Updated diagnostic criteria and nomenclature for neurofibromatosis type 2 and schwannomatosis: An international consensus recommendation.

PURPOSE: Neurofibromatosis type 2 (NF2) and schwannomatosis (SWN) are genetically distinct tumor predisposition syndromes with overlapping phenotypes. We sought to update the diagnostic criteria for NF2 and SWN by incorporating recent advances in genetics, ophthalmology, neuropathology, and neuroimaging. METHODS: We used a multistep process, beginning with a Delphi method involving global disease experts and subsequently involving non-neurofibromatosis clinical experts, patients, and foundations/patient advocacy groups. RESULTS: We reached consensus on the minimal clinical and genetic criteria for diagnosing NF2 and SWN. These criteria incorporate mosaic forms of these conditions. In addition, we recommend updated nomenclature for these disorders to emphasize their phenotypic overlap and to minimize misdiagnosis with neurofibromatosis type 1. CONCLUSION: The updated criteria for NF2 and SWN incorporate clinical features and genetic testing, with a focus on using molecular data to differentiate the 2 conditions. It is likely that continued refinement of these new criteria will be necessary as investigators study the diagnostic properties of the revised criteria and identify new genes associated with SWN. In the revised nomenclature, the term "neurofibromatosis 2" has been retired to improve diagnostic specificity.

Revised diagnostic criteria for neurofibromatosis type 1 and Legius syndrome: an international consensus recommendation.

PURPOSE: By incorporating major developments in genetics, ophthalmology, dermatology, and neuroimaging, to revise the diagnostic criteria for neurofibromatosis type 1 (NF1) and to establish diagnostic criteria for Legius syndrome (LGSS). METHODS: We used a multistep process, beginning with a Delphi method involving global experts and subsequently involving non-NF experts, patients, and foundations/patient advocacy groups. RESULTS: We reached consensus on the minimal clinical and genetic criteria for diagnosing and differentiating NF1 and LGSS, which have phenotypic overlap in young patients with pigmentary findings. Criteria for the mosaic forms of these conditions are also recommended. CONCLUSION: The revised criteria for NF1 incorporate new clinical features and genetic testing, whereas the criteria for LGSS were created to differentiate the two conditions. It is likely that continued refinement of these new criteria will be necessary as investigators (1) study the diagnostic properties of the revised criteria, (2) reconsider criteria not included in this process, and (3) identify new clinical and other features of these conditions. For this reason, we propose an initiative to update periodically the diagnostic criteria for NF1 and LGSS.

Psychiatric disorders in individuals with neurofibromatosis 1 in Denmark: A nationwide register-based cohort study.

The aim of this study was to assess the risks of psychiatric disorders in a large cohort of 905 individuals with NF1 and 7614 population comparisons matched on sex and year of birth. The cohort was linked to the Danish Psychiatric Central Research Register to ascertain information on hospital contacts for psychiatric disorders based on the International Classification of Diseases version 8 and 10. The hazard ratio (HR) for a first psychiatric hospital contact was higher in girls (4.19, 95% confidence interval [CI] 1.81-9.69) and boys with NF1 (5.02, 95% CI 3.27-7.69) <7 years of age than in the population comparisons. Both sexes had increased HRs for developmental disorders, including attention deficit/hyperactivity disorders, autism spectrum disorders, and intellectual disabilities in childhood. Females with NF1 had also increased HRs for unipolar depression, other emotional and behavioral disorders, and severe stress reaction and adjustment disorders in early adulthood. The HRs for psychoses, schizophrenia, bipolar disorders, and substance abuse were similar in individuals with NF1 and the population comparisons. Finally, the cumulative incidence of a first hospital contact due to any psychiatric disorder by age 30 years was 35% (95% CI 29-41) in females and 28% (95% CI 19-37) in males with NF1. Thus, screening for psychiatric disorders may be important for early diagnosis and facilitation of appropriate and effective treatment in individuals with NF1.

Multisystem burden of neurofibromatosis 1 in Denmark: registry- and population-based rates of hospitalizations over the life span.

PURPOSE: The aim was to assess lifetime risk for hospitalization in individuals with neurofibromatosis 1 (NF1). METHODS: The 2467 individuals discharged with a diagnosis indicating NF1 or followed in a clinical center for NF1 were matched to 20,132 general population comparisons. Based on diagnoses in 12 main diagnostic groups and 146 subcategories, we calculated rate ratios (RRs), absolute excess risks (AERs), and hazard ratios for hospitalizations. RESULTS: The RR for any first hospitalization among individuals with NF1 was 2.3 (95% confidence interval 2.2-2.5). A high AER was seen for all 12 main diagnostic groups, dominated by disorders of the nervous system (14.5% of all AERs), benign (13.6%) and malignant neoplasms (13.4%), and disorders of the digestive (10.5%) and respiratory systems (10.3%). Neoplasms, nerve and peripheral ganglia disease, pneumonia, epilepsy, bone and joint disorders, and intestinal infections were major contributors to the excess disease burden caused by NF1. Individuals with NF1 had more hospitalizations and spent more days in hospital than the comparisons. The increased risk for any hospitalization was observed for both children and adults, with or without an associated cancer. CONCLUSION: NF1 causes an overall greater likelihood of hospitalization, with frequent and longer hospitalizations involving all organ systems throughout life.

Prevalence and clinicopathological characteristics of lipomatous neurofibromas in neurofibromatosis 1: An investigation of 229 cutaneous neurofibromas and a systematic review of the literature.

BACKGROUND: Lipomatous neurofibroma (Lnf) is a histopathological variant with adipocytes noted among cells of cutaneous neurofibromas. We aimed to investigate the prevalence and clinicopathological features of Lnfs of neurofibromatosis 1 (NF1)-associated cutaneous neurofibromas and to review the literature systematically. We also evaluated the expression of leptin (a hormone involved in lipid metabolism) in neurofibromas to better understand the pathogenesis of Lnfs. METHODS: A prospective histologic study was conducted on 229 cutaneous neurofibromas from 85 NF1 individuals. Leptin expression was immunohistochemically evaluated in 111 cutaneous neurofibromas. To systematically review the literature, two authors independently performed literature searches without year restriction. RESULTS: Forty (17.5%) neurofibromas were lipomatous. Lnfs were significantly larger lesions and associated with females. Eighteen (7.9%) of all neurofibromas had multinucleated floret-like giant cells, and these were associated with Lnfs. All neurofibromas expressed leptin. We systematically reviewed 13 articles. Three large studies investigated Lnfs mainly in sporadic neurofibromas and suggested that 0.3% to 8.0% of tumors (NF1 and sporadic) are Lnfs. CONCLUSION: In NF1, Lnfs are common, mainly in larger tumors and women. All cutaneous NF1-neurofibromas express leptin. It is unknown if the expression of leptin accounts for the lipomatous variant, but it may have a role in the pathogenesis of cutaneous neurofibroma.

The path forward: 2015 International Children's Tumor Foundation conference on neurofibromatosis type 1, type 2, and schwannomatosis.

The Annual Children's Tumor Foundation International Neurofibromatosis Meeting is the premier venue for connecting discovery, translational and clinical scientists who are focused on neurofibromatosis types 1 and 2 (NF1 and NF2) and schwannomatosis (SWN). The meeting also features rare tumors such as glioma, meningioma, sarcoma, and neuroblastoma that occur both within these syndromes and spontaneously; associated with somatic mutations in NF1, NF2, and SWN. The meeting addresses both state of the field for current clinical care as well as emerging preclinical models fueling discovery of new therapeutic targets and discovery science initiatives investigating mechanisms of tumorigenesis. Importantly, this conference is a forum for presenting work in progress and bringing together all stakeholders in the scientific community. A highlight of the conference was the involvement of scientists from the pharmaceutical industry who presented growing efforts for rare disease therapeutic development in general and specifically, in pediatric patients with rare tumor syndromes. Another highlight was the focus on new investigators who presented new data about biomarker discovery, tumor pathogenesis, and diagnostic tools for NF1, NF2, and SWN. This report summarizes the themes of the meeting and a synthesis of the scientific discoveries presented at the conference in order to make the larger research community aware of progress in the neurofibromatoses.

Ketotifen suppression of NF1 neurofibroma growth over 30 years.

A patient with NF1 was treated with oral ketotifen for 30 years since infancy. Review of the patient's course and treatment details establishes a basis for reconsideration of several fundamental precepts about NF1 pathogenesis. The data suggest a distinctive benefit to treating an NF1 patient with an inhibitor of mast cell degranulation before cutaneous neurofibromas are clinically apparent: the neurofibromas appear to be arrested at a very early stage of development. The patient's skin was especially remarkable for both the paucity of cutaneous neurofibromas and the distinctive monotonous uniformity of those present, which were small and flat or barely sessile. While the data do not, of themselves, prove that ketotifen treatment commencing in childhood preempts neurofibroma maturation, in the context of earlier publications, they certainly warrant further investigation.

Recent developments in neurofibromatoses and RASopathies: management, diagnosis and current and future therapeutic avenues.

Neurofibromatosis type 1 (NF1) was the first RASopathy and is now one of many RASopathies that are caused by germline mutations in genes that encode components of the Ras/mitogen-activated protein kinase (MAPK) pathway. Their common underlying pathogenetic etiology causes significant overlap in phenotypic features which includes craniofacial dysmorphology, cardiac, cutaneous, musculoskeletal, GI and ocular abnormalities, and a predisposition to cancer. The proceedings from the symposium "Recent Developments in Neurofibromatoses (NF) and RASopathies: Management, Diagnosis and Current and Future Therapeutic Avenues" chronicle this timely and topical clinical translational research symposium. The overarching goal was to bring together clinicians, basic scientists, physician-scientists, advocate leaders, trainees, students and individuals with Ras pathway syndromes to discuss the most state-of-the-art basic science and clinical issues in an effort to spark collaborations directed towards the best practices and therapies for individuals with RASopathies.

The importance of advanced parental age in the origin of neurofibromatosis type 1.

Von Recklinghausen neurofibromatosis (NF1) is an autosomal dominant disorder with a prevalence about 1/3,000 (1/2,000-1/5,000 in various population-based studies). About 30-50% of cases are sporadic, resulting from a new mutation. NF1 is fully penetrant by mid-childhood, stigmata, and medical problems (neurological, dermatological, endocrine, ophthalmological, oncological) are highly variable. Advanced paternal age (APA) has been known to increase the risk of new germline mutations that contribute to the presence of a variety of genetic diseases in the human population. The trend in developed countries has been toward higher parental age due to various reasons. In a cross-sectional study, in two university hospital centers, data on parental age of 103 children (41 female) born between 1976 and 2005 with sporadic NF1 were analyzed. Parental age at birth was compared with the Czech general population matched to birth year. The mean NF1 sporadic case paternal age at birth was 32.0 years (95% CI 30.7-33.3 years) compared with 28.8 years (95% CI 28.6-29.1 years) in the general population (P < 0.001). The mean maternal age at birth was 27.4 years (95% CI 26.3-28.5 years) compared with 25.8 years (95% CI 25.5-26.0 years) in the general population (P < 0.05). The case-control difference in the father's age was higher than it was for the mother's age. Sporadic NF1 cases accounted for 35.6% of our entire NF1 cohort. We confirmed an association of advanced parental and particularly paternal age with the occurrence of sporadic NF1.

Head circumference and anthropometric changes and their relation to plexiform and skin neurofibromas in sporadic and familial neurofibromatosis 1 Brazilian adults: a cross-sectional study.

BACKGROUND: Neurofibromatosis 1 (NF1) is a common autosomal dominant syndrome with complete penetrance and highly variable expressivity. The cutaneous neurofibroma (Cnf) and plexiform neurofibroma (Pnf), café-au-lait spots, and freckle-like lesions are common in NF1, but many other manifestations can occur. We aimed to evaluate head circumference, height, weight, body mass index (BMI), head circumference-to-height ratio (HCHR) and waist-hip ratio (WHR) in adult NF1 Brazilian individuals versus a paired control group and investigate their correlation with the presence of clinically visible Pnfs, and number of "skin neurofibromas" (Snf), which include both cutaneous and subcutaneous neurofibromas. METHODS: A case-control study was conducted with 168 individuals, 84 with NF1 and 84 without NF1, paired by sex and age. Head circumference and anthropometric measurements, Snf quantification, evaluation of clinically visible Pnf and familial inheritance were accessed. RESULTS: Prevalence of macrocephaly was significantly higher in NF1 women. Height and weight were significantly lower in both males and females with NF1. HCHR was higher in the NF1 group than in the control group for both sexes. BMI was significantly lower in men with NF1. Waist and hip circumferences were significantly reduced in NF compared with the controls, but the mean WHR was significantly lower only in NF1 women. No correlation was found between the Snf and head circumference and anthropometric measurements, sex or family history. The presence and larger size of clinically visible plexiform neurofibromas were associated with normal stature (p = 0.037 and p = 0.003, respectively). CONCLUSIONS: NF1 individuals have increased prevalence of macrocephaly, short stature, low BMI, and reduced abdominal fat. There is no relation between head circumference and anthropometric data with family history, or neurofibromas.

S100B and neurofibromin immunostaining and X-inactivation patterns of laser-microdissected cells indicate a multicellular origin of some NF1-associated neurofibromas.

Neurofibromatosis 1 (NF1) is an autosomal dominant disease that predisposes individuals to developing benign neurofibromas. Some features and consequences of NF1 appear to result from partial deficiency of neurofibromin (Nfn), the NF1 gene protein product, as a result of haploinsufficiency for the NF1 gene. Other features and consequences of NF1 appear to involve total deficiency of Nfn, which arises as a result of either loss of function of the second NF1 allele or excess degradation of Nfn produced by the second allele in a particular clone of cells. We used immunofluorescence to assess the presence of Nfn in putative Schwann cells (S100B(+) ) and non-Schwann cells (S100B(-) ) in 36 NF1-derived benign neurofibromas classified histologically as diffuse or encapsulated. The S100B(+) /Nfn(-) cell population made up only 18% ± 10% (mean ± standard deviation) of the neurofibroma cells in both the diffuse and encapsulated neurofibromas. The proportion of S100B(+) /Nfn(+) cells was significantly higher and the proportion of S100B(-) /Nfn(-) cells was significantly lower in diffuse neurofibromas than in encapsulated neurofibromas. We isolated S100B(+) /Nfn(+) , S100B(+) /Nfn(-) , and S100B(-) /Nfn(+) cells by laser microdissection and, using X-chromosome inactivation profiles, assessed clonality for each cell type. We showed that, although some neurofibromas include a subpopulation of S100B(+) /Nfn(-) cells consistent with clonal expansion of a Schwann cell progenitor that has lost function of both NF1 alleles, other neurofibromas do not show evidence of monoclonal proliferation of Schwann cells. Our findings suggest that, although clonal loss of neurofibromin function is probably involved in the development of some NF1-associated neurofibromas, other pathogenic processes also occur.

Structural alteration of lung parenchyma in patients with NF1: a phenotyping study using multidetector computed tomography (MDCT).

BACKGROUND: Diffuse interstitial lung disease have been described in Neurofibromatosis type 1 (NF1), but its diversity and prevalence remain unknown. The aim of this study was to assess the prevalence and characteristics of (NF1)-associated lung manifestations in a large single-center study using multidetector computed tomography (MDCT) and to evaluate the smoking history, patients' age, genetics, and the presence of malignant peripheral nerve sheath tumors (MPNST) as potential influencing factors for lung pathologies. METHODS: In this retrospective study, 71 patients with NF1 were evaluated for the presence of distinctive lung manifestations like reticulations, consolidations, type of emphysema, pulmonary nodules and cysts. All patients underwent F-18-FDG PET/CT scans, which were reviewed by two experienced radiologists in consensus. Patients' subgroups were formed based on their smoking history (current smokers/previous smokers/never smokers), age (< 12 years, 12-18 years, > 18 years), and presence of MPNST (MPNST/no MPNST). In 57 patients (80%), genetic analysis of sequences coding for the neurofibromin on chromosome 17 was performed, which was correlated with different lung pathologies. RESULTS: Among all NF1 patients (33 ± 14 years, 56% females), 17 patients (24%) were current smokers and 62 patients (87%) were > 18 years old. Pulmonary cysts, nodules, and paraseptal emphysema were the most common pulmonary findings (35%, 32%, 30%). The presence of pulmonary metastases, MPNST and centrilobular emphysema was associated with smoking. Cysts were observed only in adults, whereas no significant correlation between age and all other pulmonary findings was found (p > 0.05). Presence of MPNST was accompanied by higher rates of intrapulmonary nodules and pulmonary metastasis. Neither the presence nor absence of any of the specific gene mutations was associated with any particular lung pathology (p > 0.05). CONCLUSIONS: All pulmonary findings in NF1 patients occurred independently from specific mutation subtypes, suggesting that many NF1 mutations can cause various pulmonary pathologies. The presence of pulmonary metastases, MPNST and centrilobular emphysema was associated with smoking, indicating the value of smoking secession or the advice not to start smoking in NF1 patients as preventive strategy for clinicians. For screening of pulmonary manifestations in NF1 patients, an MDCT besides medical history and physical examination is mandatory in clinical routine.

Neurofibromin Deficiency and Extracellular Matrix Cooperate to Increase Transforming Potential through FAK-Dependent Signaling.

Plexiform neurofibromas (Pnfs) are benign peripheral nerve sheath tumors that are major features of the human genetic syndrome, neurofibromatosis type 1 (NF1). Pnfs are derived from Schwann cells (SCs) undergoing loss of heterozygosity (LOH) at the NF1 locus in an NF1+/- milieu and thus are variably lacking in the key Ras-controlling protein, neurofibromin (Nfn). As these SCs are embedded in a dense desmoplastic milieu of stromal cells and abnormal extracellular matrix (ECM), cell-cell cooperativity (CCC) and the molecular microenvironment play essential roles in Pnf progression towards a malignant peripheral nerve sheath tumor (MPNST). The complexity of Pnf biology makes treatment challenging. The only approved drug, the MEK inhibitor Selumetinib, displays a variable and partial therapeutic response. Here, we explored ECM contributions to the growth of cells lacking Nfn. In a 3D in vitro culture, NF1 loss sensitizes cells to signals from a Pnf-mimicking ECM through focal adhesion kinase (FAK) hyperactivation. This hyperactivation correlated with phosphorylation of the downstream effectors, Src, ERK, and AKT, and with colony formation. Expression of the GAP-related domain of Nfn only partially decreased activation of this signaling pathway and only slowed down 3D colony growth of cells lacking Nfn. However, combinatorial treatment with both the FAK inhibitor Defactinib (VS-6063) and Selumetinib (AZD6244) fully suppressed colony growth. These observations pave the way for a new combined therapeutic strategy simultaneously interfering with both intracellular signals and the interplay between the various tumor cells and the ECM.

A Clinicopathologic Study on the Role of Estrogen, Progesterone, and Their Classical and Nonclassical Receptors in Cutaneous Neurofibromas of Individuals With Neurofibromatosis 1.

OBJECTIVES: To evaluate the expression of progesterone receptor (PR), estrogen receptor (ER), and G protein-coupled estrogen receptor 1 (GPER-1) in cutaneous neurofibromas (cNFs) and their correlation with demographic, clinical, and laboratory data of individuals with neurofibromatosis 1 (NF1). The association of PROGINS polymorphism and PR expression in cNFs, as well as the serum steroidal hormones and the number of cNFs, was investigated. METHODS: The sample comprised 80 large and 80 small cNFs from 80 individuals with NF1. PR, ER, GPER-1, and Ki-67 expression were investigated by immunohistochemistry in tissue micro- and macroarrays and quantified using a digital computer-assisted method. The number of cNFs, the levels of serum 17ß estradiol and progesterone, and the PROGINS polymorphism were identified. RESULTS: Twelve (8.5%) small cNFs were weakly positive for ER, 131 (92.3%) cNFs expressed PR, and all (100%) cNFs expressed GPER-1. Large cNFs showed a higher expression of PR (P < .0001) and GPER-1 (P = .019) and had a higher intensity of staining for these receptors (P < .0001). The cell proliferation index was positively correlated with PR (P = .001). Persons with more cNFs had higher serum levels of progesterone (P = .001). CONCLUSIONS: These findings emphasize the role of estrogen and progesterone in cNF development and suggest that these hormones may act on cNF cells via a noncanonical pathway through GPER-1.

Neurofibromatosis type 1 is a disorder of dysplasia: the importance of distinguishing features, consequences, and complications.

BACKGROUND: The disorder neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene, which influences the availability of activated Ras and the latter's control of cellular proliferation. Emphasis on this aspect of NF1 has focused attention on the tumor suppression function of NF1 and thereby displaced attention from the gene's role in initial normal tissue formation, maintenance, and repair. METHODS: Clinical and neuroimaging data systematically compiled over more than 30 years are analyzed to document the involvement of multiple organs and tissues, often with an embryonic origin. In addition, recent literature based on selective knockout mouse experiments is cited to corroborate embryonic dysplasia as an element of NF1 pathogenesis. RESULTS: Tissue dysplasia, both ab initio and as part of tissue maintenance and wound healing, is a key clinical and pathogenetic aspect of NF1 and thereby provides a rationale for differentiating the elements of NF1 into features, consequences, and complications. CONCLUSIONS: NF1 is a histogenesis control gene that also has properties that overlap with those of a tumor suppressor gene. Both its neoplastic and dysplastic manifestations become more amenable to understanding and treatment if they are differentiated at three levels--specifically, features, consequences and complications.

The evolution and multi-molecular properties of NF1 cutaneous neurofibromas originating from C-fiber sensory endings and terminal Schwann cells at normal sites of sensory terminations in the skin.

In addition to large plexiform neurofibromas (pNF), NF1 patients are frequently disfigured by cutaneous neurofibromas (cNF) and are often afflicted with chronic pain and itch even from seemingly normal skin areas. Both pNFs and cNF consist primarily of benign hyperproliferating nonmyelinating Schwann cells (nSC). While pNF clearly arise within deep nerves and plexuses, the role of cutaneous innervation in the origin of cNF and in chronic itch and pain is unknown. First, we conducted a comprehensive, multi-molecular, immunofluorescence (IF) analyses on 3mm punch biopsies from three separate locations in normal appearing, cNF-free skin in 19 NF1 patients and skin of 16 normal subjects. At least one biopsy in 17 NF1 patients had previously undescribed micro-lesions consisting of a small, dense cluster of nonpeptidergic C-fiber endings and the affiliated nSC consistently adjoining adnexal structures-dermal papillae, hair follicles, sweat glands, sweat ducts, and arterioles-where C-fiber endings normally terminate. Similar micro-lesions were detected in hind paw skin of mice with conditionally-induced SC Nf1-/- mutations. Hypothesizing that these microlesions were pre-cNF origins of cNF, we subsequently analyzed numerous overt, small cNF (s-cNF, 3-6 mm) and discovered that each had an adnexal structure at the epicenter of vastly increased nonpeptidergic C-fiber terminals, accompanied by excessive nSC. The IF and functional genomics assays indicated that neurturin (NTRN) and artemin (ARTN) signaling through cRET kinase and GFRα2 and GFRα3 co-receptors on the aberrant C-fiber endings and nSC may mutually promote the onset of pre-cNF and their evolution to s-cNF. Moreover, TrpA1 and TrpV1 receptors may, respectively, mediate symptoms of chronic itch and pain. These newly discovered molecular characteristics might be targeted to suppress the development of cNF and to treat chronic itch and pain symptoms in NF1 patients.