% of individuals and typically occur bilaterally. Schwannomas commonly occur on other nerves intracranially and in the spinal compartment, along with meningiomas, ependymomas, and gliomas. Although histologically benign, tumors are associated with significant morbidity due to multiple problems including hearing and vision loss, gait abnormalities, paralysis, pain, and seizures. Risk of early mortality from brainstem compression and other complications is significant. Severity of disease is higher when NF2 presents during childhood. Children have a more variable presentation, which can be associated with significant delays in recognition of the condition. Careful examination of the skin and eyes can identify important clinical signs of NF2 during childhood, allowing timely initiation of disease-specific surveillance and treatment. Monitoring for complications comprises clinical evaluation, along with functional testing including audiology and serial neuroimaging, which together inform decisions regarding treatment. Evidence for disease-specific medical treatment options is increasing, nevertheless most patients will benefit from multimodal treatment including surgery during their lifetime. Patient enrolment in international natural history and treatment trials offers the best opportunity to accelerate our understanding of the complications and optimal treatment of NF2, with a view to improving outcomes for all affected individuals.

Multiple meningiomas: Clinical, radiological, surgical, and pathological findings with outcome in four cats

The present report describes the clinical signs, magnetic resonance imaging (MRI) findings, surgical procedure, pathological findings and follow-up in four cats with multiple meningiomas; three castrated male and one spayed female domestic shorthair indoor cats, ranging in age from 11 to 14 years. In three of four cats, clinical signs at presentation were suggestive of a focal lesion. Three cats had two meningiomas and one had four meningiomas. Most of the tumours were supratentorial, one arose from the tentorium and one was infratentorial. The duration of presenting signs before surgery ranged from 10 days to 11 months. Postoperative MRI revealed complete gross tumour removal in three cases. In one cat with two cranial fossa meningiomas, subtotal excision with a small basal remnant (2×2 mm) of the ventral part of one meningioma lying on the floor of the skull, was observed. Based on histopathological architecture, six tumours revealed features of a transitional subtype meningioma, and four of a meningotheliomatous meningioma. In each cat, the multiple meningiomas were all assigned to the same histopathological group. The preoperative presenting signs had resolved by the follow-up examinations 4 weeks after surgery in two cats. Long-term follow-up evaluation revealed that surgically-induced or exacerbated neurological deficits in two cats had completely or almost completely resolved within 8 weeks of surgery. All patients are still alive 12 to 21 months after surgery and no clinical signs of recurrence could be detected at that time.

Multiple spinal and cranial meningiomas: A case report and review of literature

Though meningiomas are common neoplasms of the nervous system, the occurrence of multiple meningiomas in different neuraxial compartments is rather rare. We report a case of a 62-year-old female who presented with spastic paraparesis in both lower limbs, and was found to have multiple homogenously enhancing tumors of dorsolumbar spine. Cranial magnetic resonance imaging (MRI) revealed multiple bilateral supratentorial meningiomas. She underwent multiple level laminectomy and total removal of spinal tumors after which power improved in both lower limbs. Histopathology revealed psammomatous meningiomas. Only around 19 cases of multiple cranial and spinal meningiomas have been reported, of which, only five cases have more than one spinal meningioma. The implication of the incidence of such multiple meningiomas in the same patient with relevance to investigations and decision making are discussed along with a brief review of literature of cases with multiple spinal and cranial meningiomas.

Germline and somatic mutations in meningiomas

Meningiomas arise from the arachnoid layer of the meninges that surround the brain and spine. They account for over one third of all primary central nervous system tumors in adults and confer a significant risk of location-dependent morbidity due to compression or displacement. A significant increase in risk of meningiomas is associated with neurofibromatosis type 2 (NF2) disease through mutation of the NF2 gene. In addition, approximately 5% of individuals with schwannomatosis disease develop meningiomas, through mutation of the SWI/SNF chromatin remodeling complex subunit, SMARCB1. Recently, a second SWI/SNF complex subunit, SMARCE1, was identified as a cause of clear cell meningiomas, indicating a wider role for this complex in meningioma disease. The sonic hedgehog (SHH)-GLI1 signaling pathway gene, SUFU, has also been identified as the cause of hereditary multiple meningiomas in a large Finnish family. The recent identification of somatic mutations in components of the SHH-GLI1 and AKT1-MTOR signaling pathways indicates the potential for cross talk of these pathways in the development of meningiomas. This review describes the known meningioma predisposition genes and their links to the recently identified somatic mutations.

Multiple faces of children and juvenile meningiomas: a report of single-center experience and review of literature

OBJECTIVE

Pediatric meningiomas are extremely rare tumors often associated with various medical conditions. This report is an attempt to analyze the clinical behavior, pathological presentation and recommended management of both isolated and neurofibromatosis type 2 (NF2) related pediatric meningiomas in comparison to their adult counterparts.

METHODS

The investigated group consisted of three male and six female patients suffering from meningiomas of the central nervous system, who were hospitalized at our department in years 2001-2012.

RESULTS

In our group three children were diagnosed with NF2. Two were released with a suspicion of that disease. Three patients had multiple meningiomas at the first presentation. The most common manifestation were focal neurological deficits (47%). Meningiomas were mostly located at the brain convexity (29%). Histological examination revealed the domination of fibrous type in our group (29%). Apart from surgical management a preoperative embolization of the tumors' vessels was implemented in two children. Another three children underwent postoperative radiotherapy (RTh), one received a chemotherapy (ChTh).

CONCLUSION

Meningiomas in children differ from their counterparts in adults. Due to common coexistence of pediatric meningiomas and neurofibromatosis type 2, this group of patients should be taken under strict control, because of high risk of tumor recurrence.

Prognostic value and management of spinal tumors in neurofibromatosis type 2 patients

PURPOSE

Neurofibromatosis type 2 (NF2) is a well-studied disease. Although spinal tumors are frequent, many issues concerning their prognosis and management still have to be clarified. The authors studied the clinical impact and radiological progression of spinal tumors in patients with NF2 to determine their prognostic value.

METHODS

A total of 80 NF2 patients were followed in the Lille University Hospital between 1987 and 2011. Clinical, radiological and genetic data were retrospectively recorded and analyzed. Patients underwent annual cranial and spinal MRI. Both the location and size of each tumor were reported. The diagnosis of NF2 was confirmed either because the patient met the Manchester criteria or by the presence of genetic mutation.

RESULTS

The mean follow-up period was 8.8 years (range 1 to 24 years; SD: ±0.8), and the mean age at diagnosis was 27.2 years (range 6 to 73 years; SD: ±1.7). Among all patients, 48 harbored spinal tumors. Twenty of them were symptomatic, and 21 were operated on. Patients with spinal tumors had a lower age at diagnosis (p = 0.02), a higher number of intracranial meningiomas (p = 0.028) and schwannomas (p = 0.03), and more nonsense and frameshift mutations (p = 0.04).

CONCLUSION

Spinal tumors are common in NF2, and all patients should be regularly monitored by spinal MRI. The presence of spinal tumors seems to be a factor indicating poor prognosis. Clinical and radiological monitoring of spinal tumors could lead to early treatment both when clinical symptoms are present and in case of proven radiological evolution, maintaining a favorable functional prognosis as long as possible.

Molecular and phenotypic characterization of ring chromosome 22 in two unrelated patients

We report on the cytogenetic and molecular characterization of a constitutional de novo ring chromosome 22 (r(22)) in 2 unrelated patients with emphasis on different hypotheses proposed to explain the phenotypic variability characterizing this genomic disorder. In both patients, molecular investigations using FISH and array-CGH techniques revealed a 22q terminal deletion involving the 22q13.33 critical region. The size of the deletion was estimated to at least 1.35 Mb in the first proband and to only 300 kb in the second. They both exhibited the major features of r(22) syndrome, but the first patient was more profoundly affected. He had a more severe phenotype, further complicated by behavioral anomalies, autistic-like features with abnormal EEG pattern and brain MRI profile. Haploinsufficiency of the SHANK3 gene, lying in the minimal critical region, is nowadays considered as responsible for most neurobehavioral anomalies. Nevertheless, phenotypic severity and occurrence of additional features in the first patient suggest a potential involvement of one or more specific gene(s) located proximally to SHANK3 (as PLXNB2, PANX2, ALG12 or MLC1), acting either independently of it or by regulating or promoting its expression and thus disrupting its function when deleted.

Clinicopathologic assay of 15 tumor resections in a family with neurofibromatosis type 2

The objective of this study is the management of multiple family members with multiple neurofibromatosis type 2 (NF2) related tumors of the skull base that can be challenging, on purely technical, decision-making, and ethical levels. These issues are addressed in this manuscript based on an experience treating an unique large family with NF2. A retrospective chart review was performed, reviewing clinical, radiological, surgical, and pathological data. A unique family of 17 siblings, whose father was the proband as a sporadic mutation is reported. Over a 4-month period, five of eight affected siblings underwent 12 procedures for resection of 15 different NF2-related tumors. This single family experience of NF2-related skull base tumors underscores the importance of preservation of function and quality of life as the major determinants of treatment success.

Pediatric meningiomas: a single-center experience with 15 consecutive cases and review of the literature

OBJECTIVE

The goal of this study was to determine the epidemiology, clinical presentation, associated factors, pathological features, and treatment outcome of pediatric meningiomas in a single-center institution.

METHODS

Clinical data of 15 patients under 18 years of age operated on for meningiomas from January 1994 to December 2010 were reviewed.

RESULTS

The study group included nine males and six females (mean age of 13 years at surgery). The most common symptoms at presentation were headaches in 6 out of 15 (40 %), raised intracranial pressure in 3 out of 15 (20 %), and seizures in 3 out of 15 (20 %). Sole operated tumors were found in 12 out of 15 (80 %), whose location is as follows: parasagittal in 4 out of 12 (33.3 %), 2 in the convexity (16.6 %), 2 at the skull base (16.6 %), and 4 in other sites (33.3 %). Six children presented with radiation-induced (RT) meningiomas and five had evidence of neurofibromatosis type 2 (NF2). Three patients had multiple meningiomas (all of them had NF2). Simpson's grade I excision was achieved in 12 out of 15 (80 %). On histopathology, 11 out of 15 (73.3 %) were grade I and 4 out of 15 (26.6 %) were grade II (all of them atypical). Five tumors (33.3 %) recurred, four of which had RT or NF2. During the mean follow-up period of 5 years, 12 out of 15 (80 %) had a good outcome (GOS=5).

CONCLUSIONS

Childhood meningiomas are uncommon lesions with a slight male predominance. Absence of large series with long follow-up precludes any definite conclusions on the clinical course and outcome of these tumors. Associated factors (such as RT and NF2), location, and extent of excision appear to be more important than histopathological grade in predicting outcome.

Genetic testing and screening of individuals at risk of NF2

Genetic testing and management of the at-risk individual for neurofibromatosis type 2 (NF2) is complicated by the well-documented risk of mosaicism that causes a milder later onset more asymmetrical disease course. Risks of NF2 were derived from genetic testing of over 1000 individuals through the Manchester NF2-testing service. Individuals are at risk of NF2 or have 'potential' NF2 if they have features of the disease that fall short of diagnostic criteria or are the first-degree relative of someone with NF2 or suspected NF2. The present protocol devised for the Nationally Commissioned Group (NCG) NF2 service in England addresses the risks, genetic testing and screening protocol for individuals at risk of NF2. Screening with cranial magnetic resonance imaging is advised until the risk of NF2 falls below a pragmatic threshold of 1%. Multiple case scenarios are shown to illustrate how to use the protocol.

Magnetic resonance imaging features of meningiomas in children and young adults: a retrospective analysis

OBJECTIVES

Meningiomas are rare in children and, unlike in adults, they have male predominance, unusual locations, cystic components and poorer clinical outcomes. The aims of our study were to: a) evaluate the MRI features of pediatric meningiomas; b) correlate ADC values of meningiomas with clinical and histopathological types; and c) correlate peritumoral edema with size and histopathological type of tumor.

PATIENTS AND METHODS

Radiological data from 24 patients (mean age: 14.3 years) with an imaging or histopathological diagnosis of meningioma, and presurgical MRI between 1995 and 2009 from two medical institutions, were reviewed. Meningiomas were clinically classified as spontaneously arising meningiomas (SAM), NF2-associated meningiomas (NF2-M) and radiation-induced meningiomas (RIM) and, histopathologically, according to the WHO classification system. The main MRI signal characteristics and enhancement were evaluated. ADC values were compared with histopathological type and clinical group. Tumor size and peritumoral edema were also assessed.

RESULTS

Thirty-four meningiomas (eight SAM, 13 NF2-M, 13 RIM) in 24 patients (12 male, 12 female) were evaluated. Unusual locations were frequently seen in SAM, including cases of intraventricular and intraparenchymal meningiomas. SAM were also always larger than either RIM or NF2-M. Cystic components were only found in SAM, and were not associated with high-grade tumors (WHO II and III). Mean ADC values were significantly different between SAM and NF2-M, but were not associated with histopathological type. Peritumoral edema correlated with tumor size, but did not differ significantly according to clinical group.

CONCLUSION

Pediatric SAM have unusual locations, larger size and cystic components, and are diagnosed at a younger age than NF2-M and RIM. NF2-M can have unusual locations such as, in particular, the craniocervical junction. Tumor ADC values did not help to predict tumor grade or clinical type. Peritumoral edema correlated with tumor size, but not with clinical group or histopathological grade.

Meningiomas and neurofibromatosis

Neurofibromatosis type 2 (NF2) is a rare genetic disorder predisposing to multiple benign tumors of the nervous system. Meningiomas occur in about half of NF2 patients, and are often multiple. Patients harboring seemingly isolated multiple meningiomas should be investigated to diagnose NF2 by careful familial history collection, detailed clinical examination (skin lesions and slit lamp examination of the lens), audiovestibular testing, and fine cranio-spinal Magnetic Resonance Imaging. Somatic mosaicism is frequent in NF2 and may explain a mild phenotype as, e.g. isolated multiple meningiomas. Neurofibromatosis type 1 is not associated with an increased risk of meningioma. Whether meningiomas are part of the schwannomatosis tumor phenotype or not remains debated. Meningiomas in NF2 patients are associated with a higher risk of mortality, and their treatment is challenging, but data about natural history of meningiomas in NF2 patients in the literature are sparse. Thus, knowledge of tumor behavior is essential in slow growing tumors like meningiomas, to balance the risk of treatment against the natural history of the disease, and to evaluate the efficiency of alternative therapeutics (radiation therapy or new drugs).

Neurofibromatosis 2 [Bilateral acoustic neurofibromatosis, central neurofibromatosis, NF2, neurofibromatosis type II]

Neurofibromatosis 2 is a dominantly inherited tumor predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. Affected individuals inevitably develop schwannomas typically affecting both vestibular nerves leading to deafness. Rehabilitation with brainstem implants is improving this outcome. Schwannomas also occur on other cranial nerves, on spinal nerve roots, and on peripheral nerves. Meningiomas and ependymomas are other tumor features. In excess of 50% of patients represent new mutations and as many as one third are mosaic for the underlying disease causing mutation. Although truncating mutations (nonsense and frameshifts) are the most frequent germline event and cause the most severe disease, single and multiple exon deletions are common. A strategy for detection of the latter is vital for a sensitive analysis. NF2 represents a difficult management problem with most patients facing substantial morbidity and reduced life expectancy. Surgery remains the focus of current management, although watchful waiting and occasionally radiation treatment have a role. In the future, the development of tailored drug therapies aimed at the genetic level are likely to provide huge improvements for this devastating, life limiting condition.

Schwannomatosis associated with multiple meningiomas due to a familial SMARCB1 mutation

Schwannomatosis (MIM 162091) is a condition predisposing to the development of central and peripheral schwannomas; most cases are sporadic without a clear family history but a few families with a clear autosomal dominant pattern of transmission have been described. Germline mutations in SMARCB1 are associated with schwannomatosis. We report a family with multiple schwannomas and meningiomas. A SMARCB1 germline mutation in exon 1 was identified. The mutation, c.92A>T (p.Glu31Val), occurs in a highly conserved amino acid in the SMARCB1 protein. In addition, in silico analysis demonstrated that the mutation disrupts the donor consensus sequence of exon 1. RNA studies verified the absence of mRNA transcribed by the mutant allele. This is the first report of a SMARCB1 germline mutation in a family with schwannomatosis characterized by the development of multiple meningiomas.

Neurofibromatosis type 2

Neurofibromatosis type 2 is an autosomal-dominant multiple neoplasia syndrome that results from mutations in the NF2 tumour suppressor gene located on chromosome 22q. It has a frequency of one in 25,000 livebirths and nearly 100% penetrance by 60 years of age. Half of patients inherit a germline mutation from an affected parent and the remainder acquire a de novo mutation for neurofibromatosis type 2. Patients develop nervous system tumours (schwannomas, meningiomas, ependymomas, astrocytomas, and neurofibromas), peripheral neuropathy, ophthalmological lesions (cataracts, epiretinal membranes, and retinal hamartomas), and cutaneous lesions (skin tumours). Optimum treatment is multidisciplinary because of the complexities associated with management of the multiple, progressive, and protean lesions associated with the disorder. We review the molecular pathogenesis, genetics, clinical findings, and management strategies for neurofibromatosis type 2.

Somatic TP53 mutation mosaicism in a patient with Li-Fraumeni syndrome

We present a girl who developed adrenocortical adenoma at the age of 1 year and osteosarcoma at the age of 5 years. There was no history of cancer in her parents and their relatives. However, both tumors were typical for the Li-Fraumeni syndrome (LFS), and the patient met criteria for germline TP53 mutation testing. A mutation in codon 282 (Arg282Trp) was identified in her blood lymphocyte genomic DNA. The substitution was found in neither of her parents, which indicated a possibility of a de novo mutation. Unexpectedly, sequencing of the DNA of the patient repeatedly showed allelic imbalance in favor of the normal allele. This observation prompted us to investigate the putative somatic mosaicism in the patient consisting of normal cells and cells heterozygous for the mutation. The imbalance was also examined in two other non-invasively sampled tissues, buccal cells, and cells from the urine sediment, and sequencing was confirmed with two other independent methods. While the findings in blood and the urine sediment were similar, in buccal cells both alleles were present in equal amounts. The allele ratio in lymphocytes was consistent with a mosaic where about 2/3 of cells carried two normal alleles and only 1/3 was heterozygous for the mutation. Despite the mosaicism the girl developed two early childhood tumors of mesodermal origin, and her phenotype was thus not milder than that of other germline TP53 mutation carriers. To our knowledge this is the first description of somatic mosaicism for a de novo TP53 mutation in LFS.

Multiple intracranial meningiomas: diagnosis, biological behavior and treatment

Multiple intracranial meningiomas (MIM) are a rare pathology when not associated with neurofibromatosis. The prevalence rate of those tumors varied from 2.3 to 8.9% of all intracranial meningiomas.

OBJECTIVE

To present, analyze and discuss the cases of seven patients diagnosed with multiple intracranial meningiomas, describing their clinical and histological characteristics, as well as their biological behavior.

METHOD

The patients records, surgical descriptions, imaging studies and the histopathological exams were retrospectively reviewed. This is the largest series of MIM publisted in Brazil.

RESULTS

This sample consists of five women and two men. The age varied from 42 to 84 (average 53.8). Twenty-two meningiomas were identified and varied from 1.5 to 192 cm(3), with an 62.8 cm(3) average volume. The number of procedures varied from 1 to 5 per patient. No surgical death occurred in this series.

CONCLUSION

Despite the multiplicity of tumors, number of recurrences, the new tumors, repeated operations and re-operations, radiotherapy and a number of postoperative complications, the patients experienced a long survival in conjunction with a fairly good quality of life.

[Phacomatosis and genetically determined tumors: the transition from childhood to adulthood]

Phacomatoses, or neurocutaneous disorders, are a group of congenital and hereditary diseases characterized by developmental lesions of the neuroectoderm, leading to pathologies affecting the skin and the central nervous system. There is a wide range of pathologies affecting individuals at different moments of life. The genetics is variable: while neurofibromatosis 1 and 2, tuberous sclerosis and von Hippel-Lindau disease are all inherited as autosomal dominant traits, Sturge-Weber syndrome is sporadic. Other neurocutaneous disorders can be inherited as autosomal recessive traits (i.e., ataxia-telangiectasia), X-linked (i.e., incontinentia pigmenti) or explained by mosaicism (i.e., hypomelanosis of Ito, McCune-Albright syndrome). In this review, we discuss the major types of neurocutaneous disorders most frequently encountered by the neurosurgeon and followed beyond childhood. They include neurofibromatosis types 1 and 2, tuberous sclerosis, Sturge-Weber syndrome and von Hippel-Lindau disease. In each case, a review of the literature, including diagnosis, genetics and treatment will be presented. The lifespan of the disease with the implications for neurosurgeons will be emphasized. A review of cases, including both pediatric and adult patients, seen in neurosurgical practices in the Lille, France and Lausanne, Switzerland hospitals between 1961 and 2007 is presented to illustrate the pathologies seen in different age-groups. Because the genes mutated in most phacomatoses are involved in development and are activated following a timed schedule, the phenotype of these diseases evolves with age. The implication of the neurosurgeon varies depending on the patient's age and pathology. While neurosurgeons tend to see pediatric patients affected with neurofibromatosis type 1, tuberous sclerosis and Sturge-Weber syndrome, there will be a majority of adult patients with von Hippel-Lindau disease or neurofibromatosis type 2.

[Neurofibromatosis type 2]

INTRODUCTION

Neurofibromatosis 2 (NF2) is a rare autosomal dominant disease whose hallmark is the development of bilateral vestibular schwannomas.

STATE OF THE ART

Other features of NF2 include schwannomas, meningiomas, ependymomas, localized along the central nervous system, schwannomas of the peripheral nerves, cutaneous and ophthalmological manifestations. NF2 can be diagnosed in patients without bilateral vestibular schwannoma with sets of diagnostic criteria. Disease phenotype is variable among patients. Main negative prognostic factors are a young age at onset of symptoms and a high number of tumors at diagnosis. NF2 tumor suppressor gene encodes Merlin/Schwannomin, and is also involved in most sporadic schwannomas and meningiomas. Its functions remains largely unknown.

PERSPECTIVES AND CONCLUSIONS

Treatment and follow of NF2 patients up require oto-neurosurgical teams experienced in NF2. Yearly and life time surveillance is mandatory. A clinical screening protocol is suggested. Classically, only symptomatic lesions are to be treated. Some authors advocate an early proactive strategy against vestibular schwannoma in order to preserve hearing. When a treatment is advisable, surgery remains the treatment of choice for tumors. Auditory brainstem implant must be taken into account in hearing rehabilitation.

Mosaicism in neurofibromatosis type 2: an update of risk based on uni/bilaterality of vestibular schwannoma at presentation and sensitive mutation analysis including multiple ligation-dependent probe amplification

BACKGROUND

Neurofibromatosis type 2 (NF2) is almost unique among inherited disorders in the frequency of mosaicism in the first affected generation. However, the implications of this on transmission risks have not been fully elucidated.

METHODS

The expanded database of 460 families with NF2 and 704 affected individuals was analysed for mosaicism and transmission risks to offspring.

RESULTS

64 mosaic patients, with a projected mosaicism rate of 33% for sporadic classical NF2 with bilateral vestibular schwannoma at presentation and 60% for those presenting unilaterally, were identified. Offspring risks can be radically reduced on the basis of a sensitive mutation analysis of blood DNA including multiple ligation-dependent probe amplification (MLPA, which detects 15% of all mutations), but even MLPA cannot detect high levels of mosaicism.

CONCLUSION

The chances of mosaicism in NF2 and the resultant risks of transmission of the mutation to offspring in a number of different clinical situations have been further delineated. The use of MLPA in this large NF2 series is also reported for the first time.

Mutational spectrum of the NF2 gene: a meta-analysis of 12 years of research and diagnostic laboratory findings

The NF2 tumor suppressor gene on chromosome 22 is a member of the protein 4.1 family of cytoskeletal elements. A number of single- and multiple-tumor phenotypes have been linked to alterations of NF2 since its characterization in 1993. We present a meta-analysis of 967 constitutional and somatic NF2 alterations from 93 published reports, along with 59 additional unpublished events identified in our laboratory and 115 alterations identified in clinical samples submitted to the Massachusetts General Hospital (MGH) Neurogenetics DNA Diagnostic Laboratory. In total, these sources defined 1,070 small genetic changes detected primarily by exon scanning, 42 intragenic changes of one whole exon or larger, and 29 whole gene deletions and gross chromosomal rearrangements. Constitutional single-exon events (N=422) were significantly more likely to be nonsense or splice site changes than somatic events (N=533), which favored frameshift changes (chi(2) test; P<0.001). Somatic events also differed markedly between tumors of different pathology, most significantly in the tendency of somatic events in meningiomas to lie within the 5' FERM domain of the transcript (Fisher's exact test; P<0.01 in comparison to schwannomas) with a complete absence of mutations in exons 14 and 15. There was no statistically significant difference in mutation type or exon distribution between published constitutional events and those found by the clinical laboratory. Less than 10% of all published and unpublished small alterations are nontruncating (N=63) and these changes are clustered in exons 2 and 3, suggesting that this region may be especially crucial to tumor suppressor activity in the protein.

Comprehensive genetic and epigenetic analysis of sporadic meningioma for macro-mutations on 22q and micro-mutations within the NF2 locus

BACKGROUND

Meningiomas are the most common intracranial neoplasias, representing a clinically and histopathologically heterogeneous group of tumors. The neurofibromatosis type 2 (NF2) tumor suppressor is the only gene known to be frequently involved in early development of meningiomas. The objective of this study was to identify genetic and/or epigenetic factors contributing to the development of these tumors. A large set of sporadic meningiomas were analyzed for presence of 22q macro-mutations using array-CGH in order to identify tumors carrying gene dosage aberrations not encompassing NF2. The NF2 locus was also comprehensively studied for point mutations within coding and conserved non-coding sequences. Furthermore, CpG methylation within the NF2 promoter region was thoroughly analyzed.

RESULTS

Monosomy 22 was the predominant finding, detected in 47% of meningiomas. Thirteen percent of the tumors contained interstitial/terminal deletions and gains, present singly or in combinations. We defined at least two minimal overlapping regions outside the NF2 locus that are small enough (approximately 550 kb and approximately 250 kb) to allow analysis of a limited number of candidate genes. Bialleinactivationo the NF2 gne was detected in 36% of meningiomas. Among the monosomy 22 cases, no additional NF2 mutations could be identified in 35% (17 out of 49) of tumors. Furthermore, the majority of tumors (9 out of 12) with interstitial/terminal deletions did not have any detectable NF2 mutations. Methylation within the NF2 promoter region was only identified at a single CpG site in one tumor sample.

CONCLUSION

We confirmed previous findings of pronounced differences in mutation frequency between different histopathological subtypes. There is a higher frequency of biallelic NF2 inactivation in fibroblastic (52%) compared to meningothelial (18%) tumors. The presence of macro-mutations on 22q also shows marked differences between fibroblastic (86%) and meningothelial (39%) subtypes. Thus, inactivation of NF2, often combined with the presence of macro-mutation on 22q, is likely not as important for the development of the meningothelial subtype, as opposed to the fibroblastic form. Analysis of 40 CpG sites distributed within 750 bp of the promoter region suggests that NF2 promoter methylation does not play a major role in meningioma development.

Atypical imaging appearances of intracranial meningiomas

Meningiomas are the commonest primary, non-glial intracranial tumours. The diagnosis is often correctly predicted from characteristic imaging appearances. This paper presents some examples of atypical imaging appearances that may cause diagnostic confusion.