Molecular analysis of the NF2 tumor-suppressor gene in schwannomatosis

Managing Multiple Schwannomatosis of Vagus and Hypoglossal Nerves: The Unanticipated Complications

Schwannomas are rare benign tumours of the nerve sheath. Extracranial schwannomas are usually found solitary, in the absence of other features of neurofibromatosis. The non NF1/2 multiple schwannomas are collectively described as the clinical scenario called schwannomatosis. We present a rare case of two extracranial schwannomas involving vagus and hypoglossal nerves in a 22-year-old female along with an unusual surgical complication of CSF leak presenting as post-op neck mass and a review of previously reported similar cases. A thorough literature search using the MeSH terms-'schwannomatosis' or 'Multiple Schwannoma' and 'Vagal Schwannoma' and 'Hypoglossal Schwannoma', was conducted using online databases and augmentated by hand search. A total of 13 reported cases were found and reviewed. Of the 14 cases described from review of literature and our case, 50% had involvement of vagus nerve as one of the components. 12.5% had hypoglossal and cervical sympathetic plexus involvement each. All patients underwent surgical excision. Half of the patients suffered intraoperative nerve sacrifice with resultant severe functional deficits like vocal cord paralysis, Horners syndrome, hypoglossal palsy, facial palsy and eleventh nerve palsy. In our case, there was un-unusual complication of CSF leak presenting as a cervical neck mass. Multiple extracranial head and neck schwannomas are rare and their management is fraught with several complications. Decision to operate is often perplexing. However, early planned surgical excision and preservation of nerve of origin minimizes the impact on quality of life postoperatively.

Mosaicism in Tumor Suppressor Gene Syndromes: Prevalence, Diagnostic Strategies, and Transmission Risk

A mosaic state arises when pathogenic variants are acquired in certain cell lineages during postzygotic development, and mosaic individuals may present with a generalized or localized phenotype. Here, we review the current state of knowledge regarding mosaicism for eight common tumor suppressor genes-NF1, NF2, TSC1, TSC2, PTEN, VHL, RB1, and TP53-and their related genetic syndromes/entities. We compare and discuss approaches for comprehensive diagnostic genetic testing, the spectrum of variant allele frequency, and disease severity. We also review affected individuals who have no mutation identified after conventional genetic analysis, as well as genotype-phenotype correlations and transmission risk for each tumor suppressor gene in full heterozygous and mosaic patients. This review provides new insight into similarities as well as marked differences regarding the appreciation of mosaicism in these tumor suppressor syndromes.

ERN GENTURIS clinical practice guidelines for the diagnosis, treatment, management and surveillance of people with schwannomatosis

A Guideline Group (GG) was convened from multiple specialties and patients to develop the first comprehensive schwannomatosis guideline. The GG undertook thorough literature review and wrote recommendations for treatment and surveillance. A modified Delphi process was used to gain approval for recommendations which were further altered for maximal consensus. Schwannomatosis is a tumour predisposition syndrome leading to development of multiple benign nerve-sheath non-intra-cutaneous schwannomas that infrequently affect the vestibulocochlear nerves. Two definitive genes (SMARCB1/LZTR1) have been identified on chromosome 22q centromeric to NF2 that cause schwannoma development by a 3-event, 4-hit mechanism leading to complete inactivation of each gene plus NF2. These genes together account for 70-85% of familial schwannomatosis and 30-40% of isolated cases in which there is considerable overlap with mosaic NF2. Craniospinal MRI is generally recommended from symptomatic diagnosis or from age 12-14 if molecularly confirmed in asymptomatic individuals whose relative has schwannomas. Whole-body MRI may also be deployed and can alternate with craniospinal MRI. Ultrasound scans are useful in limbs where typical pain is not associated with palpable lumps. Malignant-Peripheral-Nerve-Sheath-Tumour-MPNST should be suspected in anyone with rapidly growing tumours and/or functional loss especially with SMARCB1-related schwannomatosis. Pain (often intractable to medication) is the most frequent symptom. Surgical removal, the most effective treatment, must be balanced against potential loss of function of adjacent nerves. Assessment of patients' psychosocial needs should be assessed annually as well as review of pain/pain medication. Genetic diagnosis and counselling should be guided ideally by both blood and tumour molecular testing.

Clinical features of multiple spinal schwannomas without vestibular schwannomas

BACKGROUND

Multiple spinal cord tumors in a single patient are very rare and most often seen in cases of neurofibromatosis and associated disorders. Schwannomatosis, which is characterized by the development of multiple schwannomas without vestibular schwannomas, has been newly defined as a distinct form of neurofibromatosis. The purpose of the present study was to describe and review the clinical and radiological features and the management of patients with multiple spinal schwannomas without vestibular schwannomas.

METHODS

Between 1986 and 2016, 19 patients with multiple spinal schwannomas without vestibular schwannoma were diagnosed and treated. Of the 19 patients, 13 were males, and 6 were females. The mean age at the first surgery for spinal schwannoma was 45.2 years old. The mean follow-up period was 123.4 months. The clinical features and radiological findings of the patients with multiple spinal schwannomas were retrospectively reviewed.

RESULTS

Among the 19 patients, there were more than 140 spinal schwannomas. The most common area of spinal schwannoma was the thoracolumbar-lumbar region. Initial symptoms and chief complaints caused by spinal schwannomas were primarily pain in the trunk or extremities in 17 (89.5%) of 19 patients. More than 60 spinal schwannomas were surgically resected. Multiple spinal surgeries were required in six patients. In all 19 patients, surgical treatment has provided successful relief of symptoms and neurological recovery.

CONCLUSIONS

Surgical treatment was safe and effective in patients with multiple spinal schwannomas without vestibular schwannomas. After surgery, we recommend that all patients be followed with magnetic resonance imaging to monitor for asymptomatic tumors or detect new tumors early.

Rare Diseases of the Oral Cavity, Neck, and Pharynx

Diseases occurring with an incidence of less than 1-10 cases per 10 000 individuals are considered as rare. Currently, between 5 000 and 8 000 rare or orphan diseases are known, every year about 250 rare diseases are newly described. Many of those pathologies concern the head and neck area. In many cases, a long time is required to diagnose an orphan disease. The lives of patients who are affected by those diseases are often determined by medical consultations and inpatient stays. Most orphan diseases are of genetic origin and cannot be cured despite medical progress. However, during the last years, the perception of and the knowledge about rare diseases has increased also due to the fact that publicly available databases have been created and self-help groups have been established which foster the autonomy of affected people. Only recently, innovative technical progress in the field of biogenetics allows individually characterizing the genetic origin of rare diseases in single patients. Based on this, it should be possible in the near future to elaborate tailored treatment concepts for patients suffering from rare diseases in the sense of translational and personalized medicine. This article deals with orphan diseases of the lip, oral cavity, pharynx, and cervical soft tissues depicting these developments. The readers will be provided with a compact overview about selected diseases of these anatomical regions. References to further information for medical staff and affected patients support deeper knowledge and lead to the current state of knowledge in this highly dynamic field.

A rare case of schwannomatosis of the extremities

A schwannoma is a benign tumor that arises from the myelin-producing Schwann cells that surround nerves. We herein report a case involving a 55-year-old man who first presented to our clinic with a schwannoma of the posterior tibial nerve and 5 years later with a schwannoma of the ulnar nerve. This is the first report of schwannomatosis of the ulnar and posterior tibial nerves.

Recurrent Schwannomatosis of the Hand

Background: Peripheral nerve sheath tumors (PNSTs) are neoplastic soft tissue masses generated from the abnormal proliferation of Schwann cells. Often, these tumors occur in isolation and are known as schwannomas or neurilemmomas. The presence of multiple schwannomas is known as schwannomatosis. The purpose of this article is 2-fold: (1) to review the relevant literature and describe a unique case of this rare condition; and (2) to emphasize salient clinical considerations in the diagnosis and treatment of schwannomatosis. Methods: In this report, we describe the case of a 52-year-old white man who presented with multiple recurrent soft tissue masses of the right hand. On initial presentation, he described pain across his right hand and index finger, which persisted despite numerous prior operations. The index finger had a flexion contracture around the location of the proximal interphalangeal joint, and there were multiple tender masses along the length of the finger and palm. Results: Segmental excision of the affected radial digital nerve was performed. A pulp flap based on contralateral neurovascular bundle resulted in a sensate, pain-free digit. Tissue pathology confirmed the diagnosis of multiple neurilemmomas. Conclusions: We report the success of a radial digital neurectomy in a patient with widespread neurilemmomas, who had previously excluded that painful digit from use. It was through careful consideration of the preoperative differential diagnosis, by valuing the preoperative imaging, and by considering all surgical options with specific attention paid to skin flap design that this good outcome of a fully sensate, pain-free, mobile index finger was achieved.

Vestibular Schwannoma: What We Know and Where We are Heading

Vestibular schwannoma (VS) is a Schwann cell-derived tumour arising from the vestibulocochlear nerve. Although benign, it represents a threat to intracranial structures due to mass effect and carries a small risk of malignant transformation. VS therefore represents an important healthcare burden. We review the literature regarding pathogenesis, risk factors, and diagnosis of VS. The current and future potential management strategies are also discussed. A narrative review of all relevant papers known to the authors was conducted. The majority of VS remain clinically stable and do not require interventional procedures. Nevertheless, various surgical techniques exist for removing VS, the most common of which are translabyrinthine and retrosigmoid approaches. Due to surgical risks such as hearing loss, facial nerve dysfunction, post-operative headache, and cerebrospinal fluid leakage, a "watch and rescan" approach is adopted for most patients. Radiotherapy is a useful alternative and has been shown to have a similar response for growth restriction. Due to the heterogeneous nature of VS, there is a lack of consensus regarding management of tumours that are too large for conservative management but too small to indicate surgery. Emerging biologic therapies, such as Bevacizumab, Everolimus, and Lapatinib, as well as anti-inflammatories like aspirin are promising potential treatments; however, long-term evidence of their efficacy is required. The knowledge base regarding VS continues to improve. With increased understanding of the pathogenesis of these tumors, we believe future work should focus on pharmacologic intervention. Biologic therapies aimed toward improved patient outcomes are particularly promising.

Segmental schwannomatosis: characteristics in 12 patients

BACKGROUND

Segmental schwannomatosis is characterized by multiple schwannomas affecting one-limb or less than 5 contiguous segments of spine. Its characteristics are not well described in the literature. Our objective was to better describe the demographic and clinical characteristics of this condition.

METHODS

This was a retrospective, bi-center study conducted in two French expert centers for neurofibromatosis and schwannomatosis. The clinical, radiographic, pathological and molecular aspects were extracted from patients' clinical records.

RESULTS

Twelve patients with segmental schwannomatosis were identified. Eight were female and 4 were male. The median age at initial symptom was 29 years (range: 6-60 years) and the median age at diagnosis was 34.5 years (range: 13-65 years). Pain was the initial symptom for the majority of patients (7 of 12). The number of tumors was variable with six patients having more than 10 tumors. Peripheral distribution was seen in all patients. Quality of life could be impaired (median Dermatology Life Quality Index score was 4.5 (range: 2-13). The median duration of follow up was 3 years (range: 1-26). Chronic pain was the main complication (9 of 12 patients). Surgical intervention to control chronic pain was performed for 9 patients of whom 5 experienced recurrence of tumors. Molecular investigations revealed heterozygous LZTR1 variants in 3 of 9 patients.

CONCLUSION

Segmental schwannomatosis is a rare condition that may start early in life and often remains undiagnosed for many years. Pain is the main symptom and consequently could impair the quality of life. Surgery seems to be effective, but recurrences are frequent. Some patients carried heterozygous LZTR1 variants. Further studies are needed to better understand this rare condition.

Schwannomatosis: a genetic and epidemiological study

OBJECTIVES

Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2.

METHODS

Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.8 million) and from across the UK. Point prevalence and birth incidence were calculated from regional birth statistics. Genetic analysis was also performed on NF2, LZTR1 and SMARCB1 on blood and tumour DNA samples when available.

RESULTS

Regional prevalence for schwannomatosis and NF2 were 1 in 126 315 and 50 500, respectively, with calculated birth incidences of 1 in 68 956 and 1 in 27 956. Mosaic NF2 causes a substantial overlap with schwannomatosis resulting in the misdiagnosis of at least 9% of schwannomatosis cases. LZTR1-associated schwannomatosis also causes a small number of cases that are misdiagnosed with NF2 (1%-2%), due to the occurrence of a unilateral vestibular schwannoma. Patients with schwannomatosis had lower numbers of non-vestibular cranial schwannomas, but more peripheral and spinal nerve schwannomas with pain as a predominant presenting symptom. Life expectancy was significantly better in schwannomatosis (mean age at death 76.9) compared with NF2 (mean age at death 66.2; p=0.004).

CONCLUSIONS

Within the highly ascertained North-West England population, schwannomatosis has less than half the birth incidence and prevalence of NF2.

Childhood neurofibromatosis type 2 (NF2) and related disorders: from bench to bedside and biologically targeted therapies

Neurofibromatosis type 2 [NF2; MIM # 101000] is an autosomal dominant disorder characterised by the occurrence of vestibular schwannomas (VSs), schwannomas of other cranial, spinal and cutaneous nerves, cranial and spinal meningiomas and/or other central nervous system (CNS) tumours (e.g., ependymomas, astrocytomas). Additional features include early onset cataracts, optic nerve sheath meningiomas, retinal hamartomas, dermal schwannomas (i.e., NF2-plaques), and (few) café-au-lait spots. Clinically, NF2 children fall into two main groups: (1) congenital NF2 - with bilateral VSs detected as early as the first days to months of life, which can be stable/asymptomatic for one-two decades and suddenly progress; and (2) severe pre-pubertal (Wishart type) NF2- with multiple (and rapidly progressive) CNS tumours other-than-VS, which usually present first, years before VSs [vs. the classical adult (Gardner type) NF2, with bilateral VSs presenting in young adulthood, sometimes as the only disease feature]. Some individuals can develop unilateral VS associated with ipsilateral meningiomas or multiple schwannomas localised to one part of the peripheral nervous system [i.e., mosaic NF2] or multiple non-VS, non-intradermal cranial, spinal and peripheral schwannomas (histologically proven) [schwannomatosis]. NF2 is caused by mutations in the NF2 gene at chromosome 22q12.1, which encodes for a protein called merlin or schwannomin, most similar to the exrin-readixin-moesin (ERM) proteins; mosaicNF2 is due to mosaic phenomena for the NF2 gene, whilst schwannomatosis is caused by coupled germ-line and mosaic mutations either in the SMARCB1 gene [SWNTS1; MIM # 162091] or the LZTR1 gene [SWNTS2; MIM # 615670] both falling within the 22q region and the NF2 gene. Data driven from in vitro and animal studies on the merlin pathway [e.g., post-translational and upstream/downstream regulation] allowed biologically targeted treatment strategies [e.g., Lapatinib, Erlotinib, Bevacizumab] aimed to multiple tumour shrinkage and/or regression and tumour arrest of progression with functional improvement.

Six cases of sporadic schwannomatosis: Topographic distribution and outcomes of peripheral nerve tumors

The diagnosis of schwannomatosis is often overestimated and is based on the existence of multiple peripheral nerve tumors composed exclusively of schwannomas, in the absence of clinical signs of neurofibromatosis type 2 (NF2). Sporadic forms are much more frequent than familial forms. The objective of this study was to describe the distribution of peripheral nerve tumors and investigate the outcomes of schwannomas in the context of sporadic schwannomatosis. We conducted a retrospective study of patients who fulfilled clinical diagnostic criteria for sporadic schwannomatosis. Six patients were reviewed with a mean follow-up of 38.5months (27-60months). Patients' demographic, clinical, radiographic, and pathologic data were extracted. All patients underwent slit-lamp examination, enhanced brain magnetic resonance imaging (MRI) and a spinal MRI. Enucleation that preserved nerve continuity was performed in symptomatic patients. On average, patients were 36years of age at the time of diagnosis with no sex predominance. The topographic distribution of the peripheral nerve tumors was always unilateral and most frequently targeted the upper limb. In four cases, the tumors involved the same peripheral nerve exclusively. The average number of nerve tumors observed per patient was 4.7 (2-8). The outcome after enucleation was marked by the systematic appearance of new tumors. After enucleation, no recurrence or malignant transformation was observed at the final follow-up. There was no transition to a NF2 configuration. The absence of neurofibroma and NF2 criteria makes schwannomatosis a diagnosis of exclusion. While a good prognosis can be expected following enucleation, two risks related to neurofibromatosis type 3 (NF3) are worth monitoring: the transition to NF2, particularly in young patients, and the appearance of new tumors.

Development of human induced pluripotent stem cell (iPSC) line from a 60year old female patient with multiple schwannoma

Peripheral blood was collected from a clinically diagnosed 60-year old female patient with multiple schwannoma. Peripheral blood mononuclear cells (PBMCs) were reprogrammed with the Yamanaka KMOS reprogramming factors using the Sendai-virus reprogramming system. The transgene-free iPSC line showed pluripotency verified by immunofluorescent staining for pluripotency markers, and the iPSC line was able to differentiate into the 3 germ layers in vivo. The iPSC line also showed normal karyotype. This in vitro cellular model will be useful for further pathological studies of multiple schwannoma.

Generation of a human induced pluripotent stem cell (iPSC) line from a 64year old male patient with multiple schwannoma

Peripheral blood was collected from a clinically diagnosed 64-year old male multiple schwannoma patient. Peripheral blood mononuclear cells (PBMCs) were reprogrammed with the Yamanaka KMOS reprogramming factors using the Sendai-virus reprogramming system. The transgene-free iPSC line showed pluripotency verified by immunofluorescent staining for pluripotency markers, and the iPSC line was able to differentiate into the 3 germ layers in vivo. The iPSC line also showed normal karyotype. This in vitro cellular model will be useful for further pathological studies of multiple schwannoma.

Spinal schwannomatosis of the cauda equina in the absence of neurofibromatosis: case report and treatment strategies

Schwannomatosis is a rare tumor syndrome characterized by the presence of multiple benign non-vestibular, non-intradermal schwannomas and by the absence of neurofibromatosis type 1 or 2 syndromes. Multiple schwannomas are clinically and genetically distinct from neurofibromatosis, and the main treatment in case of symptomatic lesions is represented by surgical resection. In case of asymptomatic lesions, the indicated treatment is neuroimaging follow-up (MRI). We are presenting the case of a patient with three schwannomas of the cauda equina, as well as the treatment strategy in the case of this rare pathology.

The molecular pathogenesis of schwannomatosis, a paradigm for the co-involvement of multiple tumour suppressor genes in tumorigenesis

Schwannomatosis is characterized by the predisposition to develop multiple schwannomas and, less commonly, meningiomas. Despite the clinical overlap with neurofibromatosis type 2 (NF2), schwannomatosis is not caused by germline NF2 gene mutations. Instead, germline mutations of either the SMARCB1 or LZTR1 tumour suppressor genes have been identified in 86% of familial and 40% of sporadic schwannomatosis patients. In contrast to patients with rhabdoid tumours, which are due to complete loss-of-function SMARCB1 mutations, individuals with schwannomatosis harbour predominantly hypomorphic SMARCB1 mutations which give rise to the synthesis of mutant proteins with residual function that do not cause rhabdoid tumours. Although biallelic mutations of SMARCB1 or LZTR1 have been detected in the tumours of patients with schwannomatosis, the classical two-hit model of tumorigenesis is insufficient to account for schwannoma growth, since NF2 is also frequently inactivated in these tumours. Consequently, tumorigenesis in schwannomatosis must involve the mutation of at least two different tumour suppressor genes, an occurrence frequently mediated by loss of heterozygosity of large parts of chromosome 22q harbouring not only SMARCB1 and LZTR1 but also NF2. Thus, schwannomatosis is paradigmatic for a tumour predisposition syndrome caused by the concomitant mutational inactivation of two or more tumour suppressor genes. This review provides an overview of current models of tumorigenesis and mutational patterns underlying schwannomatosis that will ultimately help to explain the complex clinical presentation of this rare disease.

Revisiting neurofibromatosis type 2 diagnostic criteria to exclude LZTR1-related schwannomatosis

OBJECTIVE

To determine the specificity of the current clinical diagnostic criteria for neurofibromatosis type 2 (NF2) relative to the requirement for unilateral vestibular schwannoma (VS) and at least 2 other NF2-related tumors.

METHODS

We interrogated our Manchester NF2 database, which contained 205 individuals meeting NF2 criteria who initially presented with a unilateral VS. Of these, 83 (40.7%) went on to develop a contralateral VS. We concentrated our genetic analysis on a group of 70 who initially fulfilled NF2 criteria with a unilateral vestibular schwannoma and at least 2 additional nonintradermal schwannomas.

RESULTS

Overall, 5/70 (7%) individuals with unilateral VS and at least 2 other schwannomas had a pathogenic or likely pathogenic LZTR1 mutation. Twenty of the 70 subsequently developed bilateral disease. Of the remaining 50, 5 (10%) had a germline LZTR1 mutation, equivalent to the number (n = 5) with a germline NF2 mutation.

CONCLUSIONS

The most common etiology for unilateral VS and 2 additional NF2-associated tumors in this cohort was mosaic NF2. Germline LZTR1 and germline NF2 mutations were equally common in our cohort. This indicates that LZTR1 must be considered when making a diagnosis of NF2 in the presence of unilateral VS in individuals without a germline NF2 mutation.

Schwannomatosis of Cervical Vagus Nerve

Cervical vagal schwannoma is a rare entity among lesions presenting as a neck mass. They are usually slow-growing benign lesions closely associated with the vagus nerve. They are usually solitary and asymptomatic. Multiple schwannomas occurring in patients without neurofibromatosis (NF) are rare and have recently been referred to as schwannomatosis. Here, we present a case of a neck mass that had imaging features suggestive of vagal schwannoma and was operated upon. Intraoperatively, it was discovered to be a case of multiple vagal cervical schwannoma, all directly related to the right vagus nerve, and could be resected from the nerve in toto preserving the function of the vagus nerve. Final HPR confirmed our pre-op suspicion of vagal schwannomatosis.

Neurofibromatosis type 2 (NF 2) or schwannomatosis?--Case report study and diagnostic criteria

INTRODUCTION

Neurofibromatosis type 2 (NF2) and schwannomatosis are entities that may, due to the similarity of clinical symptoms, cause diagnostic difficulties. Incidence rate of both diseases is similar and estimated between 1:25,000 and 1:40,000. The genes associated with the development of the aforementioned disorders are located on chromosome 22 and lay in proxmity. Schwannomatosis is characterized by an incomplete penetrance and the risk of its transmission to the offspring is significantly lower than in the case of NF 2. Schwannomatosis clinical characteristic is similar to the NF2, however vestibular schwannomas are not present. Therefore the imaging studies evaluated by an experienced radiologist play a key role in the diagnostic process.

CASE REPORT

Forty two-year-old female hospitalized three times because of the tumors of the spinal canal was admitted to the Department of Neurosurgery and Peripheral Nerve Surgery in 2008 because of the cervical pain syndrome with concomitant headache. She was diagnosed with a schwannomatosis, recently distinguished, the third form of neurofibromatosis. MRI imaging revealed craniocervical junction tumor. Suboccipital craniectomy with concomitant C1-C2 laminectomy was done in order to remove the lesion. After the surgery the patient did not present any deficits in neurological examination and was discharged from hospital in good general condition.

CONCLUSIONS

The patient was diagnosed with schwannomatosis, recently established neurofibromatosis entity which may resemble NF2 clinically. In patients after the age of 30, in whom we observe multiple schwannomas without the concomitant hearing impairment, the diagnosis of schwannomatosis is very likely.

Immortalized Human Schwann Cell Lines Derived From Tumors of Schwannomatosis Patients

Schwannomatosis, a rare form of neurofibromatosis, is characterized predominantly by multiple, often painful, schwannomas throughout the peripheral nervous system. The current standard of care for schwannomatosis is surgical resection. A major obstacle to schwannomatosis research is the lack of robust tumor cell lines. There is a great need for mechanistic and drug discovery studies of schwannomatosis, yet appropriate tools are not currently available. Schwannomatosis tumors are difficult to grow in culture as they survive only a few passages before senescence. Our lab has extensive experience in establishing primary and immortalized human Schwann cell cultures from normal tissue that retain their phenotypes after immortalization. Therefore we took on the challenge of creating immortalized human Schwann cell lines derived from tumors from schwannomatosis patients. We have established and fully characterized 2 schwannomatosis cell lines from 2 separate patients using SV40 virus large T antigen. One patient reported pain and the other did not. The schwannomatosis cell lines were stained with S100B antibodies to confirm Schwann cell identity. The schwannomatosis cells also expressed the Schwann cell markers, p75NTR, S100B, and NGF after multiple passages. Cell morphology was retained following multiple passaging and freeze/ thaw cycles. Gene expression microarray analysis was used to compare the cell lines with their respective parent tumors. No differences in key genes were detected, with the exception that several cell cycle regulators were upregulated in the schwannomatosis cell lines when compared to their parent tumors. This upregulation was apparently a product of cell culturing, as the schwannomatosis cells exhibited the same expression pattern of cell cycle regulatory genes as normal primary human Schwann cells. Cell growth was also similar between normal primary and immortalized tumor cells in culture. Accurate cell lines derived directly from human tumors will serve as invaluable tools for advancing schwannomatosis research, including drug screening.

Diagnosis, Management, and New Therapeutic Options in Childhood Neurofibromatosis Type 2 and Related Forms

Neurofibromatosis type 2 (NF2; MIM # 101000) is an autosomal dominant disorder characterized by the development of vestibular schwannomas (VSs); schwannomas of other cranial, spinal, and cutaneous nerves; cranial and spinal meningiomas or other central nervous system tumors (eg, ependymomas and astrocytomas) or both. Additional features include eye (eg, early onset cataracts, optic nerve sheath meningiomas, retinal or pigment epithelial hamartomas or both, and epithelial retinal membranes) and skin abnormalities (eg, flat dermal [NF2 plaques] or spherical subcutaneous nodular schwannomas or both, and few, atypical café-au-lait spots). Clinically, children with NF2 fall into 2 main groups: (1) congenital NF2 with bilateral VSs detected as early as the first days to months of life, which can be stable or asymptomatic for 1-2 decades and suddenly progress; and (2) severe prepubertal (Wishart type) NF2 with multiple (and rapidly progressive) central nervous system tumors other-than-VS, which usually presents first, years before VSs, both associated with more marked skin and eye involvement (vs the classical mild adult [Gardner type] NF2, with bilateral VSs presenting in young adulthood, sometimes as the only disease feature). Individuals manifesting unilateral VS associated with ipsilateral meningiomas or multiple schwannomas localized to a part of the peripheral nervous system have mosaic or segmental NF2; individuals developing multiple nonVS, nonintradermal cranial, spinal, and peripheral schwannomas (histologically proven) have schwannomatosis (SWNTS). NF2 is caused by mutations in the NF2 gene at chromosome 22q12.1, which encodes for a protein called merlin or schwannomin, most similar to the exrin-readixin-moesin proteins; mosaic or segmental NF2 is because of mosaic phenomena for the NF2 gene, whereas SWNTS is caused by germline and possibly mosaic mutations either in the SMARCB1 gene (SWNTS1; MIM # 162091) or the LZTR1 gene (SWNTS2; MIM # 615670), both falling within the 22q region. Data driven from in vitro and animal studies on the merlin pathway allowed biologically targeted treatment strategies (employing Lapatinib, Erlotinib, Everolimus, Picropodophyllin, OSU.03012, Imatinib, Sorafenib, and Bevacizumab) aimed at multiple tumor shrinkage or regression or both and tumor arrest of progression with functional improvement.

Clinical features of spinal schwannomas in 65 patients with schwannomatosis compared with 831 with solitary schwannomas and 102 with neurofibromatosis Type 2: a retrospective study at a single institution

OBJECTIVE

The aim of this study was to evaluate the clinical features of spinal schwannomas in patients with schwannomatosis and compare them with a large cohort of patients with solitary schwannomas and neurofibromatosis Type 2 (NF2).

METHODS

The study was a retrospective review of 831 patients with solitary schwannomas, 65 with schwannomatosis, and 102 with NF2. The clinical, radiographic, and pathological data were extracted with specific attention to the age at onset, location of tumors, initial symptoms, family history, and treatment outcome.

RESULTS

The male-to-female ratio of patients with schwannomatosis (72.3% vs 27.7%) was significantly higher than that of patients with solitary schwannomas (53.3% vs 46.7%) and NF2 (54.0% vs 46.0%), respectively (chi-square test, p = 0.012). The mean age at the first spinal schwannoma operation of patients with NF2 (24.7 ± 10.2 years) was significantly younger than that of patients with solitary schwannomas (44.8 ± 13.2 years) and schwannomatosis (44.4 ± 14.1 years; 1-way ANOVA, p < 0.001). The initial symptoms were similar among the 3 groups, with pain being the most common. The distribution of spinal tumors among the 3 groups was significantly different. The peak locations of spinal schwannomas in patients with solitary schwannomas were at C1-3 and T12-L3; in schwannomatosis, the peak location was at T12-L5. A preferred spinal location was not evident for intradural-extramedullary tumors in NF2. Only a slight prominence in the lumbar area could be observed. The patients in the 3 groups obtained similar benefits from the operation; the recovery rates in the patients with solitary schwannomas, NF2, and schwannomatosis were 50.1%, 38.0%, and 53.9%, respectively. The prognosis varied among spinal schwannomas in the patients with schwannomatosis. Up until the last date of follow-up, most patients with schwannomatosis (81.5%) had undergone a single spinal operation, but 12 patients (18.5%) had undergone multiple spinal operations. Patients with nonsegmental schwannomatosis or those with early onset disease seemed to have a poor prognosis; they were more likely to undergo multiple spinal operations. Small cauda equina nodules were common in patients with schwannomatosis (46.7%) and NF2 (86.9%); these small schwannomas appeared to have relatively static behavior. Two patients suspicious for schwannomatosis were diagnosed with NF2 with the detection of constitutional NF2 mutations; 1 had unilateral vestibular schwannoma, and the other had suspicious bilateral trigeminal schwannomas.

CONCLUSIONS

The clinical features of spinal schwannomas vary among patients with solitary schwannomas, NF2, and schwannomatosis. Spinal schwannomas of patients with NF2 appear to be more aggressive than those in patients with solitary schwannomas and schwannomatosis. Spinal schwannomas of schwannomatosis predominate in the lumbar area, and most of them can be treated successfully with surgery. The prognosis varies among spinal schwannomas of schwannomatosis; some patients may need multiple operations due to newly developed schwannomas. Sometimes, it is difficult to differentiate schwannomatosis from NF2 based on clinical manifestations. It is prudent to perform close follow-up examinations in patients with undetermined schwannomatosis and their offspring.

Schwannomatosis on a single foot: a case report

Schwannomatosis has been recently recognized as the third major type of neurofibromatosis. It causes multiple schwannomas without the vestibular tumors that are diagnostic of neurofibromatosis type 2. Schwannoma is rarely found in the foot, and it is still rarer to find multiple schawannomas in a single peripheral nerve on the foot. In this article, we describe a case of schwannomatosis case on a single foot.

LEVELS OF EVIDENCE

Case report, Level IV.

Quality of life among children and adolescents with neurofibromatosis 1: a systematic review of the literature

The aim of this research is to identify, within a systematic review, aspects of quality of life (QoL) that are adversely affected in children and adolescents with neurofibromatosis (NF), and to report predictors of quality of life in this population. Published reports of original research were included if they described QoL in children and/or adolescents with NF, and met methodological quality according to a list of predefined criteria. Seven studies conducted between 2006 and 2013 met inclusion criteria. All seven studies examined patients with NF1 and reported that these patients have lower general QoL compared to population norms. Parents' proxy ratings of QoL were generally lower than children's self-report ratings. By parent proxy, familial NF1 was a strong protective factor for QoL, while the opposite was found by child report. By parent proxy, male sex was significantly associated with lower scores on the parental time impact of QoL. Skin-related QoL was only slightly altered in this population, vision-specific QoL was impacted only in patients with vision loss. The majority of findings regarding predictors of QoL in children with NF1 were weak, due to a lack of studies, heterogeneity of samples, and heterogeneity of measurements/predictors assessed. Future studies should examine more comprehensively the psychosocial factors affecting the NF population, especially in young patients with NF2 and schwannomatosis, who have been neglected in prior research. The use of consistent QoL measures is preferred to allow better comparison among studies and conditions. Interventions, including comprehensive mind-body treatments, are warranted to address impaired QoL in children and adolescents with NF1.

Quality of life among children and adolescents with neurofibromatosis 1: a systematic review of the literature

The aim of this research is to identify, within a systematic review, aspects of quality of life (QoL) that are adversely affected in children and adolescents with neurofibromatosis (NF), and to report predictors of quality of life in this population. Published reports of original research were included if they described QoL in children and/or adolescents with NF, and met methodological quality according to a list of predefined criteria. Seven studies conducted between 2006 and 2013 met inclusion criteria. All seven studies examined patients with NF1 and reported that these patients have lower general QoL compared to population norms. Parents' proxy ratings of QoL were generally lower than children's self-report ratings. By parent proxy, familial NF1 was a strong protective factor for QoL, while the opposite was found by child report. By parent proxy, male sex was significantly associated with lower scores on the parental time impact of QoL. Skin-related QoL was only slightly altered in this population, vision-specific QoL was impacted only in patients with vision loss. The majority of findings regarding predictors of QoL in children with NF1 were weak, due to a lack of studies, heterogeneity of samples, and heterogeneity of measurements/predictors assessed. Future studies should examine more comprehensively the psychosocial factors affecting the NF population, especially in young patients with NF2 and schwannomatosis, who have been neglected in prior research. The use of consistent QoL measures is preferred to allow better comparison among studies and conditions. Interventions, including comprehensive mind-body treatments, are warranted to address impaired QoL in children and adolescents with NF1.

Segmental neurofibromatosis type 2: discriminating two hit from four hit in a patient presenting multiple schwannomas confined to one limb

Background

A clinical overlap exists between mosaic Neurofibromatosis Type 2 and sporadic Schwannomatosis conditions. In these cases a molecular analysis of tumors is recommended for a proper genetic diagnostics. This analysis is challenged by the fact that schwannomas in both conditions bear a somatic double inactivation of the NF2 gene. However, SMARCB1-associated schwannomas follow a four-hit, three-step model, in which both alleles of SMARCB1 and NF2 genes are inactivated in the tumor, with one of the steps being always the loss of a big part of chromosome 22 involving both loci.

Case presentation

Here we report a 36-year-old woman who only presented multiple subcutaneous schwannomas on her right leg. To help discriminate between both possible diagnoses, an exhaustive molecular genetic and genomic analysis was performed on two schwannomas of the patient, consisting in cDNA and DNA sequencing, MLPA, microsatellite multiplex PCR and SNP-array analyses. The loss of a big part of chromosome 22 (22q12.1q13.33) was identified in both tumors. However, this loss involved the NF2 but not the SMARCB1 locus. SNP-array analysis revealed the presence of the same deletion breakpoint in both schwannomas, indicating that this alteration was actually the first NF2 inactivating hit. In addition, a distinct NF2 point mutation in each tumor was identified, representing independent second hits. In accordance with these results, no deletions or point mutations in the SMARCB1 gene were identified. None of the mutations were present in the blood. Two of the patient’s children inherited chromosome 22 deleted in schwannomas of the mother, but in its wild type form.

Conclusions

These results conclusively confirm the segmental mosaic NF2 nature of the clinical phenotype presented.

Neurofibromatosis type 2

Type 2 neurofibromatosis (NF2) is an autosomal dominant disorder caused by mutations in the NF2 tumor suppressor gene NF2 on chromosome 22. Around 1 in 33000 people are born with an NF2 mutation although more than one-third of the 60% of de novo cases are not conceived with the mutation but this develops later in embryogenesis (mosaics). NF2 has a substantial effect on life expectancy and individuals with a constitutional truncating mutation have the worst prognosis. The vast majority of people with NF2 will develop bilateral vestibular schwannomas with many developing schwannomas on other cranial, spinal and peripheral nerves. Cranial and spinal meningiomas and intraspinal low grade indolent ependymomas are the other major tumor features. Cutaneous features can be subtle with only 70% having evidence of intracutaneous plaque-like schwannomas or subcutaneous lesions on peripheral nerves. Café-au-lait patches are more frequent than in the general population but in only around 1% will meet NIH criteria for NF1.

Rhabdoid tumor predisposition syndrome

Rhabdoid tumors (RT), or malignant rhabdoid tumors, are among the most aggressive and lethal forms of human cancer. They can arise in any location in the body but are most commonly observed in the brain, where they are called atypical teratoid/rhabdoid tumors (AT/RT), and in the kidneys, where they are called rhabdoid tumors of the kidney. The vast majority of rhabdoid tumors present with a loss of function in the SMARCB1 gene, also known as INI1, BAF47, and hSNF5, a core member of the SWI/SNF chromatin-remodeling complex. Recently, mutations in a 2nd locus of the SWI/SNF complex, the SMARCA4 gene, also known as BRG1, were found in rhabdoid tumors with retention of SMARCB1 expression. Familial cases may occur in a condition known as rhabdoid tumor predisposition syndrome (RTPS). In RTPS, germline inactivation of 1 allele of a gene occurs. When the mutation occurs in the SMARCB1 gene, the syndrome is called RTPS1, and when the mutation occurs in the SMARCA4 gene it is called RTPS2. Children presenting with RTPS tend to develop tumors at a younger age, but the impact that germline mutation has on survival remains unclear. Adults who carry the mutation tend to develop multiple schwannomas. The diagnosis of RTPS should be considered in patients with RT, especially if they have multiple primary tumors, and/or in individuals with a family history of RT. Because germline mutations result in an increased risk of carriers developing RT, genetic counseling for families with this condition is recommended.

[Nerve sheath tumours]

Peripheral nerve sheath tumors are common neoplasms in daily practice. Diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer; but on occasion, they are diagnostically challenging (especially with locally aggressive and malignant tumors). This article aims to provide an update of the data (clinical, histological, immunohistochemistry and genomic) of benign, intermediate and malignant peripheral nerve sheath tumors, thanks to the latest WHO "Classification of Tumors of Soft Tissue and Bone", published in 2013, which includes a new chapter on "Nerve Sheath Tumors". Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches.

Expanding the mutational spectrum of LZTR1 in schwannomatosis

Schwannomatosis is characterized by the development of multiple non-vestibular, non-intradermal schwannomas. Constitutional inactivating variants in two genes, SMARCB1 and, very recently, LZTR1, have been reported. We performed exome sequencing of 13 schwannomatosis patients from 11 families without SMARCB1 deleterious variants. We identified four individuals with heterozygous loss-of-function variants in LZTR1. Sequencing of the germline of 60 additional patients identified 18 additional heterozygous variants in LZTR1. We identified LZTR1 variants in 43% and 30% of familial (three of the seven families) and sporadic patients, respectively. In addition, we tested LZTR1 protein immunostaining in 22 tumors from nine unrelated patients with and without LZTR1 deleterious variants. Tumors from individuals with LZTR1 variants lost the protein expression in at least a subset of tumor cells, consistent with a tumor suppressor mechanism. In conclusion, our study demonstrates that molecular analysis of LZTR1 may contribute to the molecular characterization of schwannomatosis patients, in addition to NF2 mutational analysis and the detection of chromosome 22 losses in tumor tissue. It will be especially useful in differentiating schwannomatosis from mosaic Neurofibromatosis type 2 (NF2). However, the role of LZTR1 in the pathogenesis of schwannomatosis needs further elucidation.

Germline loss-of-function mutations in LZTR1 predispose to an inherited disorder of multiple schwannomas

Constitutional SMARCB1 mutations at 22q11.23 have been found in ∼50% of familial and <10% of sporadic schwannomatosis cases. We sequenced highly conserved regions along 22q from eight individuals with schwannomatosis whose schwannomas involved somatic loss of one copy of 22q, encompassing SMARCB1 and NF2, with a different somatic mutation of the other NF2 allele in every schwannoma but no mutation of the remaining SMARCB1 allele in blood and tumor samples. LZTR1 germline mutations were identified in seven of the eight cases. LZTR1 sequencing in 12 further cases with the same molecular signature identified 9 additional germline mutations. Loss of heterozygosity with retention of an LZTR1 mutation was present in all 25 schwannomas studied. Mutations segregated with disease in all available affected first-degree relatives, although four asymptomatic parents also carried an LZTR1 mutation. Our findings identify LZTR1 as a gene predisposing to an autosomal dominant inherited disorder of multiple schwannomas in ∼80% of 22q-related schwannomatosis cases lacking mutation in SMARCB1.

Schwannomatosis presenting as pancreatic and submandibular gland schwannoma

Schwannomatosis is a well-established third form of neurofibromatosis, characterized by the presence of multiple non-vestibular, non-intradermal schwannomas, often associated with chronic pain. Herein, we report a 41-year-old man with a history of paternal neurofibromatosis 1, who presented with partially cystic tumors in the pancreas and in the right submandibular gland. Besides, he complained of neuropathic pain in the right inguinal and suprapubic area. Magnetic resonance imaging revealed multiple intradural-extramedullary tumors at the cervical, thoracic and lumbar spinal canal, suggestive of schwannomas. The vestibular nerves were not involved. Pathological examination of the glandular tumors disclosed benign schwannomas. These tumors had substantial myxoid stroma and prominent cystic change, and showed a mosaic pattern of loss of INI1/SMARCB1 expression by immunohistochemistry. Later, the patient developed three nodules in the right lung which were interpreted as schwannomas. To our knowledge, this is the first report of schwannomatosis presenting as pancreatic and salivary gland schwannomas.

A rare occurrence and management of familial schwannomatosis

We are presenting a familial schwannomatosis without the features of neurofibromatosis (NF). We retrospectively reviewed the hospital charts, radiology films, operative notes and pathology slides of the patient. There was a family history of schwannomatosis. The patient had contrast-enhanced MRI, which was negative for vestibular schwannomas. The patient underwent surgical excision of symptomatic lesions. Histopathology confirmed these lesions as schwannomas consisting of areas of Antoni A and B, and immunohistochemical study was positive for S-100 protein. We recommend surgery for symptomatic lesions. Asymptomatic tumours can be monitored. Regular follow-up is essential as they may develop fresh lesions at any time. The relevant literature is discussed.

Update from the 2011 International Schwannomatosis Workshop: From genetics to diagnostic criteria

Schwannomatosis is the third major form of neurofibromatosis and is characterized by the development of multiple schwannomas in the absence of bilateral vestibular schwannomas. The 2011 Schwannomatosis Update was organized by the Children's Tumor Foundation (www.ctf.org) and held in Los Angeles, CA, from June 5-8, 2011. This article summarizes the highlights presented at the Conference and represents the "state-of-the-field" in 2011. Genetic studies indicate that constitutional mutations in the SMARCB1 tumor suppressor gene occur in 40-50% of familial cases and in 8-10% of sporadic cases of schwannomatosis. Tumorigenesis is thought to occur through a four-hit, three-step model, beginning with a germline mutation in SMARCB1 (hit 1), followed by loss of a portion of chromosome 22 that contains the second SMARCB1 allele and one NF2 allele (hits 2 and 3), followed by mutation of the remaining wild-type NF2 allele (hit 4). Insights from research on HIV and pediatric rhabdoid tumors have shed light on potential molecular pathways that are dysregulated in schwannomatosis-related schwannomas. Mouse models of schwannomatosis have been developed and promise to further expand our understanding of tumorigenesis and the tumor microenvironment. Clinical reports have described the occurrence of intracranial meningiomas in schwannomatosis patients and in families with germline SMARCB1 mutations. The authors propose updated diagnostic criteria to incorporate new clinical and genetic findings since 2005. In the next 5 years, the authors expect that advances in basic research in the pathogenesis of schwannomatosis will lead toward clinical investigations of potential drug therapies.

Regression of schwannomas induced by adeno-associated virus-mediated delivery of caspase-1

Schwannomas are tumors formed by proliferation of dedifferentiated Schwann cells. Patients with neurofibromatosis 2 (NF2) and schwannomatosis develop multiple schwannomas in peripheral and cranial nerves. Although benign, these tumors can cause extreme pain and compromise sensory/motor functions, including hearing and vision. At present, surgical resection is the main treatment modality, but it can be problematic because of tumor inaccessibility and risk of nerve damage. We have explored gene therapy for schwannomas, using a model in which immortalized human NF2 schwannoma cells expressing a fluorescent protein and luciferase are implanted in the sciatic nerve of nude mice. Direct injection of an adeno-associated virus (AAV) serotype 1 vector encoding caspase-1 (ICE) under the Schwann-cell specific promoter, P0, leads to regression of these tumors with essentially no vector-mediated neuropathology, and no changes in sensory or motor function. In a related NF2 xenograft model designed to cause measurable pain behavior, the same gene therapy leads to tumor regression and concordant resolution of tumor-associated pain. This AAV1-P0-ICE vector holds promise for clinical treatment of schwannomas by direct intratumoral injection to achieve reduction in tumor size and normalization of neuronal function.

Recurrent orbital schwannomas: clinical course and histopathologic correlation

Background

Schwannomas are slow-growing typically encapsulated tumors composed of differentiated Schwann cells, the primary class of peripheral glial cells. Complete excision is the treatment of choice for orbital schwannomas that cause pain, disfigurement, diplopia, or optic neuropathy. The presence of multiple schwannomas in a single patient suggests possible association with neurofibromatosis type 2 (NF2) or schwannomatosis.

Case presentation

We present 2 patients who experienced recurrent orbital schwannoma without evidence for neurofibromatosis. The recurrence in one patient, a 59-year old man, occurred 6 years after complete excision of the initial tumor. This recurrence consisted of 2 independent tumors in the same orbit. The recurrence in the second patient, a 5 year-old girl, occurred multiple times within days to weeks of partial excisions until eventually a complete excision was performed.

Conclusion

The clinical history, histopathologic features and particularly the intraoperative findings suggest that the 59 year old man suffers from orbital schwannomatosis, while the rapid recurrence in the second patient correlated with the cellular features of her plexiform schwannoma. Hence, the recurrence in each patient is linked to a different etiology, with implications for treatment and patient counseling given the difficulty in treating orbital schwannomatosis. To our knowledge, this is the first description of isolated orbital schwannomatosis.

Clinical features of schwannomatosis: a retrospective analysis of 87 patients

BACKGROUND

Schwannomatosis is a recently recognized form of neurofibromatosis characterized by multiple noncutaneous schwannomas, a histologically benign nerve sheath tumor. As more cases are identified, the reported phenotype continues to expand and evolve. We describe the spectrum of clinical findings in a cohort of patients meeting established criteria for schwannomatosis.

METHODS

We retrospectively reviewed the clinical records of patients seen at our institution from 1995-2011 who fulfilled either research or clinical criteria for schwannomatosis. Clinical, radiographic, and pathologic data were extracted with attention to age at onset, location of tumors, ophthalmologic evaluation, family history, and other stigmata of neurofibromatosis 1 (NF1) or NF2.

RESULTS

Eighty-seven patients met the criteria for the study. The most common presentation was pain unassociated with a mass (46%). Seventy-seven of 87 (89%) patients had peripheral schwannomas, 49 of 66 (74%) had spinal schwannomas, seven of 77 (9%) had nonvestibular intracranial schwannomas, and four of 77 (5%) had intracranial meningiomas. Three patients were initially diagnosed with a malignant peripheral nerve sheath tumor; however, following pathologic review, the diagnoses were revised in all three cases. Chronic pain was the most common symptom (68%) and usually persisted despite aggressive surgical and medical management. Other common diagnoses included headaches, depression, and anxiety.

CONCLUSIONS

Peripheral and spinal schwannomas are common in schwannomatosis patients. Severe pain is difficult to treat in these patients and often associated with anxiety and depression. These findings support a proactive surveillance plan to identify tumors by magnetic resonance imaging scan in order to optimize surgical treatment and to treat associated pain, anxiety, and depression.

Tumors of central and peripheral nervous system associated with inherited genetic syndromes

There are several genetic syndromes that predispose to the development of tumors of the nervous system. In the present study, we provide a review of the tumors that are associated with neurofibromatosis type 1, neurofibromatosis type 2, tuberous sclerosis complex, von Hippel-Lindau disease, Li-Fraumeni syndrome, Cowden disease, Turcot syndrome, nevoid basal cell carcinoma syndrome (Gorlin syndrome) and rhabdoid predisposition syndrome, which are the most common.

Spinal ependymomas in neurofibromatosis Type 2: a retrospective analysis of 55 patients

OBJECT

The aim of this paper was to define the clinical characteristics of spinal ependymomas associated with neurofibromatosis Type 2 (NF2).

METHODS

The authors retrospectively reviewed the clinical records of patients with NF2 who had imaging findings consistent with ependymomas and were seen at Massachusetts General Hospital between 1994 and 2007. Clinical characteristics of these patients were obtained from hospital records, imaging studies, surgical reports, and pathology reports. Mutational analysis of the NF2 gene was performed in 37 of 44 unrelated patients.

RESULTS

Fifty-five patients met inclusion criteria for the study. The median age at diagnosis of NF2 was 21 years; the median time after diagnosis until identification of ependymomas was 5 years. Multiple ependymomas were present in 58% of patients. The most common site of involvement was the cervical cord or cervicomedullary junction (86% of imaging studies), followed by the thoracic and lumbar cords (62% and 8%, respectively). The majority of patients had no symptoms related to their tumors (42 patients [76%]). After a median follow-up of 50 months, surgery was performed in 11 patients (20%) for symptomatic progression (indications for surgery). Mutational analysis of the NF2 gene detected alterations in 28 (76%) of 37 unrelated patients, with nonsense and frameshift mutations accounting for 64% of detected mutations. The high rate of truncating mutations may help explain the high tumor burden in these patients.

CONCLUSIONS

Neurofibromatosis Type 2-related ependymomas exhibit an indolent growth pattern with tumor progression limited to a minority of patients. The authors believe that surveillance is reasonable for asymptomatic ependymomas, including those with cystic areas that expand the cord. For symptomatic tumors, resection may be warranted depending on age, overall clinical status, and ease of resectability.

Spinal schwannomatosis in the absence of neurofibromatosis: A very rare condition

Schwannomatosis is defined as an extremely rare tumors syndrome characterized by the presence of multiple schwannomas in the absence of typical signs of NF1 and NF2 syndromes. The genetic and molecular analysis performed on these tumors makes it possible to name schwannomatosis as distinct clinical and genetic syndrome. The treatment in the case of symptomatic lesions is surgical removal; if the lesions are asymptomatic it is better to perform serial MRI studies. Given the high incidence of developing additional lesions in patients with schwannomatosis, it remains imperative to perform serial brain and spinal cord MRI studies during follow-up. The differential diagnosis is important including clinical and radiological criteria plus molecular genetic analysis of tumor cells and lymphocyte DNA. We report a rare case of spinal schwannomatosis in which genetic analysis performed on surgical samples showed two different mutations in the cells of the two lesions.

Schwannomatosis, sporadic schwannomatosis, and familial schwannomatosis: a surgical series with long-term follow-up. Clinical article

OBJECT

The aim of this study was to provide disease-specific information about schwannomatosis in its different forms and to present 2 particular cases of malignant schwannomas in the context of familial schwannomatosis (FS).

METHODS

The authors analyzed patients with pathologically defined schwannomas and identified those with varied forms of schwannomatosis. Each case was retrospectively analyzed for patient sex and age, number of operations and tumors excised, symptoms, location and size of tumors, extent of resection, nerve function pre- and postoperatively, complications, other nonsurgically treated tumors, malignancy, results of brain MR imaging, and follow-up data.

RESULTS

One hundred fifty-eight patients underwent the excision of 216 schwannomas. One hundred forty-two patients presented with solitary schwannomas, 2 had neurofibromatosis Type 2 (NF2), and 14 presented with schwannomatosis. The average follow-up was 52 months. Six individuals had sporadic schwannomatosis, whereas 8 had the familial form of the disease. These 14 patients had an average age of 28.3 years at the time of disease onset (median 27.5 years) and 35.4 years at the time of the first operation (median 37 years) Thirteen of the 14 patients with schwannomatosis experienced pain as the first symptom. Eight (57%) of the 14 patients presented with at least 1 tumor in the spinal canal or attached to the spinal nerve roots. Malignant schwannomas developed in 2 patients from the same family during the follow-up.

CONCLUSIONS

Patients suffering from schwannomatosis tend to be younger than those presenting with solitary schwannomas. Therefore, individuals presenting at a young age with multiple schwannomas but not meeting the criteria for NF2 should prompt the physician to suspect schwannomatosis. Patients with schwannomatosis who report pain should be exhaustively examined. The spine is affected in the majority of patients, and MR imaging of the spine should be part of the routine evaluation. Rapid enlargement of schwannomas in the context of FS should raise suspicion of malignant transformation.

A rare case of multiple schwannomas presenting with scrotal mass: a probable case of schwannomatosis

We report a rare case of multiple schwannomas presenting with scrotal mass. In the present case, a scrotal schwannoma developed in a 66-year-old man with a history of brain tumor surgery. Investigating the patient's past history lead to the diagnosis as probable schwannomatosis. Patients with schwannomatosis are at increased risk of developing multiple schwannomas and these patients need regular surveillance. In this regard, the present case highlights the importance of thorough history taking in patients with scrotal schwannoma.

Molecular biology of familial and sporadic vestibular schwannomas: implications for novel therapeutics

Vestibular schwannomas (VSs) are benign tumors arising from the sheath of cranial nerve VIII. The pathogenesis underlying most familial and sporadic VSs has been linked to a mutation in a single gene, the neurofibromin 2 (NF2) gene located on chromosome 22, band q11-13.1. In this review, the authors summarized what is known about the epidemiology of NF2 mutations and patients with VSs. The authors also discuss the function of the NF2 gene product, merlin, and describe the known and hypothetical effects of genetic mutations that lead to merlin dysfunction on a broad variety of cellular and histological end points. A better understanding of the molecular pathobiology of VSs may lead to novel therapeutics to augment current modalities of treatment while minimizing morbidity.

SMARCB1/INI1 maternal germ line mosaicism in schwannomatosis

Schwannomatosis is characterized by the development of multiple schwannomas of the nervous system, but without the occurrence of vestibular schwannomas. Most cases of schwannomatosis are thought to be sporadic, representing the first case in a family due to a new mutation in the causative gene. We recently identified SMARCB1/INI1 as a schwannomatosis-predisposing gene. Here, we analyzed this gene in a schwannomatosis family with two affected children, but with clinically unaffected parents. Both affected individuals carried a constitutional SMARCB1 mutation, c.1118+ 1G>A, that changes the donor splice site sequence of intron 8, causing skipping of exon 8 and resulting in the in-frame deletion of 132 nucleotides in the transcript. The mutation was not evident in constitutional DNA of the parents. Haplotyping revealed that the chromosome 22 segment that carries the mutant SMARCB1 allele originated from the mother. She transferred the same chromosome 22 segment, however, with a wild-type SMARCB1 copy, to a third unaffected child. Our findings indicate that the mother is germ line mosaic for the SMARCB1 mutation. In conclusion, our study shows for the first time that germ line mosaicism may occur in schwannomatosis, which has implications for genetic counseling in this disease.