Clinical Diagnosis Of Neurofibromatosis Type 1 Research Articles

Prevalence of neurofibromatosis type 1 in patients presenting with neurofibromas of the eyelid and orbit

Abstract Aims: This study aimed to demonstrate the prevalence of neurofibromatosis type 1 diagnosis in patients presenting with neurofibromas of eyelid and orbit and the factors associated with this disease. Materials and Methods: Charts from patients with pathology reports of neurofibroma of the eyelid and orbit from the MUHC-McGill University Ocular Pathology Laboratory from 2007 to 2022 were reviewed to find information about clinical diagnosis of neurofibromatosis type (NF) 1, sex, age, presence of Lisch nodules, and other findings. The data were analyzed with the Chi-square test and Fisher’s exact test. Results: The prevalence of NF1 in patients presenting neurofibromas of the eyelid and orbit was 47.62% in the population studied. All patients with plexiform neurofibromas and all the ones presenting Lisch nodules had an NF1 diagnosis. Conclusion: All patients with plexiform neurofibromas of the eyelid or orbit and their relatives should be investigated for NF1. Ophthalmological evaluation is essential for the identification of Lisch nodules since their presence, associated with two neurofibromas are enough to meet the criteria for NF1; therefore, the family of patients with that presentation should be clinically, and if necessary, genetically tested.

Not Only RET but NF1 and Chromosomal Instability Are Seen in Young Patients with Sporadic Medullary Thyroid Carcinoma.

Genetic analysis of sporadic medullary thyroid carcinoma (MTC) has revealed somatic variants in RET, RAS, and occasionally other genes. However, around 20% of patients with sporadic MTC lack a known genetic driver. To uncover potential new somatic or germline drivers, we analyze a distinct cohort of patients with sporadic, very early-onset, and aggressive MTC. Germline and somatic DNA exome sequencing was performed in 19 patients, previously tested negative for germline RET variants. Exome sequencing of 19 germline samples confirmed the absence of RET and identified an NF1 pathogenic variant in 1 patient. Somatic sequencing was successful in 15 tumors revealing RET variants in 80%, predominantly p.Met918Thr, which was associated with disease aggressiveness. In RET-negative tumors, pathogenic variants were found in HRAS and NF1. The NF1 germline and somatic variants were observed in a patient without a prior clinical diagnosis of neurofibromatosis type 1, demonstrating that the loss of heterozygosity of NF1 functions as a potential MTC driver. Somatic copy number alterations analysis revealed chromosomal alterations in 53.3% of tumors, predominantly in RET-positive cases, with losses in chromosomes 9 and 22 being the most prevalent. This study reveals that within a cohort of early-onset nonhereditary MTC, RET remains the major driver gene. In RET-negative tumors, NF1 and RAS are drivers of sporadic MTC. In addition, in young patients without a RET germline mutation, a careful clinical evaluation with a consideration of germline NF1 gene analysis is ideal to exclude Neurofibromatosis type 1 (NF1).

CONCENTRIC MACULAR RINGS SIGN IN COMBINED HAMARTOMA OF RETINA AND RETINAL PIGMENT EPITHELIUM.

To describe two cases of concentric macular rings (CMR) sign in patients with combined hamartoma of retina and retinal pigment epithelium (CHRRPE). History and clinical examination, spectral-domain optical coherence tomography (SD-OCT), and optic coherence tomography angiography (OCTA). The first patient was a 26-year-old woman with clinical diagnosis of Neurofibromatosis type 2. The Best-Corrected Visual Acuity (BCVA) was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). She presented a subtle grayish lesion in the macular region of OD. On macular SD-OCT, there was a thickened and disorganized retina, suggestive of CHRRPE. In addition, at the parafoveal region, there was a dentate pattern in the outer plexiform layer (OPL) and Henle fiber layer (HFL) on cross-sectional SD-OCT. OCTA showed no foveal avascular zone (FAZ) in OD and Optos ultra-wide-field revealed CMR sign in this eye. The second patient was a 14-year-old boy, with diabetes mellitus type 1. His BCVA was 20/25 in OD and 20/20 in OS. He had a subtle whitish lesion in the macular region of OD, with SD-OCT findings suggestive of CHRRPE. Similar to the first case, there was a dentate pattern in the OPL and HFL, on SD-OCT. In OD, blue reflectance images exhibited the CMR sign, and OCTA showed absent FAZ. CHRRPE may be related to changes in the OPL and HFL interface and may present the CMR sign.

Deciphering the Immune Microenvironment of NF1-associated Peripheral Nerve Sheath Tumors: Identifying Early Biomarkers of Disease Progression and Malignant Transformation

Background/Objective:Neurofibromatosis type 1 (NF1) is a multisystem disorder that affects ~1/3000 newborns. Plexiform neurofibromas (PN) are present in about half of cases and can transform (lifetime risk of 8-13%) into malignant peripheral nerve sheath tumor (MPNST), a highly aggressive and metastatic sarcoma with poor survival. Unfortunately, there are currently no reliable biomarkers to identify PN at risk of undergoing malignant transformation. Our research has revealed that a subset of benign-appearing and atypical PN exhibit deregulated immune surveillance and T-cell infiltration that precede malignant transformation. In this study, we are analyzing tumor microenvironment and immune landscape in NF1-related tissue specimens to identify biomarkers of disease progression. To power these studies, this project focused on constructing a dataset of NF1-related samples to be analyzed.
 Methods:701 patients were identified via Cerner billing codes and pathology archives. De-identified clinical data, including presenting symptoms, relevant clinical history, pathology diagnoses, disease features, prior chemotherapeutics/radiation, prior gene profiling, and imaging features were collected.
 Results: We selected 86 patients with a total of 175 samples. 81% of patients had a clinical diagnosis of NF1, and 6% had a history of MPNST. Out of the 175 samples, 54 were in the head and neck, 42 in the thorax, 28 in the lower extremity, 27 in the upper extremity, 26 in the pelvis/abdomen, and 15 in the paraspinal region. The leading causes of procedures were pain (41%), growth (40%), and concern for malignancy (27%). The most common tissue diagnoses were neurofibroma (51.4%), PN (20%), and undefined-grade MPNST (11%). Out of the 46 MPNSTs, 30 were primary tumors, 4 metastases, and 12 local recurrences.
 Conclusion and Potential Impact:The results of this study will provide valuable insights to inform preclinical models of NF1-tumorigenesis to validate these findings and identify novel treatment approaches for individuals affected by these rare but devastating tumors.

P11.43.B HIGH-RESOLUTION NERVE ULTRASOUND IN NEUROFIBROMATOSIS TYPE 1

Abstract BACKGROUND Patients with neurofibromatosis type 1 (NF1) can develop plexiform neurofibromas (PN). PN are peripheral nerve sheath tumors that can cause pain, neurological deficit and can transform into malignant peripheral nerve sheath tumors (MPNST). High-resolution ultrasound (HRUS) is suggested as a quick and cost-effective technique, as compared to whole-body MRI, for screening NF1 patients for PN. Our aim is to describe the variety of HRUS nerve abnormalities in NF1 patients and to study the link between nerve morphology and nerve function. MATERIAL AND METHODS We selected patients with a clinical diagnosis of NF1, with or without symptoms related to the peripheral nervous system (PNS) such as pain, sensory disturbances or loss of strength. Patients were invited for a study visit including neurological examination, nerve conduction studies (NCS) and HRUS. One-sided NCS were performed of the median and ulnar nerve (motor and sensory), peroneal and tibial nerve (motor) and sural nerve according to standard protocol. We visualised the brachial plexus, median-, radial-, ulnar-, peroneal-, tibial-, and sural nerves on both sides using HRUS. The cross-sectional area (CSA) of the nerve was measured at predefined anatomical sites, and additional sites in case of focal nerve enlargement. RESULTS We enrolled 60 NF1 patients, of which 57% had PNS-related symptoms. One third of our patients had neurological deficits during physical examination. We found nerve enlargement with HRUS in 48 out of 60 patients (80%), this was not significantly different between patients with PNS symptoms or without PNS symptoms (82% vs 77% respectively, p=0.602). In 82% of the patients with PNS symptoms, their symptoms were likely to be related to one or more nerve enlargements. Nine of these patients had clinical and neurophysiological signs of carpal tunnel syndrome. Different patterns of nerve enlargement were identified. 46% had isolated nerve enlargements, 25% had diffusely enlarged nerves and 29% had a mixture of diffusely enlarged nerves with isolated nerve enlargements. The majority of the patients with nerve enlargement on HRUS had no abnormalities on NCS (65%). CONCLUSION The majority of NF1 patients have nerve enlargements as seen by HRUS, however we have shown that nerve enlargements can often be asymptomatic and do not always lead to impaired nerve function. To determine whether patients have PN cannot be based solely on clinical evaluation of symptoms. HRUS might have an application as a screening tool for NF1 patients in clinical practice. However, further research is needed to describe growth of nerve enlargements, the impact of intra- and interobserver variability on CSA measurements and to improve our knowledge on the link between nerve morphology and nerve function in NF1.

Neurofibromatosis type 1, from gene mutation to clinical presentation

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with a prevalence of about1/3000. The clinical diagnosis of NF1 is based on the presence of two or more of the followingcriteria: six or more café au lait spots, >2 neurofibromas of any type, freckling in the axillary oringuinal region, optic glioma, a distinctive osseous lesion such as sphenoid dysplasia or thinning oflong bone cortex with or without pseudoarthrosis, and a first degree relative with NF1.We report A 7-year-old male with multiple café au lait spots diagnosed with Neurofibromatosisin Kigali-Rwanda by using next-generation sequencing and copy number variation analysis, thepatient presented with painless nodular skin lesions that first developed 4 years earlier. Skinnodules initially appeared on the anterior chest wall and progressed to the posterior chest wallextending to the axilla region. His medical history and that of his family were unremarkable. To ourknowledge, this is the first case to be diagnosed using this technology; The disease has numerouscomplications. The mutation rate for NF1-gene is high; 50% of all cases of NF1 are from newmutations. The gene protein product - neurofibromin plays an important role in tumor genesis asa tumor-suppressor gene.Combining both clinical findings and molecular genetic evaluation to identify disease-causingmutations is paramount in confirming the diagnosis. Patient care is best done in a multidisciplinarysetting approach for proper patient satisfaction and better prediction of future prognosis.

Primary pilocytic astrocytoma of the cerebellopontine angle in pediatric patient with neurofibromatosis type 1: a case report

BackgroundCerebellopontine angle tumor (CPA) in pediatrics is rare as compared to adults. We describe a case of pediatric pilocytic astrocytoma presented as a right CPA mass with a concurrent clinical diagnosis of neurofibromatosis type 1 (NF1).Case presentationA 14-year-old boy with a newly diagnosed hypertension presented with a short history of headache and blurring vision. Neurological examination revealed bilateral papilloedema, partial right third nerve palsy and mild sensorineuronal hearing deficits. Skin examination identified multiple café au lait spots with cutaneous neurofibromas. Preoperative neuroimaging suggested the diagnosis of an extraaxial CPA mass consistent with meningioma, with obstructive hydrocephalus. A left ventriculoperitoneal shunt was inserted and the child was subjected for a suboccipital retrosigmoid approach for tumor resection. The histopathological features, however, were typical for pilocytic astrocytoma.ConclusionsA careful evaluation of the clinical presentation and radiological images of CPA lesions is necessary prior to surgical embarkment. To the best of our knowledge, this case is the first report of pilocytic astrocytoma in the CPA in pediatric with NF1.

A Retrospective Chart Review of Children in Neurocutaneous Clinic Who May Benefit from Further Evaluation Beyond Neurofibromatosis Type I

While most individuals with a clinical diagnosis of Neurofibromatosis type 1 (NF1) have a detectable pathogenic variant in the NF1 gene, other conditions have phenotypic features overlapping with NF1. Without molecular confirmation, individuals may be misdiagnosed and have a different underlying condition. Namely, if a child has constitutional mismatch repair deficiency (CMMRD), early detection and prevention strategies for cancer risk would include surveillance recommendations not typically recommended for children with NF1. This study aimed to explore phenotypes of individuals with a clinical diagnosis of NF1 to identify subpopulations who may benefit from further genetic counseling or testing for an alternate diagnosis. Retrospective review of 240 medical records of children who attended a neurocutaneous clinic identified 135 children with a molecularly confirmed pathogenic variant in NF1 or autosomal dominant pattern of clinical NF1 ('controls') and 102 children deemed 'at-risk' for another condition like CMMRD. Clinical presentation, family history of NF1, personal history of cancer, and family history of cancer were compared. When comparing clinical presentation, family history, and cancer history, minimal statistical differences were found, indicating that the at-risk population appears clinically indistinguishable from those with a clear diagnosis of NF1. Given the lack of distinguishable features between the at-risk and control population, this study suggests that tiered genetic testing for all individuals being evaluated for NF1 may be beneficial for identifying patients who may be misdiagnosed with NF1 and subsequently mismanaged.

Clinical diagnosis of neurofibromatosis type I in multiple family members due to cosegregation of a unique balanced translocation with disruption of the NF1 locus: Testing considerations for accurate diagnosis

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder that causes a predisposition to develop tumors along the peripheral nervous system. The NF1 gene, located at 17q11.2, has the highest mutation rate among known human genes and about half of NF1 patients have de novo pathogenic variants. We present a case of clinical NF1 diagnoses in multiple family members with phenotypes ranging from mild to severe. Chromosome analysis of the 3-year-old female proband with NF1 resulted in an abnormal karyotype that was inherited from her mother: 46,XX,t(4;17)(q21.3;q11.2) mat. However, no NF1 genetic variants were identified by either NGS analysis of NF1 DNA coding regions, deletion-duplication studies, or by cytogenomic microarray copy number analysis. Follow-up chromosome studies of the proband's two male siblings demonstrated cosegregation of the same balanced translocation and a clinical diagnosis of NF1. Based on the cosegregation of the translocation with the NF1 clinical presentation in this family, we hypothesized that the NF1 gene may have been disrupted by this unique rearrangement. Subsequent fluorescence in situ hybridization (FISH) analysis of the metaphase cells of an affected sibling revealed a disruption of the NF1 gene confirming the underlying basis of the clinical NF1 presentation in this family. The utilization of traditional cytogenetic as well as evolving molecular methods was not only pivotal in the diagnosis of NF1 and management for this family, but is also pertinent to other patients with a family history of NF1.

Ocular alterations, molecular findings, and three novel pathological mutations in a series of NF2 patients.

To evaluate ophthalmological and molecular findings in eight patients with a clinical diagnosis of neurofibromatosis type 2 (NF2). New pathological mutations are described and variability in the ophthalmic phenotype and NF2 allelic heterogeneity are discussed. Eye examination was performed in eight NF2 patients, and it included the measurement of the visual acuity, biomicroscopy, dilated fundus examination, color fundus photography, infrared photography, and spectral domain optical coherence tomography (SD-OCT). Molecular analysis was performed with whole-exome sequencing using DNA derived from peripheral blood mononuclear cells from each individual. Ophthalmological features were present in all patients, ranging from subtle retinal alterations identified only using SD-OCT to severe ocular damage present at birth. Six mutations were observed: two patients with stop codon mutation as shown on table 1 and result section, three patients with frameshift mutation as shown on table 1 and result section. Three novel mutations were found among them. It is a descriptive study of a rare disease, with poor previous literature. Clinical and genetic data are shown, reviving the need to further studies to clarify the genotype-phenotype correlations in NF2.

Height Growth Impairment in Children With Neurofibromatosis Type 1 Is Characterized by Decreased Pubertal Growth Velocity in Both Sexes.

Previous studies have suggested that children with neurofibromatosis type 1 are shorter than their unaffected counterparts as an effect of a germline NF1 gene mutation. The pathophysiology of this effect is still uncertain. The purpose of this study was to characterize longitudinal growth in children with neurofibromatosis type 1 in order to assess growth velocity and its influence on stature. Longitudinal height data were collected for 188 patients with a confirmed clinical diagnosis of neurofibromatosis type 1. Children with neurofibromatosis type 1 had population mean heights statistically different from the general population, with a reduced peak height velocity during pubertal growth. In addition, there were no significant differences in the timing of peak height velocity during puberty between the general population and those with neurofibromatosis type 1. These data demonstrate that short stature in neurofibromatosis type 1 is due in part to subnormal height acquisition during puberty.

Thyroid Gland 18F-FDG Uptake in Neurofibromatosis Type 1

Purpose: To investigate thyroid gland characteristics on ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) imaging in patients with neurofibromatosis type 1 (NF1). Subjects and Methods: Thyroid gland characteristics of patients with a clinical diagnosis of NF1 who underwent ¹⁸F-FDG PET/CT imaging for the first time to distinguish benign neurofibroma from malignant peripheral nerve sheath tumor (MPNST) at our institution (n = 69) were compared to PET/CT imaging of sarcoidosis (n = 25) and early stage lung cancer (T₁N₀M₀ tumors, n = 15) patients. Results: Two NF1 patients (3%) showed a diffuse ¹⁸F-FDG uptake in the thyroid gland, 2 patients (3%) had an irregular uptake, and 7 patients (10%) had a focal uptake. Among the sarcoidosis patients, 1 showed a diffuse uptake (4%) and 1 had an irregular uptake (4%). In the early stage lung cancer group, 1 patient showed a diffuse uptake (7%) and 1 had a focal uptake (7%). NF1 patients had larger mean thyroid volume and mean SUV_max compared to sarcoidosis patients but not compared to early stage lung cancer patients. Four NF1 patients were diagnosed with multinodular goiter, 2 patients were diagnosed with benign chronic lymphocytic thyroiditis, 1 patient had metastasis to the thyroid, and 1 patient had medullary thyroid cancer. Conclusion: Even though NF1 patients did not show an increased risk of thyroid incidentaloma on PET/CT compared to previous studies on non-thyroid cancer patients, the incidence shows that awareness of possible thyroid disease is important.

Children with 5'-end NF1 gene mutations are more likely to have glioma.

Objective:To ascertain the relationship between the germline NF1 gene mutation and glioma development in patients with neurofibromatosis type 1 (NF1).Methods:The relationship between the type and location of the germline NF1 mutation and the presence of a glioma was analyzed in 37 participants with NF1 from one institution (Washington University School of Medicine [WUSM]) with a clinical diagnosis of NF1. Odds ratios (ORs) were calculated using both unadjusted and weighted analyses of this data set in combination with 4 previously published data sets.Results:While no statistical significance was observed between the location and type of the NF1 mutation and glioma in the WUSM cohort, power calculations revealed that a sample size of 307 participants would be required to determine the predictive value of the position or type of the NF1 gene mutation. Combining our data set with 4 previously published data sets (n = 310), children with glioma were found to be more likely to harbor 5′-end gene mutations (OR = 2; p = 0.006). Moreover, while not clinically predictive due to insufficient sensitivity and specificity, this association with glioma was stronger for participants with 5′-end truncating (OR = 2.32; p = 0.005) or 5′-end nonsense (OR = 3.93; p = 0.005) mutations relative to those without glioma.Conclusions:Individuals with NF1 and glioma are more likely to harbor nonsense mutations in the 5′ end of the NF1 gene, suggesting that the NF1 mutation may be one predictive factor for glioma in this at-risk population.

Validation of a Next-Generation Sequencing Pipeline for the Molecular Diagnosis of Multiple Inherited Cancer Predisposing Syndromes

Despite the growing knowledge of the genetic background behind the cancers that occur in a context of hereditary predisposition, personal or family cancer history may not be clear enough to support directional gene testing. Defined targeted next-generation sequencing gene panels allow identification of the causative disease mutations of multigene syndromes and differential diagnosis for syndromes with phenotypically overlapping characteristics. Herein, we established a next-generation sequencing analysis pipeline for the molecular diagnosis of multiple inherited cancer predisposing syndromes using the commercially available target sequencing panel TruSight Cancer. To establish the analysis pipeline, we included 22 control samples with deleterious mutations covering all genes currently analyzed at our institution by standard Sanger sequencing. We tested the pipeline using 51 samples from patients with a clinical diagnosis of neurofibromatosis type 1 (NF1), 10 of which without previous molecular characterization of the causative NF1 mutations. We propose a thoroughly validated analysis pipeline that combines Isaac Enrichment, Burrows-Wheeler Aligner Enrichment, and NextGENe for the alignment and variant calling, and GeneticistAssistant for variant annotation and prioritization. This pipeline allowed the identification of disease-causing mutations in all 73 patients, including a large duplication of 37 bp in NF1. We show that high sensitivity and specificity can be achieved by using multiple bioinformatic tools for alignment and variant calling and careful variant filtering, having in mind the clinical question.

Importance and necessity of extended molecular diagnostic – Confirmation of the clinical diagnosis of neurofibromatosis type 1

Importance and necessity of extended molecular diagnostic – Confirmation of the clinical diagnosis of neurofibromatosis type 1

P.Arg1809Cys substitution in neurofibromin is associated with a distinctive NF1 phenotype without neurofibromas.

Analysis of 786 NF1 mutation-positive subjects with clinical diagnosis of neurofibromatosis type 1 (NF1) allowed to identify the heterozygous c.5425C>T missense variant (p.Arg1809Cys) in six (0.7%) unrelated probands (three familial and three sporadic cases), all exhibiting a mild form of disease. Detailed clinical characterization of these subjects and other eight affected relatives showed that all individuals had multiple cafè-au-lait spots, frequently associated with skinfold freckling, but absence of discrete cutaneous or plexiform neurofibromas, Lisch nodules, typical NF1 osseous lesions or symptomatic optic gliomas. Facial features in half of the individuals were suggestive of Noonan syndrome. Our finding and revision of the literature consistently indicate that the c.5425C>T change is associated with a distinctive, mild form of NF1, providing new data with direct impact on genetic counseling and patient management.

Neurofibromatose tipo 1: relato de um caso clínico

Introduction: Neurofibromatosis type 1 (NF1) is a common neurocutaneous condition with an autosomal dominant pattern of inheritance. A new mutation occurs in about half of the cases. The diagnosis is based on clinical assessment so family physicians should be aware of the manifestations of the disease. Case presentation: A 29 year-old female patient presented with a history of numerous skin lesions since childhood. The lesions were getting progressively worse. The patient also had learning disabilities. Her mother had similar skin lesions. She was referred to a General Surgery clinic in 2008 because of “multiple moles and warts”. After excision of skin lesions, a pathological diagnosis, of neurofibromas was made in 2009. She was referred to a Neurology clinic and the clinical diagnosis of NF1 was confirmed by the presence of neurofibromas, freckles, and more than 6 cafe au lait spots on the skin. It was also noted that her three year-old son had one cafe au lait patch on his skin. The child was referred to a Dermatology clinic in 2012. At this time the child fulfilled the clinical criteria for the diagnosis of NF1. Commentary: Because of the prevalence (1/2500-3000) and severity of complications of NF1, the early detection of the disease is important. As is evident in this case, clinicians are not always aware of its manifestations, missing opportunities for genetic counselling and preventing complications of the disease.

Abstract P3-08-09: Clinical and Pathological Characteristics of Breast Cancer in Women with Neurofibromatosis Type 1

Abstract Background: Neurofibromatosis type 1(NF1) is an autosomal dominant genetic disorder affecting 1 in 3,000 individuals worldwide. Risk of cancer, including breast cancer, is increased, as NF1 is a tumour suppressor gene. There is limited data on the characteristics of breast cancer in individuals with NF1. Objectives: To study the clinical and pathological characteristics of breast cancer in women with NF1. Methodology: Patients with both NF1 and breast cancer were identified retrospectively from hospital records as well as prospectively when seen at National Cancer Centre Singapore (NCCS) and Singapore General Hospital (SGH). All women had histologically proven breast cancer and fulfilled at least 2 of the 7 criteria developed by the NIH Consensus Conference for clinical diagnosis of NF1. Germline NF1 mutation sequencing is being performed on patients with blood specimens available. Details on patient demographics, tumour grade, stage, receptor status and clinical outcome were evaluated. The pathological characteristics of NF1-associated breast cancer were then compared to sporadic breast cancers in our 2001–2004 cohort, with a focus on grade and HER2 positivity rate. Results: We identified 13 women with NF1 and breast cancer seen at our institutions from 2001 to present date. Average age of breast cancer diagnosis for women testing positive was 48 years (range 30–64). All 13 patients had invasive ductal carcinoma; of which 5 were stage 3 or 4 at diagnosis. To date, 4 out of 12 patients with stage 1–3 breast cancer have relapsed. Grade, estrogen, progesterone and HER2 receptor status were fully available for 12 patients. Ten out of 12 tumours (83%) were grade 3, compared to 45% (705/1578) among our sporadic breast cancers (p = 0.007). Eight out of 12(67%) NF1-associated breast cancers were HER2 positive (IHC 3+ or FISH positive), compared to 27% (367/1367) in sporadic cancers (p = 0.002). Two other NF1-associated tumours were triple negative, and two were hormone receptor positive and HER2 negative. Six out of 12 (50%) NF1-associated cancers were estrogen receptor (ER) positive, compared to 67% (1124/1689) in sporadic cancers (p = 0.2). Conclusion: Our findings suggest that NF1-associated breast cancer tends to be more aggressive, with a higher frequency of grade 3 and HER2 positive tumours compared to sporadic breast cancer. Further genomic profiling of these tumours (in progress) may elucidate the role of NF1 in breast cancer. This may also have implications for sporadic tumours with somatic NF1 mutations in individuals without NF1. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-08-09.

JMML Revisited: Role Und Outcome of Hematopoietic Stem Cell Transplantation in Subtypes of Juvenile Myelomonocytic Leukemia (JMML)

AbstractAbstract 955Hematopoietic stem cell transplantation (HSCT) has improved survival of children with JMML considerably. Since it became apparent that JMML is a heterogeneous disease it has been questioned whether HSCT is the therapy of choice for all subtypes of JMML. Here we report the outcome of children with JMML registered to the retrospective or prospective studies of the European Working Group of MDS and JMML in Childhood (EWOG-MDS) with respect to clinical and mutational subtypes and presence or absence of HSCT. Among the 488 children with JMML studied by EWOG-MDS 43 patients (8.8%) were known to have Noonan syndrome, while 48 (9.7%) carried the clinical diagnosis of neurofibromatosis type 1 (NF1). Mutational analysis was carried out in 254 of the remaining 397 children. Somatic mutations in PTPN11, KRAS and NRAS were seen in 116, 46 and 47 children, respectively; 8 patients were noted to have germline CBL mutations in the absence of Noonan phenotype and 37 children with complete typing (N=203) had none of these abnormalities (all negative group). For the 51 patients with Noonan syndrome and/or germline CBL mutations overall survival at 5 years was 0.72 (0.58-0.86) irrespective whether HSCT was performed or not. A normal karyotype was observed in all but 3 of these 51 children. Normal chromosomal studies were also observed in 74%, 66% and 60% of the NF1, PTPN11 mutated and the all negative group, respectively. Interestingly, monosomy 7, and other aberrations were noted in 52% and 10% of KRAS mutated patients, respectively, but only in 7% and 5% of the NRAS mutated group (P<0.05). Five of the patients with NRAS mutation and normal karyotype are long term survivors without HSCT (5.5 to 27 years after diagnosis) compared to none of the children from the NF1, PTPN11 mutated, KRAS mutated or all negative group. Event-free survival (EFS) following HSCT differed significantly among the mutational groups with 0.38 (0.29-0.49), 0.43 (0.25-0.61), 0.45 (0.24-0.66), 0.69 (0.54-0.84) and 0.72 (0.56-0.88) for children with PTPN11 mutation, NF1, NRAS mutation, KRAS mutation and the all negative group (P<0.01). Likewise, relapse rate varied between 0.41 (PTPN11 mutation), 0.39 (NF1), 0.31 (NRAS mutation), 0.13 (all negative group) and 0.10 (KRAS mutation) (P< 0.01). Multivariate analysis identified mutational type and age at diagnosis as independent prognostic factors for EFS following HSCT. Interestingly, of the 7 children with JMML and NRAS mutation who relapsed post HSCT 5 had a normal karyotype. Considering that other children with JMML sharing the same oncogenic exon 1 mutations in NRAS experienced long-term survival without HSCT these data indicate that a NRAS mutation by itself may not be sufficient to cause lethal disease. Our results also demonstrate that clinical characteristics and outcome following HSCT differ between patients with JMML and oncogenic NRAS and KRAS mutations. Most importantly, we showed that in JMML subtypes with a low relapse incidence following HSCT (KRAS mutated and all negative group) transplant related mortality exceeds the relapse incidence, while in other subtypes (PTPN11 mutations, NF1) leukemic relapse is the most common failure. Current transplant strategies for children with JMML need to be revised to accommodate these differences among mutational subgroups. Disclosures:No relevant conflicts of interest to declare.

BRAFDuplications and MAPK Pathway Activation Are Frequent in Gliomas of the Optic Nerve Proper

Optic pathway gliomas represent a specific subtype of astrocytoma with unique clinicopathologic and biologic properties, but studies of tumors in the optic nerve proper have been hampered by limited tissue availability. We analyzed optic nerve gliomas of 59 patients (median age, 9 years; range, 3 months-66 years; 33 female, 26 male) using formalin-fixed paraffin-embedded material in tissue microarrays. Seven patients had the clinical diagnosis of neurofibromatosis type 1 (NF1). Fluorescence in situ hybridization studies were performed for BRAF, PTEN, CDKN2A (p16), and NF1. Immunohistochemistry was performed for glial fibrillary acidic protein, phospho-ERK, and mutant IDH1 protein. The BRAF duplication was present in 11 (73%) of 15 evaluable tumors, including 1 NF1 patient (1 of 4 tested; 25%). The single tumor lacking BRAF duplication or NF1 association had histologic features of a ganglioglioma. Conversely, heterozygous PTEN deletions were present in 2 (8%) of 25 evaluable cases, one of which was BRAF duplicated and the other was NF1 associated. CDKN2A and NF1 deletions were absent in all tumors tested. Phospho-ERK immunoreactivity was present in 55 (96%) of 57 tumors and was mostly strong and diffuse (80%). Only 1 case of 53 expressed IDH1. Thus, optic nerve gliomas demonstrated molecular alterations typical of pilocytic astrocytomas, including the universal presence of either BRAF duplication or NF1 association and common mitogen-activated protein kinase pathway activation but very rare mutant IDH1 expression.