Plexiform neurofibromas in children with neurofibromatosis type 1: frequency and associated clinical deficits

Towards a neurobiological understanding of pain in neurofibromatosis type 1: mechanisms and implications for treatment

Neurofibromatosis type 1 (NF1) is the most common of a group of rare diseases known by the term, "Neurofibromatosis," affecting 1 in 3000 to 4000 people. NF1 patients present with, among other disease complications, café au lait patches, skin fold freckling, Lisch nodules, orthopedic complications, cutaneous neurofibromas, malignant peripheral nerve sheath tumors, cognitive impairment, and chronic pain. Although NF1 patients inevitably express pain as a debilitating symptom of the disease, not much is known about its manifestation in the NF1 disease, with most current information coming from sporadic case reports. Although these reports indicate the existence of pain, the molecular signaling underlying this symptom remains underexplored, and thus, we include a synopsis of the literature surrounding NF1 pain studies in 3 animal models: mouse, rat, and miniswine. We also highlight unexplored areas of NF1 pain research. As therapy for NF1 pain remains in various clinical and preclinical stages, we present current treatments available for patients and highlight the importance of future therapeutic development. Equally important, NF1 pain is accompanied by psychological complications in comorbidities with sleep, gastrointestinal complications, and overall quality of life, lending to the importance of investigation into this understudied phenomenon of NF1. In this review, we dissect the presence of pain in NF1 in terms of psychological implication, anatomical presence, and discuss mechanisms underlying the onset and potentiation of NF1 pain to evaluate current therapies and propose implications for treatment of this severely understudied, but prevalent symptom of this rare disease.

Current status and recommendations for imaging in neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis

Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN) are three clinically distinct tumor predisposition syndromes with a shared tendency to develop peripheral and central nervous system neoplasms. Disease expression and complications of NF1, NF2, and SWN are highly variable, necessitating a multidisciplinary approach to care in order to optimize outcomes. This review will discuss the imaging appearance of NF1, NF2, and SWN and highlight the important role that imaging plays in informing management decisions in people with tumors associated with these syndromes. Recent technological advances, including the role of both whole-body and localized imaging strategies, routine anatomic and advanced magnetic resonance (MR) imaging sequences such as diffusion-weighted imaging (DWI) with quantitative apparent diffusion coefficient (ADC) mapping, and metabolic imaging techniques (MR spectroscopy and positron emission testing) are discussed in the context of the diagnosis and management of people with NF1, NF2, and SWN based on the most up-to-date clinical imaging studies.

Distribution of diffuse plexiform neurofibroma on the body surface in patients with neurofibromatosis 1

Neurofibromatosis 1 (NF1) is a genetic disease characterized by cutaneous, neurological and osseous abnormalities. Approximately 20% of patients develop plexiform neurofibroma (PN), resulting in impaired quality of life. To evaluate distribution of diffuse PN on the body surface, a retrospective study was conducted for 354 patients with NF1 from 2007 to 2018 in Japan. We investigated a total of 40 patients with clinically apparent superficial diffuse PN. In the cases evaluated, 57.4% of the diffuse PN were located on the trunk, 19.2% the head and neck, 12.8% the lower limbs and 10.6% the upper limbs. Remarkably, 75.0% of the diffuse PN were located on the dorsal side. The frequency was significantly higher on the trunk than on the head and neck (P = 0.026). Our findings provide useful information for giving attention to the high possibility of diffuse PN on the dorsal side before progression in childhood and for future treatment in NF1.

Pediatric peripheral nerve tumors: clinical and surgical aspects

PURPOSE

Pediatric peripheral nerve tumors (PNTs) are rare. Most are related to neurofibromatosis type 1 (NF1) with the potential for malignancy. An ongoing debate occurs about the best approach to such patients. This study describes a cohort of pediatric patients with PNTs and discusses clinical characteristics and surgical treatment.

METHODS

We retrospectively reviewed the charts of seven pediatric patients with eight PNTs surgically treated from 2007 to 2018. Information concerning patient demographics, clinical presentation, PNTs characteristics, treatment choice, and outcome were recorded.

RESULTS

All children presented with intense pain and a palpable mass. Three of the eight tumors were associated with a neurological deficit. Among the four patients with NF1, two had a neurofibroma and two a malignant peripheral nerve sheath tumor (MPNST). Histologically, three of the lesions were a benign peripheral nerve sheath tumor (BPNST), three a MPNST, and one each a desmoid tumor and Ewing's sarcoma. Two of the eight tumors underwent partial tumor excision and six gross total excisions.

CONCLUSIONS

Intense pain at rest, day, and/or night, preventing normal activities; a palpable, hard, immobile mass; an intense Tinel's sign related to the lump; clinical evidence of NF1; and high-speed growth of a tumor in the trajectory of the nerve or plexus should alert the clinician to the potential for malignancy. Preoperative biopsy is not indicated when clinical and imaging findings suggest a benign tumor. The surgical management of PNTs must be to achieve total resection, including wide margins with malignant tumors, though this is not always possible.

Association of plexiform neurofibroma volume changes and development of clinical morbidities in neurofibromatosis 1

Background

Plexiform neurofibromas (PN) in neurofibromatosis 1 (NF1) can cause substantial morbidities. Clinical trials targeting PN have recently described decreases in PN volumes. However, no previous study has assessed the association between changes in PN volumes and PN-related morbidities. Our objective was to assess if increasing PN volume in NF1 is associated with increasing PN-related morbidity.

Methods

This is a retrospective review of patients enrolled on the NCI NF1 natural history study with ≥7 years of data available. Morbidities including pain, motor dysfunction, vision loss, and PN-related surgery were assessed at time of baseline PN MRI with volumetric analysis and time of MRI with maximum PN volume.

Results

Forty-one patients (median age at baseline 8 y) with 57 PN were included. At baseline, 40 PN had at least 1 PN-associated morbidity. During the observation period, 27 PN required increasing pain medication, and these PN grew faster per year (median difference 8.3%; 95% CI: 2.4, 13.8%) than those PN which did not. PN resulting in motor impairment at baseline (n = 11) had larger volumes compared with those that did not (median difference 461 mL; 95% CI: 66.9, 820).

Conclusions

Many NF1 PN were associated with clinically significant morbidity at baseline, highlighting the need for longitudinal morbidity evaluations starting at an early age to capture changes in PN-associated morbidities. Prospective evaluation of standardized patient reported and functional outcomes in clinical trials are ongoing and may allow further characterization of the association of PN volume increase or decrease and clinical changes.

Speech difficulties and patient health communication mediating effects on worry and health-related quality of life in children, adolescents, and young adults with Neurofibromatosis Type 1

The objective was to investigate the serial mediating effects of speech difficulties, patient health communication, and disease-specific worry in the relationship between neurofibromatosis (NF) symptoms (pain and skin symptoms) and total generic health-related quality of life (HRQOL) in children, adolescents, and young adults with NF Type 1 (NF1) from the patient perspective. The Speech, Communication, Worry, Pain, Skin Itch Bother, and Skin Sensations Scales from the Pediatric Quality of Life Inventory (PedsQL) NF1 Module and the PedsQL 4.0 Generic Core Scales were completed in a multi-site national study by 305 patients ages 5-25 years. A serial multiple mediator model analysis was conducted to test the hypothesized sequential mediating effects of speech difficulties, health communication, and worry as intervening variables in the association between NF1 symptoms and HRQOL. Symptoms predictive effects on total generic HRQOL were serially mediated by speech difficulties, patient health communication, and worry. In predictive analytics models utilizing hierarchical multiple regression analyses with age and gender demographic covariates, the pain, skin itch bother, and skin sensations multiple mediator models accounted for 61%, 59%, and 56% of the variance in generic HRQOL (p < .001), reflecting large effect sizes. Speech difficulties, patient health communication, and disease-specific worry explain in part the mechanism of symptoms predictive effects on total generic HRQOL in pediatric patients with NF1. Identifying NF1-specific predictors and serial mediators of total generic HRQOL in pediatric patients with NF1 from the patient perspective enables a patient-centered comprehensive care approach for children, adolescents, and young adults with NF1.

Patient Reported Outcomes Measurement Information System and Quality of Life in Neurological Disorders Measurement System to Evaluate Quality of Life for Children and Adolescents with Neurofibromatosis Type 1 Associated Plexiform Neurofibroma

OBJECTIVE

To assess the health-related quality of life of children with neurofibromatosis type 1-related plexiform neurofibromas (pNF) using a battery of patient-reported outcome measures selected based on a conceptual framework derived from input by patients, parents, and clinicians regarding the most important pNF symptoms and concerns.

STUDY DESIGN

There were 140 children with pNF ages 8-17 years who completed the Patient-Reported Outcomes Measurement Information System (including domains anxiety, depressive symptom, psychosocial stress experiences, fatigue, pain interference, meaning and purpose, positive affect, peer relationships, physical function-mobility) and Quality of Life in Neurological Disorders measurement system (stigma) via an online platform. T-scores for each measure were compared with US population norms.

RESULTS

Children with pNF reported significantly worse scores than the population norms on 8 of 10 domains. Children with at least 1 family member having a diagnosis of neurofibromatosis type 1 and those having pain reported significantly worse symptoms and functioning on all domains. Boys reported significantly worse pain interference, stigma, meaning and purpose, mobility function, and upper extremity function than girls.

CONCLUSIONS

Children with pNF experience significantly worse health-related quality of life on all but 1 domain, highlighting the importance of monitoring children's quality of life over time in clinical research and practice. Future research should evaluate the replicability of these findings and evaluate the validity of the Patient-Reported Outcomes Measurement Information System and Quality of Life in Neurological Disorders measurement system in relation to clinical characteristics among children with pNF.

A combination of skeletal deformations of the dorsal mandible and temporomandibular region detected in orthopantomograms of patients with neurofibromatosis type 1 indicates an associated ipsilateral plexiform neurofibroma

PURPOSE

Neurofibromatosis type 1 (NF1) is a tumour suppressor syndrome and also a bone disease. In the craniofacial region, local skeletal deformities have been recorded in patients with NF1. Obvious syndrome-related alterations of the jaws are particularly conspicuous in the mandible. Here we aimed to analyse the mandibular alterations of NF1-affected individuals from orthopantomograms (OPGs).

MATERIALS AND METHODS

This study analyses 358 OPGs of 358 patients (mean age, 34.63 years; range, 12.57-69.13 years). The OPGs of 179 patients of Caucasian origin with NF1 were investigated (mean age, 34.84 years; range, 12.83-68.89 years; 44.13% male, 55.86% female). The radiographic findings were compared to those obtained from OPGs of sex- and age-matched controls.

RESULTS

Characteristic deformations of the bone regions of interest occur in NF1 patients, especially in patients with plexiform neurofibroma of trigeminal nerve. These findings are always one-sided. The co-occurrence of several skeletal deformations can be expected with very high probability in this patient group.

CONCLUSION

The radiological sign of the unilateral deformed mandible should be included in the diagnostic criteria for NF1. In addition to the diagnostic value in this syndrome, these findings are important for avoiding surgical complications in planned interventions in this region.

Large penile plexiform neurofibroma in an 11-year old boy

Background

Neurofibromatosis is a genetically inherited disorder of the nervous system (brain and spinal cord) which mainly affects the development of nerve (neural) cell tissues, causing tumors (neurofibromas) to develop on nerves. It is the most common single gene disorder of the nervous system and inheritance is through autosomal dominance. They are usually classified into types 1 and 2, the type 1 is the commoner type and also known as superficial neurofibroma. Plexiform neurofibromas are the next most common type of tumor in individuals with type 1 neurofibroma. Plexiform neurofibromas are histologically benign tumors that are made up of a variety of cell types including neuronal axons, Schwann cells, fibroblasts, mast cells, macrophages, perineural cells and extracellular matrix materials such as collagen. They can occur in any part of the body and can grow throughout the person's lifetime, often becoming disfiguring, disabling or deadly via compression of vital structures or conversion to a malignant sarcoma or malignant peripheral nerve sheath turmor. The aim of this report is to present a large penile plexiform neurofibroma which required extensive dissection for complete excision and reconstruction of the phallus and glans penis.

Objectives

To present a huge penile plexiform neurofibroma and the mode of surgical treatment.

Methods

The huge penile plexiform neurofibroma was completely excised and the penile defect resulting from the excision was repaired.

Conclusion

Plexiform neurofibromas are congenital tumors of peripheral nerve sheaths which may also develop near nerve roots deep within the body. They are usually benign but carry a malignant potential in 5-10% of patients. Plexiform neurofibromas are commoner in the face, chest and limbs but the index case occurred on the penile shaft.

Monitoring of plexiform neurofibroma in children and adolescents with neurofibromatosis type 1 by [18 F]FDG-PET imaging. Is it of value in asymptomatic patients?

PURPOSE

About 10% of patients with neurofibromatosis type 1 (NF-1) develop malignant peripheral nerve sheath tumours (MPNST) mostly arising in plexiform neurofibroma (PN); 15% of MPNST arise in children and adolescents. 2-[¹⁸ F]fluoro-2-deoxy-d-glucose ([¹⁸ F]FDG)-PET (where PET is positron emission tomography) is a sensitive method in differentiating PN and MPNST in symptomatic patients with NF-1. This study assesses the value of [¹⁸ F]FDG-PET imaging in detecting malignant transformation in symptomatic and asymptomatic children with PN.

METHODS

Forty-one patients with NF-1 and extensive PN underwent prospective [¹⁸ F]FDG imaging from 2003 to 2014. Thirty-two of the patients were asymptomatic. PET data, together with histological results and clinical course were re-evaluated retrospectively. Maximum standardised uptake values (SUVmax) and lesion-to-liver ratio were assessed.

RESULTS

A total of 104 examinations were performed. Mean age at first PET was 13.5 years (2.6-22.6). Eight patients had at least one malignant lesion; four of these patients were asymptomatic. Two of four symptomatic patients died, while all patients with asymptomatic malignant lesions are alive. All malignant tumours could be identified by PET imaging in both symptomatic and asymptomatic patients. All lesions judged as benign by [¹⁸ F]FDG imaging and clinical judgment were either histologically benign if removed or remained clinically silent during follow-up. SUVmax of malignant and benign lesions overlapped, but no malignant lesion showed FDG uptake ≤3.15. Asymptomatic malignant lesions were detected with a sensitivity of 100%, a negative predictive value of 100% and a specificity of 45.1%.

CONCLUSION

Malignant transformation of PN also occurs in asymptomatic children and adolescents. Detection of MPNST at early stages could increase the possibility of oncologically curative resections.

Biology and Management of Undifferentiated Pleomorphic Sarcoma, Myxofibrosarcoma, and Malignant Peripheral Nerve Sheath Tumors: State of the Art and Perspectives

Undifferentiated pleomorphic sarcomas, myxofibrosarcomas, and malignant peripheral nerve sheath tumors are characterized by complex genomic characteristics and aggressive clinical behavior. Recent advances in the understanding of the pathogenesis of these tumors may allow for the development of more-effective innovative therapeutic strategies, including immunotherapies. This review describes the current knowledge of the epidemiology, clinical presentation, treatment, and pathogenesis of these tumors and highlights ongoing and future research.

Current whole-body MRI applications in the neurofibromatoses: NF1, NF2, and schwannomatosis

OBJECTIVES

The Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) International Collaboration Whole-Body MRI (WB-MRI) Working Group reviewed the existing literature on WB-MRI, an emerging technology for assessing disease in patients with neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN), to recommend optimal image acquisition and analysis methods to enable WB-MRI as an endpoint in NF clinical trials.

METHODS

A systematic process was used to review all published data about WB-MRI in NF syndromes to assess diagnostic accuracy, feasibility and reproducibility, and data about specific techniques for assessment of tumor burden, characterization of neoplasms, and response to therapy.

RESULTS

WB-MRI at 1.5T or 3.0T is feasible for image acquisition. Short tau inversion recovery (STIR) sequence is used in all investigations to date, suggesting consensus about the utility of this sequence for detection of WB tumor burden in people with NF. There are insufficient data to support a consensus statement about the optimal imaging planes (axial vs coronal) or 2D vs 3D approaches. Functional imaging, although used in some NF studies, has not been systematically applied or evaluated. There are no comparative studies between regional vs WB-MRI or evaluations of WB-MRI reproducibility.

CONCLUSIONS

WB-MRI is feasible for identifying tumors using both 1.5T and 3.0T systems. The STIR sequence is a core sequence. Additional investigation is needed to define the optimal approach for volumetric analysis, the reproducibility of WB-MRI in NF, and the diagnostic performance of WB-MRI vs regional MRI.

Sleep and pulmonary outcomes for clinical trials of airway plexiform neurofibromas in NF1

OBJECTIVE

Plexiform neurofibromas (PNs) are complex, benign nerve sheath tumors that occur in approximately 25%-50% of individuals with neurofibromatosis type 1 (NF1). PNs that cause airway compromise or pulmonary dysfunction are uncommon but clinically important. Because improvement in sleep quality or airway function represents direct clinical benefit, measures of sleep and pulmonary function may be more meaningful than tumor size as endpoints in therapeutic clinical trials targeting airway PN.

METHODS

The Response Evaluation in Neurofibromatosis and Schwannomatosis functional outcomes group reviewed currently available endpoints for sleep and pulmonary outcomes and developed consensus recommendations for response evaluation in NF clinical trials.

RESULTS

For patients with airway PNs, polysomnography, impulse oscillometry, and spirometry should be performed to identify abnormal function that will be targeted by the agent under clinical investigation. The functional group endorsed the use of the apnea hypopnea index (AHI) as the primary sleep endpoint, and pulmonary resistance at 10 Hz (R10) or forced expiratory volume in 1 or 0.75 seconds (FEV1 or FEV0.75) as primary pulmonary endpoints. The group defined minimum changes in AHI, R10, and FEV1 or FEV0.75 for response criteria. Secondary sleep outcomes include desaturation and hypercapnia during sleep and arousal index. Secondary pulmonary outcomes include pulmonary resistance and reactance measurements at 5, 10, and 20 Hz; forced vital capacity; peak expiratory flow; and forced expiratory flows.

CONCLUSIONS

These recommended sleep and pulmonary evaluations are intended to provide researchers with a standardized set of clinically meaningful endpoints for response evaluation in trials of NF1-related airway PNs.

Patient-reported outcomes of pain and physical functioning in neurofibromatosis clinical trials

OBJECTIVE

Tumors and other disease complications of neurofibromatosis (NF) can cause pain and negatively affect physical functioning. To document the clinical benefit of treatment in NF trials targeting these manifestations, patient-reported outcomes (PROs) assessing pain and physical functioning should be included as study endpoints. Currently, there is no consensus on the selection and use of such measures in the NF population. This article presents the recommendations of the PRO group of the Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) International Collaboration for assessing the domains of pain and physical functioning for NF clinical trials.

METHODS

The REiNS PRO group reviewed and rated existing PRO measures assessing pain intensity, pain interference, and physical functioning using their systematic method. Final recommendations are based primarily on 4 main criteria: patient characteristics, item content, psychometric properties, and feasibility for clinical trials.

RESULTS

The REiNS PRO group chose the Numeric Rating Scale-11 (≥8 years) to assess pain intensity, the Pain Interference Index (6-24 years) and the Patient-Reported Outcome Measurement Information System (PROMIS) Pain Interference Scale (≥18 years) to evaluate pain interference, and the PROMIS Physical Functioning Scale to measure upper extremity function and mobility (≥5 years) for NF clinical trials.

CONCLUSIONS

The REiNS Collaboration currently recommends these PRO measures to assess the domains of pain and physical functioning for NF clinical trials; however, further research is needed to evaluate their use in individuals with NF. A final consensus recommendation for the pain interference measure will be disseminated in a future publication based on findings from additional published research.

Activity of Selumetinib in Neurofibromatosis Type 1-Related Plexiform Neurofibromas

BACKGROUND

Effective medical therapies are lacking for the treatment of neurofibromatosis type 1-related plexiform neurofibromas, which are characterized by elevated RAS-mitogen-activated protein kinase (MAPK) signaling.

METHODS

We conducted a phase 1 trial of selumetinib (AZD6244 or ARRY-142886), an oral selective inhibitor of MAPK kinase (MEK) 1 and 2, in children who had neurofibromatosis type 1 and inoperable plexiform neurofibromas to determine the maximum tolerated dose and to evaluate plasma pharmacokinetics. Selumetinib was administered twice daily at a dose of 20 to 30 mg per square meter of body-surface area on a continuous dosing schedule (in 28-day cycles). We also tested selumetinib using a mouse model of neurofibromatosis type 1-related neurofibroma. Response to treatment (i.e., an increase or decrease from baseline in the volume of plexiform neurofibromas) was monitored by using volumetric magnetic resonance imaging analysis to measure the change in size of the plexiform neurofibroma.

RESULTS

A total of 24 children (median age, 10.9 years; range, 3.0 to 18.5) with a median tumor volume of 1205 ml (range, 29 to 8744) received selumetinib. Patients were able to receive selumetinib on a long-term basis; the median number of cycles was 30 (range, 6 to 56). The maximum tolerated dose was 25 mg per square meter (approximately 60% of the recommended adult dose). The most common toxic effects associated with selumetinib included acneiform rash, gastrointestinal effects, and asymptomatic creatine kinase elevation. The results of pharmacokinetic evaluations of selumetinib among the children in this trial were similar to those published for adults. Treatment with selumetinib resulted in confirmed partial responses (tumor volume decreases from baseline of ≥20%) in 17 of the 24 children (71%) and decreases from baseline in neurofibroma volume in 12 of 18 mice (67%). Disease progression (tumor volume increase from baseline of ≥20%) has not been observed to date. Anecdotal evidence of decreases in tumor-related pain, disfigurement, and functional impairment was observed.

CONCLUSIONS

Our early-phase data suggested that children with neurofibromatosis type 1 and inoperable plexiform neurofibromas benefited from long-term dose-adjusted treatment with selumetinib without having excess toxic effects. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01362803 .).

Bevacizumab for Treatment-Refractory Pain Control in Neurofibromatosis Patients

OBJECTIVE

Chronic pain is a well-known morbidity associated with neurofibromatosis (NF) for which better therapies are needed. Surgery, radiation, and pain medications have been utilized, but often fail to relieve debilitating pain. One patient at our institution was noted to have near complete resolution of pain after treatment with bevacizumab for progressive neurologic deficit associated with NF2, suggesting its potential as an effective pain control method. We aim to better characterize the use of bevacizumab for pain control in this subset of patients.  Patients and Methods: We retrospectively reviewed 38 NF patients treated at our institution.   Results: Of the 38 total NF patients, we found that 63% reported chronic pain, with 18% reporting chronic opiate usage. Nine patients with chronic pain were considered for bevacizumab treatment and five went on to receive infusions. Of these patients, four out of five had previous surgical debulking and two out of five had previous radiation for attempted pain control. One patient had a lesion not amenable to surgery or radiation. Patients received a median of 13 cycles of bevacizumab, and four out of five patients reported a decrease in subjective pain. All patients that had pain relief had a relapse of pain symptoms when the dose was reduced or infusions were paused. Seventy-five percent were able to decrease opiate use. No major complications were noted. All five patients have elected to continue infusions for pain control.  Conclusion: Bevacizumab was, in general, well tolerated and should be considered as a treatment option in NF patients with chronic pain refractory or not amenable to surgical decompression and debulking, radiation, and pain medication.

Multifactorial pathological hip subluxation in neurofibromatosis type-1 (NF1) due to intra-articular plexiform neurofibroma, lumbar radiculopathy and neurofibromatous polyneuropathy

Neurofibromatosis type-1 (NF1) is a multisystem disorder with very rare descriptions of hip instability. We report a case of a 37-year-old man with known NF1 and childhood-onset of left foot drop, who developed persistent left hip pain following a minor trauma. Physical examination revealed left-sided mild foot drop, hip abductor weakness, bilateral sensory loss in feet and an antalgic gait. Work-up revealed anterolateral subluxation of the left femoral head along with left hip plexiform neurofibroma (PN), dysplastic and degenerative changes, neurofibromatous neuropathy and chronic left L5 radiculopathy. Initial improvement after surgical resection of the PN was unsustained and followed by increasing pain and recurrent hip subluxation, prompting a total hip arthroplasty which resulted in marked improvement of symptoms. Our patient, unlike those in other reports, illustrates multiple aetiologies of hip dislocation in NF1 including local factors, lumbar radiculopathy and polyneuropathy, reinforcing the importance of a multidisciplinary approach in the management of such cases.

Distinctive Cancer Associations in Patients With Neurofibromatosis Type 1

PURPOSE

The current study was designed to determine the risk of cancer in patients with neurofibromatosis type 1 (NF1) by cancer type, age, and sex with unprecedented accuracy to be achieved by combining two total population-based registers.

PATIENTS AND METHODS

A population-based series of patients with NF1 (N = 1,404; 19,076 person-years) was linked to incident cancers recorded in the Finnish Cancer Registry and deaths recorded in the national Population Register Centre between 1987 and 2012. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were calculated for selected cancer types. Survival of the patients with cancer with and without NF1 was compared.

RESULTS

In malignant peripheral nerve sheath tumors and CNS tumors, the cancers traditionally associated with NF1, we observed SIRs of 2,056 (95% CI, 1,561 to 2,658), and 37.5 (95% CI, 30.2 to 46.0), respectively, and SMRs of 2,301 (95% CI, 1,652 to 3,122) and 30.2 (95% CI, 19.1 to 45.2), respectively. We found an unequivocally increased risk for breast cancer. In particular, SIR was 11.1 (95% CI, 5.56 to 19.5) for breast cancer in women with NF1 age < 40 years; the overall SMR for breast cancer was 5.20 (95% CI, 2.38 to 9.88). Particularly high overall SIRs were observed in patients with NF1 age < 15 years: women, 87.6 (95% CI, 58.6 to 125); men, 45.6 (95% CI, 28.4 to 68.5). An estimated lifetime cancer risk for patients with NF1 was 59.6%. The 5-year survival of patients with cancer and NF1, excluding nervous tissue cancers, was worse than that of comparable patients with cancers without NF1 (54.0% v 67.5%; P = .01).

CONCLUSION

Our results emphasize the general cancer proclivity of patients with NF1. These findings should translate to clinical practices to determine clinical interventions and focused follow-up of patients with NF1.

Neurofibromatosis 1-associated panhypopituitarism presenting as hypoglycaemic seizures and stroke-like symptoms

A 37-year-old man with a known history of neurofibromatosis 1 (NF1) presented within 2 days of diarrhoeal illness followed by encephalopathy, facial twitching, hypoglycaemia, hypotension, tachycardia and low-grade fever. Examination showed multiple café-au-lait spots and neurofibromas over the trunk, arms and legs and receptive aphasia with right homonymous hemianopia, which resolved. Workup for cardiac, inflammatory and infectious aetiologies was unrevealing. A brain MRI showed gyral swelling with increased T2 fluid-attenuated inversion recovery signal and diffusion restriction in the left cerebral cortex. Neuroendocrine findings suggested panhypopituitarism with centrally derived adrenal insufficiency. Supportive treatment, hormone supplementation, antibiotics, antivirals and levetiracetam yielded clinical improvement. A follow-up brain MRI showed focal left parieto-occipital atrophy with findings of cortical laminar necrosis. In conclusion, we describe a case of NF1-associated panhypopituitarism presenting as hypoglycaemic seizures and stroke-like findings, hitherto unreported manifestations of NF1. Prompt recognition and treatment of these associated conditions can prevent devastating complications.

Pain interference in youth with neurofibromatosis type 1 and plexiform neurofibromas and relation to disease severity, social-emotional functioning, and quality of life

The physical manifestations of neurofibromatosis type 1 (NF1) can cause chronic pain. This study investigated the impact of pain in youth with NF1 and plexiform neurofibromas (PNs) and its relationship to disease factors, social-emotional functioning, and quality of life (QOL) within a biopsychosocial framework. Caregivers of 59 children and adolescents with NF1 and PNs (6-18 years), and 41 of these youth (10-18 years), completed questionnaires assessing social-emotional functioning and QOL, including an item on pain interference. Measures of disease severity included total PN volume by percent body weight and number of disease complications. Both caregiver (73%) and self-report (59%) ratings indicated that pain interferes with the child's daily functioning despite 33% taking pain medication. Based on caregivers' behavior ratings, more symptoms of anxiety and larger tumor volumes predicted greater pain interference, while greater pain interference, worse depressive symptoms, and more disease complications predicted poorer QOL. As rated by adolescents, more symptoms of anxiety predicted greater pain interference, while greater pain interference and social stress predicted poorer QOL. Further, social-emotional problems mediate the relationship between pain interference and QOL. Thus, pain interferes with daily functioning in the majority of youth with NF1 and PNs even when using pain medication. The impact of pain interference, disease severity, and particularly social-emotional problems on QOL highlights the interaction between physical and psychological states in NF1. Future research and treatment of pain in this population should utilize a biopsychosocial approach and involve multidisciplinary therapies including psychological interventions that target social-emotional functioning.

A RASopathy gene commonly mutated in cancer: the neurofibromatosis type 1 tumour suppressor

Neurofibromatosis type 1 (NF1) is a common genetic disorder that predisposes affected individuals to tumours. The NF1 gene encodes a RAS GTPase-activating protein called neurofibromin and is one of several genes that (when mutant) affect RAS-MAPK signalling, causing related diseases collectively known as RASopathies. Several RASopathies, beyond NF1, are cancer predisposition syndromes. Somatic NF1 mutations also occur in 5-10% of human sporadic cancers and may contribute to resistance to therapy. To highlight areas for investigation in RASopathies and sporadic tumours with NF1 mutations, we summarize current knowledge of NF1 disease, the NF1 gene and neurofibromin, neurofibromin signalling pathways and recent developments in NF1 therapeutics.

Tumor burden evaluation in NF1 patients with plexiform neurofibromas in daily clinical practice

BACKGROUND

Existing volumetric measurements of plexiform neurofibromas (PNs) are time consuming and error prone, as they require delineation of PN boundaries, a procedure that is not practical in the typical clinical setting. The aim of this study is to assess the Plexiform Neurofibroma Instant Segmentation Tool (PNist), a novel semi-automated segmentation program that we developed for PN delineation in a clinical context. PNist was designed to greatly simplify volumetric assessment of PNs through use of an intuitive user interface while providing objectively consistent results with minimal interobserver and intraobserver variabilities in reasonable time.

MATERIALS AND METHODS

PNs were measured in 30 magnetic resonance imaging (MRI) scans from 12 patients with neurofibromatosis 1. Volumetric measurements were performed using PNist and compared to a standard semi-automated volumetric method (Analyze 9.0).

RESULTS

High correlation was detected between PNist and the semi-automated method (R(2) = 0.996), with a mean volume overlap error of 9.54 % and low intraobserver and interobserver variabilities. The segmentation time required for PNist was 60 % of the time required for Analyze 9.0 (360 versus 900 s, respectively). PNist was also reliable when assessing changes in tumor size over time, compared to the existing commercial method.

CONCLUSIONS

Our study suggests that the new PNist method is accurate, intuitive, and less time consuming for PN segmentation compared to existing commercial volumetric methods. The workflow is simple and user-friendly, making it an important clinical tool to be used by radiologists, neurologists and neurosurgeons on a daily basis, helping them deal with the complex task of evaluating PN burden and progression.

Quantitative associations of scalp and body subcutaneous neurofibromas with internal plexiform tumors in neurofibromatosis 1

Internal plexiform neurofibromas are a major cause of adverse outcomes in patients with neurofibromatosis 1 (NF1). We investigated the relationship of the numbers of subcutaneous neurofibromas of the scalp or body to internal plexiform tumor volume in 120 NF1 patients who had undergone whole body magnetic resonance imaging (MRI). We identified internal plexiform neurofibromas in 55% of patients, subcutaneous neurofibromas of the body in 75%, and subcutaneous neurofibromas of the scalp in 45%. The number of subcutaneous neurofibromas of the body and scalp were associated with each other (Spearman's Rho = 0.36; P < 0.001). The presence of internal tumors was associated with the presence (odds ratio [OR] = 4.38, 95% confidence interval [CI] 2.04-9.86, P < 0.001) and number (OR = 1.06 per neurofibroma, 95% CI 1.02-1.13, P < 0.001) of subcutaneous neurofibromas of the scalp. The total internal tumor volume was associated with the number of subcutaneous neurofibromas of the body (OR = 1.00086 per neurofibroma, 1.000089-1.0016, P = 0.029) and of the scalp (OR = 1.056 per neurofibroma, 1.029-1.083, P < 0.0001). Numbers of subcutaneous neurofibromas of the scalp and body are associated with internal plexiform tumor burden in NF1. Recognition of these associations may improve clinical management by helping to identify patients who will benefit most from whole body MRI and more intense clinical surveillance.

Preclinical assessment of the anticancer drug response of plexiform neurofibroma tissue using primary cultures

BACKGROUND AND PURPOSE

Individualized drug testing for tumors using a strategy analogous to antibiotic tests for infectious diseases would be highly desirable for personalized and individualized cancer care.

METHODS

Primary cultures containing tumor and nontumor stromal cells were utilized in a novel strategy to test drug responses with respect to both efficacy and specificity. The strategy tested in this pilot study was implemented using four primary cultures derived from plexiform neurofibromas. Responses to two cytotoxic drugs (nilotinib and imatinib) were measured by following dose-dependent changes in the proportions of tumor and nontumor cells, determined by staining them with cell-type-specific antibodies. The viability of the cultured cells and the cytotoxic effect of the drugs were also measured using proliferation and cytotoxicity assays.

RESULTS

The total number of cells decreased after the drug treatment, in accordance with the observed reduction in proliferation and increased cytotoxic effect upon incubation with the two anticancer drugs. The proportions of Schwann cells and fibroblasts changed dose-dependently, although the patterns of change varied between the tumor samples (from different sources) and between the two drugs. The highly variable in vitro drug responses probably reflect the large variations in the responses of tumors to therapies between individual patients in vivo.

CONCLUSIONS

These preliminary results suggest that the concept of assessing in vitro drug responses using primary cultures is feasible, but demands the extensive further development of an application for preclinical drug selection and drug discovery.

Neurofibromatosis type 1: a multidisciplinary approach to care

Neurofibromatosis type 1 is a relatively common inherited disorder. Patients have a high predisposition to develop both benign and malignant tumours. Although many manifestations of neurofibromatosis type 1 affect the nervous system, other organs and tissues can also be affected. Because of the varying features and clinical heterogeneity inherent to this disorder, patients can present to different medical and surgical specialists and, therefore, the association of clinical symptoms with neurofibromatosis type 1 might not be appreciated. Thus, for prompt diagnosis and to provide optimum care for patients with neurofibromatosis type 1, clinicians must be aware of the diverse clinical features of this disorder. We advocate a multidisciplinary approach to care, entailing a dedicated team of specialists throughout the lifetime of the patient. As our understanding of this disorder deepens through basic laboratory and clinical investigations, swift implementation of new effective treatments becomes feasible.

Phase II trial of pirfenidone in children and young adults with neurofibromatosis type 1 and progressive plexiform neurofibromas

BACKGROUND

Pirfenidone, an oral anti-inflammatory, antifibrotic agent with activity in idiopathic pulmonary fibrosis, may mediate anti-tumor activity in neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PN) by inhibition of fibroblast proliferation and collagen synthesis. The primary objective of this open label, single arm phase II trial was to evaluate the activity of pirfenidone in children and young adults with inoperable PN.

PROCEDURE

Patients (3-21 years) with NF1-related progressive PN received pirfenidone at the previously determined optimal dose (500 mg/m(2) orally, q8h) on a continuous dosing schedule (one cycle = 28 days). Volumetric MRI analysis was used to assess response. Progression was defined as ≥ 20% PN volume increase compared to baseline. Pirfenidone would be considered active if it doubled the median time to progression (TTP) compared to the TTP on the placebo arm of a phase II trial with the farnesyltransferase inhibitor tipifarnib, which used near identical eligibility criteria. Toxicities, objective response rate, and quality of life (QOL) also were evaluated.

RESULTS

Thirty-six patients were enrolled and tolerated pirfenidone well with intermittent nausea and vomiting as the most frequent toxicities. A dose reduction was required in only three patients. The median TTP for pirfenidone was 13.2 months compared to 10.6 months for the placebo control group from the tipifarnib trial (two-tailed P = 0.92; one-tailed P = 0.46). No objective responses were observed.

CONCLUSIONS

Pirfenidone was well tolerated, but did not demonstrate activity as defined in this trial and does not warrant further evaluation in children with NF1 and progressive PN.

Conclusions and future directions for the REiNS International Collaboration

The Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) International Collaboration was established with the goal to develop consensus recommendations for the use of endpoints in neurofibromatosis (NF) clinical trials. This supplement includes the first series of REiNS recommendations for the use of patient-reported, functional, and visual outcomes, and for the evaluation of imaging response in NF clinical trials. Recommendations for neurocognitive outcome measures, the use of whole-body MRI in NF, the evaluation of potential biomarkers of disease, and the comprehensive evaluation of functional and patient-reported outcomes in NF are in development. The REiNS recommendations are made based on current knowledge. Experience with the use of the recommended endpoints in clinical trials, development of new tools and technologies, new knowledge of the natural history of NF, and advances in the methods used to analyze endpoints will likely lead to modifications of the currently proposed guidelines, which will be shared with the NF research community through the REiNS Web site www.reinscollaboration.org. Due to the clinical complexity of NF, there is a need to seek expertise from multiple medical disciplines, regulatory agencies, and industry to develop trial endpoints and designs, which will lead to the identification and approval of effective treatments for NF tumor and nontumor manifestations. The REiNS Collaboration welcomes anyone interested in providing his or her expertise toward this effort.

PNist: interactive volumetric measurements of plexiform neurofibromas in MRI scans

PURPOSE

Volumetric measurements of plexiform neurofibromas (PNs) are time consuming and error prone, as they require the delineation of the PN boundaries, which is mostly impractical in the daily clinical setup. Accurate volumetric measurements are seldom performed for these tumors mainly due to their great dispersion, size and multiple locations. This paper presents a semiautomatic method for segmentation of PN from STIR MRI scans.

METHODS

Plexiform neurofibroma interactive segmentation tool (PNist) is a new tool to segment PNs in STIR MRI scans. The method is based on histogram tumor models computed from a training set.

RESULTS

Experimental results from 28 datasets show an average absolute volume difference of 6.8 % with an average user time of approximately 7 min versus more than 13 min with manual delineation. In complex cases, the PNist user time is less than half in compared to state-of-the-art tools.

CONCLUSIONS

PNist is a new method for the semiautomatic segmentation of PN lesions. Its simplicity and reliability make it unique among other state-of-the-art methods. It has the potential to become a clinical tool that allows the reliable evaluation of PN burden and progression.

Ophthalmological assessment of children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder, caused by mutations in the NF1 gene, located on chromosome band 17q11.2. In 1988, the National Institutes of Health created specific criteria for the diagnosis of NF1. Four cardinal criteria are assessed through ophthalmological screening: Lisch nodules, optic pathway glioma, a distinctive osseous lesion (sphenoid dysplasia), and the (orbital) plexiform neurofibroma. NF1 patients are prone to the development of central and peripheral nervous system tumors. Especially young children are at risk for growing optic pathway gliomas that can threaten their sight. From an early age, children with NF1 undergo regular ophthalmological examinations. Little is known about the natural progress of these clinical features and the guidelines for screening and follow-up are controversial. Several questions remain unanswered.

CONCLUSION

Most of these questions could be solved by better understanding of the natural history of optic pathway gliomas. There is a tendency towards using vision as a primary objective in clinical treatment trials; this way we can evaluate new treatment strategies and focus specifically on visual evolution so we will be able to select even more carefully which patient would benefit treatment. For future clinical trials, a standardized visual acuity assessment protocol is therefore mandatory.

Nevus anemicus in neurofibromatosis type 1: a potential new diagnostic criterion

BACKGROUND

Children with multiple café-au-lait macules (CALMs) may be followed for years before a second National Institutes of Health clinical criterion of neurofibromatosis type 1 (NF1) develops to confirm the diagnosis.

OBJECTIVE

We sought to assess the prevalence of nevus anemicus (NA) in NF1 and its association with neuro-ophthalmologic complications.

METHODS

This was a prospective multicenter case-control study of 210 consecutive patients with multiple CALMs. Patients with NF1 were matched for age, sex, and center with control subjects. We documented the number, location, and morphologic appearance of NA; dermatologic features of NF1; magnetic resonance imaging results; and family history.

RESULTS

In all, 77 (51%) patients with NF1 had NA compared with 6 (2%) control subjects. NA was not detected in 26 patients with other genodermatoses associated with CALMs. Patients with NF1 and NA were younger than those without NA (median age: 17 years) (P = .002). NA was mostly localized to the upper anterior aspect of the chest. NA was not significantly linked with other clinical manifestations of NF1, including optic glioma and unidentified bright objects.

LIMITATIONS

A potential referral bias associated with tertiary care centers is a limitation.

CONCLUSIONS

NA appears to have a high prevalence and specificity in NF1 and might serve as a marker for NF1 in children with multiple CALMs.

Visual outcomes in children with neurofibromatosis type 1 and orbitotemporal plexiform neurofibromas

PURPOSE

To describe the visual outcomes and volumetric magnetic resonance imaging (3D MRI) in children with neurofibromatosis type 1 (NF1) and orbitotemporal plexiform neurofibromas.

DESIGN

Multicenter retrospective case series.

METHODS

Two institutions with dedicated NF1 clinical research programs queried their established clinical databases for children with orbitotemporal plexiform neurofibromas. Visual acuity, refractive error, ambylopia, and treatment history were abstracted. Extent of orbitotemporal plexiform neurofibroma involvement was assessed clinically and with 3D MRI analysis. Children with optic pathway gliomas or ocular causes of decreased visual acuity (ie, cataracts, glaucoma) other than strabismus or anisometropia were excluded.

RESULTS

Twenty-one children met inclusion criteria (median age 8 years, range 0.33-23 years). Orbitotemporal plexiform neurofibroma location was classified as isolated eyelid (n = 6), eyelid and orbit (n = 7), orbit and temporal region (n = 7), or diffuse orbit (n = 1). Three subjects had bilateral orbital involvement. Amblyopia secondary to the orbitotemporal plexiform neurofibroma was present in 13 subjects (62%) and was caused by strabismus (n = 2, 10%), occlusion from ptosis (n = 9, 43%), or anisometropia (n = 9, 43%), or a combination of factors (n = 6, 29%). MRI-derived volumes were measured in 19 subjects (median 41.8 mL, range 2.7-754 mL). All subjects with amblyopia had orbitotemporal plexiform neurofibroma volumes greater than 10 mL.

CONCLUSION

In our series, amblyopia occurs in more than half of NF1 children with orbitotemporal plexiform neurofibromas, most commonly because of ptosis and anisometropia. The 3D MRI analysis allowed for sensitive measurement of orbitotemporal plexiform neurofibroma size, and larger volumes were associated with development of amblyopia.

Optimizing biologically targeted clinical trials for neurofibromatosis

INTRODUCTION

The neurofibromatoses (neurofibromatosis type 1, NF1 and neurofibromatosis type 2, NF2) comprise the most common inherited conditions in which affected children and adults develop tumors of the central and peripheral nervous system. In this review, the authors discuss how the establishment of the Neurofibromatosis Clinical Trials Consortium (NFCTC) has positively impacted on the design and execution of treatment studies for individuals with NF1 and NF2.

AREAS COVERED

Using an extensive PUBMED search in collaboration with select NFCTC members expert in distinct NF topics, the authors discuss the clinical features of NF1 and NF2, the molecular biology of the NF1 and NF2 genes, the development and application of clinically relevant Nf1 and Nf2 genetically engineered mouse models and the formation of the NFCTC to enable efficient clinical trial design and execution.

EXPERT OPINION

The NFCTC has resulted in a more seamless integration of mouse preclinical and human clinical trials efforts. Leveraging emerging enabling resources, current research is focused on identifying subtypes of tumors in NF1 and NF2 to deliver the most active compounds to the patients most likely to respond to the targeted therapy.

Non-coding RNA ANRIL and the number of plexiform neurofibromas in patients with NF1 microdeletions

Background

Neurofibromatosis type-1 (NF1) is caused by mutations of the NF1 gene at 17q11.2. In 95% of non-founder NF1 patients, NF1 mutations are identifiable by means of a comprehensive mutation analysis. 5-10% of these patients harbour microdeletions encompassing the NF1 gene and its flanking regions. NF1 is characterised by tumours of the peripheral nerve sheaths, the pathognomonic neurofibromas. Considerable inter- and intra-familial variation in expressivity of the disease has been observed which is influenced by genetic modifiers unrelated to the constitutional NF1 mutation. The number of plexiform neurofibromas (PNF) in NF1 patients is a highly heritable genetic trait. Recently, SNP rs2151280 located within the non-coding RNA gene ANRIL at 9p21.3, was identified as being strongly associated with PNF number in a family-based association study. The T-allele of rs2151280, which correlates with reduced ANRIL expression, appears to be associated with higher PNF number. ANRIL directly binds to the SUZ12 protein, an essential component of polycomb repressive complex 2, and is required for SUZ12 occupancy of the CDKN2A/CDKN2B tumour suppressor genes as well as for their epigenetic silencing.

Methods

Here, we explored a potential association of PNF number and PNF volume with SNP rs2151280 in 29 patients with constitutional NF1 microdeletions using the exact Cochran-Armitage test for trends and the exact Mann–Whitney–Wilcoxon test. Both the PNF number and total tumour volume in these 29 NF1 patients were assessed by whole-body MRI. The NF1 microdeletions observed in these 29 patients encompassed the NF1 gene as well as its flanking regions, including the SUZ12 gene.

Results

In the 29 microdeletion patients investigated, neither the PNF number nor PNF volume was found to be associated with the T-allele of rs2151280.

Conclusion

Our findings imply that, at least in patients with NF1 microdeletions, PNF susceptibility is not associated with rs2151280. Although somatic inactivation of the NF1 wild-type allele is considered to be the PNF-initiating event in NF1 patients with intragenic mutations and patients with NF1 microdeletions, both patient groups may differ with regard to tumour progression because of the heterozygous constitutional deletion of SUZ12 present only in patients with NF1 microdeletions.

Growth dynamics of plexiform neurofibromas: a retrospective cohort study of 201 patients with neurofibromatosis 1

Background

To examine the natural growth dynamics of internal plexiform neurofibromas (PNs) in patients with neurofibromatosis 1 (NF1).

Methods

Two hundred and one NF1 patients underwent whole body MRI (WBMRI). Tumour burden was estimated volumetrically. Non-parametric Spearman’s rho correlation coefficients were used to analyse the relationship of growth rate to tumour volume and age. Chi-squared and Mann–Whitney U tests were used for analysing the association of tumour occurrence with sex or age. Chi-squared tests were used to analyse the association of tumour growth with age group.

Results

Seventy-one of 171 patients with serial WBMRI exams had internal PNs (median follow up 2.2 years [1.1 to 4.9 years]). Median whole body tumour volume was 86.4 mL [5.2 to 5878.5 mL]) with a median growth rate of 3.7%/year (−13.4 to 111%/year) that correlated with larger whole body tumour volume (P<0.001) and lower age (P=0.004). No new PNs developed in 273.0 patient-years among patients without tumours. Rate of new tumour development among patients with PNs was 0.6%/year (95% confidence interval 0.02 to 3.4%). Twenty-seven (13.5%) tumours increased significantly and were more frequent among children (P<0.001). Growth rate of tumours was inversely correlated with age (Spearman’s rho=−0.330, P<0.001). Seventy-one (35.5%) tumours had smaller volumes on follow up (median −3.4%/year [−0.07% to −35.9%/year]).

Conclusion

Children with NF1 and internal PNs are at risk for tumour growth. Most PNs grow slowly or not at all, and some decrease in size. New tumours are infrequent in NF1 patients with PNs and unlikely in patients without PNs.

Dissecting the clinical phenotype associated with mosaic type-2 NF1 microdeletions

Patients with large deletions of the NF1 gene and its flanking regions (termed NF1 microdeletions) generally exhibit more severe clinical manifestations of neurofibromatosis type-1 (NF1). Here, we have investigated the clinical phenotype displayed by eight patients harbouring mosaic type-2 NF1 microdeletions. These patients did not exhibit facial dysmorphism, attention deficit hyperactivity disorder, delayed cognitive development and/or learning disabilities, cognitive impairment, congenital heart disease, hyperflexibility of joints, large hands and feet, muscular hypotonia or bone cysts. All these features have previously been reported to be disproportionately associated with germline (i.e. non-mosaic) type-1 NF1 microdeletions as compared with the general NF1 population. Plexiform neurofibromas were also less prevalent in patients with mosaic type-2 NF1 microdeletions as compared with patients carrying constitutional (germline) type-1 NF1 microdeletions. Five of the eight patients with mosaic type-2 deletions investigated here had 20-250 cutaneous neurofibromas, but only one of them exhibited a high load of cutaneous neurofibromas (N > 1,000). By contrast, a previous study indicated a high burden of cutaneous neurofibromas (N > 1,000) in 50% of adult patients with germline type-1 NF1 deletions. Patients with germline type-1 NF1 microdeletions have been reported to have an increased lifetime risk of 16-26% for a malignant peripheral nerve sheath tumour (MPNST). In this study, one of the eight investigated mosaic type-2 microdeletion patients developed an MPNST. We conclude that patients with mosaic type-2 NF1 microdeletions may also be at an increased risk of MPNSTs despite their generally milder disease manifestations as compared with germline type-1 NF1 microdeletions.

Pediatric plexiform neurofibromas: impact on morbidity and mortality in neurofibromatosis type 1

OBJECTIVE

To characterize morbidity, mortality, and surgical outcomes in pediatric patients with symptomatic plexiform neurofibromas (PNFs).

STUDY DESIGN

We conducted retrospective analysis of data from clinical records of surgical history and other neurofibromatosis type 1 (NF1)-related complications in children with PNFs seen at Cincinnati Children's Hospital Medical Center between 1997 and 2007.

RESULTS

A total of 154 children with NF1 and PNFs were identified. Children with symptomatic PNFs had increased incidence of other NF1-related tumors (P < .05). Patients with NF1 and PNFs had a higher mortality rate (5/154, 3.2%) when compared with patients without or with asymptomatic PNFs (2/366, 0.5%; P = .024). The most common morbidities leading to surgeries were neurologic, disfigurement, orthopedic, and airway complaints. Less extensive resection predicted a shorter interval to second surgery (P < .0019). The highest recurrence was seen in tumors located in the head, neck, and thorax (P < .001).

CONCLUSIONS

These findings quantify the increased risk for additional tumors and mortality associated with symptomatic PNFs. Surgical interventions were required in many cases and resulted in added morbidity in some cases. Patients with PNFs were more likely to benefit from surgery when the indications were airway compression or disfigurement.

Internal tumor burden in neurofibromatosis Type I patients with large NF1 deletions

Neurofibromatosis Type 1 (NF1) is a frequent tumor suppressor gene disorder characterized by multiple benign tumors and high risk of malignancy. Internal tumor burden is a major disease-associated manifestation and can be most adequately assessed by magnetic resonance imaging of the whole body. Approximately 5% of NF1 patients have constitutional large NF1-deletions that are generally associated with more severe clinical manifestations. Here, we investigated whether these deletion patients also have more and/or larger internal tumors by assessing internal tumors and their total volume (exclusive of cutaneous and subcutaneous) in 38 NF1 deletion patients (including eight mosaic cases) and 114 age- and gender-matched NF1 patients without deletions. The incidence of internal tumors was significantly lower in mosaic deletion patients (1/8 = 13%) but did not differ between the 30 nonmosaic deletion patients and the 90 age- and gender-matched NF1 patients without large deletions used as controls. Neither the number nor the total volume of tumors per patient differed significantly between the latter two groups. However, extremely high tumor burden (>3,000 ml) was significantly more frequent among nonmosaic NF1 deletion patients than among NF1 patients without large deletions (13% vs. 1%, P = 0.014). Thus, as a group, patients with NF1 deletions do not exhibit a significantly higher internal tumor burden than NF1 patients without such deletions. However, deletion patients can frequently have extremely large internal tumors and thus demand special attention.

Therapeutics for childhood neurofibromatosis type 1 and type 2

OPINION STATEMENT

Neurofibromatosis type 1 (NF1) and type 2 (NF2) are genetically and medically distinct neurocutaneous disorders that are both associated with tumors affecting the central and peripheral nervous systems. NF1 has a frequency of 1 in 3,000, compared with 1 in 30,000 for NF2. Careful surveillance is important for both conditions, to allow early identification and treatment of complications. The most common and important problems in NF1 are cognitive impairment, optic pathway gliomas, plexiform neurofibromas, and orthopaedic issues. Early intervention and tailored educational programs are indicated for learning difficulties. Attention deficit hyperactivity disorder may be amenable to treatment with stimulant medication. A clinical trial is under way to evaluate lovastatin in the treatment of cognitive problems in children with NF1. Chemotherapy with vincristine and carboplatin is the current standard of care for symptomatic optic pathway gliomas, but new agents with improved efficacy are needed. Plexiform neurofibromas may be treated with surgery, but often recur. To date, no medical therapy has proven effective in limiting plexiform neurofibroma growth, but several candidate medications are under consideration in clinical trials. Malignant peripheral nerve sheath tumors may arise in preexisting plexiform neurofibromas, so changes in tumor growth or an increase in pain or focal neurologic deficit should prompt further investigation and early treatment with wide surgical resection, with or without adjuvant chemotherapy or radiotherapy. Specialist surgical intervention may be needed for scoliosis and tibial pseudoarthrosis. In NF2, surgical treatment remains a cornerstone of management for symptomatic progressive vestibular schwannomas, meningiomas, and spinal tumors. Vascular endothelial growth factor inhibitors show promise for the treatment of vestibular schwannomas, with the aim of delaying surgery, and other targeted molecular therapies are becoming available as investigational options. Hearing aids and brainstem and cochlear implants have a role in optimizing functional hearing in some patients. Specialist ophthalmology input should be arranged to monitor for ophthalmologic complications. A coordinated effort is needed to enroll NF1 and NF2 patients in international multicenter clinical trials of promising new pharmacologic agents. Genetic testing is useful for prenatal diagnosis and may be important in understanding individual responses to novel medical therapies in the future. Effective transition to adult services is important, considering the likelihood of further complications in the adult years.

Surgical treatment of giant plexiform neurofibroma associated with pectus excavatum

Plexiform neurofibromas are benign tumors originating from subcutaneous or visceral peripheral nerves, which are usually associated with neurofibromatosis type 1. They are almost always congenital lesions and often cause the surrounding soft tissue and bone to grow aberrantly. We treated a 12-year-old boy who presented with asymmetric pectus excavaum and an anterior chest wall plexiform neurofibroma. The pectus excavaum was corrected by modified Nuss procedure, followed by simultaneous resection of the giant mass. The patient is doing well at the 4 years follow-up visit.