INTRODUCTION

Neurofibromatosis type 1 (NF1) is an autosomal dominantly inherited condition seen in one of 4000 live births, predisposing to peripheral and central neurofibromas. Spinal tumors are seen in 40% of cases with NF1 and only 2% will develop symptoms, and among those who develop symptoms where 33% showed intradural extramedullary location. Thoracic spinal dumbbell neurofibroma is even rarer, and cases that extend to obliterate the posterior mediastinum even more so, with the case presented being the largest in size documented to date.

A 34-year-old female presented since childhood clinical findings consistent with Neurofibromatosis Type I: generalized cafe-au-lait macules, axillary freckling, cutaneous neurofibromas, two iris Lisch nodules identified via slit lamp examination, and anterolateral bowing of the right tibia, and no known parental history of Neurofibromatosis Type I. Prior to admission, the patient presented with progressive loss of motor strength of the lower extremities, and progressive dyspnea. Work-up revealed a Thoracic Intradural Extramedullary Neurofibroma extending to the Right Posterior Mediastinum measuring 15.3 cm x 12.9 cm x 9.7 cm in the thoracic cavity compressing the right lung and bronchus. An extensive two stage surgery was contemplated involving an initial resection of the Intradural mass, with spine instrumentation for support, and subsequent resection of the mediastinal extension. However, complications from the compressing tumor: complete cord transection syndrome causing spinal autonomic dysfunction, lung and airway compromise causing prolonged intubation and difficulty in weaning from mechanical ventilatory support, extensive thrombus formation in the right jugular vein, and nosocomial infections all created compounding difficulties for the surgical technique and anesthetic plan.

Cornerstone management for dumbbell spinal neurofibromas involves their total removal. The best results are obtained in patients showing minimal neurological deficits during the preoperative period. However, little improvement may be expected from patients who develop complete transection syndrome during the postoperative period. Concurrent medical management to prepare the patients are equally important. The multi-subspecialty approach required in managing these cases entails a good balance between the disability before the surgery, anticipated outcomes, and quality of life of the patients.

OBJECTIVE: To summarize the gene therapy strategies for neurofibromatosis type 1 (NF1) and related research progress. METHODS: The recent literature on gene therapy for NF1 at home and abroad was reviewed. The structure and function of the NF1 gene and its mutations were analyzed, and the current status as well as future prospects of the transgenic therapy and gene editing strategies were summarized. RESULTS: NF1 is an autosomal dominantly inherited tumor predisposition syndrome caused by mutations in the NF1 tumor suppressor gene, which impair the function of the neurofibromin and lead to the disease. It has complex clinical manifestations and is not yet curable. Gene therapy strategies for NF1 are still in the research and development stage. Existing studies on the transgenic therapy for NF1 have mainly focused on the construction and expression of the GTPase-activating protein-related domain in cells that lack of functional neurofibromin, confirming the feasibility of the transgenic therapy for NF1. Future research may focus on split adeno-associated virus (AAV) gene delivery, oversized AAV gene delivery, and the development of new vectors for targeted delivery of full-length NF1 cDNA. In addition, the gene editing tools of the new generation have great potential to treat monogenic genetic diseases such as NF1, but need to be further validated in terms of efficiency and safety. CONCLUSION Gene therapy, including both the transgenic therapy and gene editing, is expected to become an important new therapeutic approach for NF1 patients.
Humans ; Neurofibromatosis 1/pathology* ; Neurofibromin 1/metabolism* ; GTPase-Activating Proteins ; Mutation ; Genetic Predisposition to Disease ; Genetic Therapy

OBJECTIVE: To explore the types of NF1 gene variants and clinical characteristics among patients with Neurofibromatosis type I (NF1). METHODS: Clinical data of 12 patients diagnosed at Ningbo Women and Children's Hospital between December 2019 and May 2022 were retrospectively analyzed. The probands and their family members were subjected to high-throughput sequencing, and candidate variants were verified by Sanger sequencing and chromosome microarray analysis. RESULTS: The 12 patients had ranged from 4 months to 27 years old, with a male-to-female ratio of 2 : 1. Cafè-au-lait spots were found in all patients. 83.3% of them also had axillary and/or inguinal freckling, 58.3% had neurofibromas, and 16.7% had congenital pseudarthrosis of the tibia. Five types of NF1 gene variants were identified in the patients, including 5 nonsense variants, 4 frameshift variants, 1 missense variant, 1 splice variant, 1 large deletion involving the whole gene. Six patients were found to harbor de novo variants, 2 had inherited the variants from their parents, and 4 were not verified for their parental origin. The c.3379del (p.Thr1127Glnfs*15) and c.6628_6629del (p.Glu2210Thrfs*10) variants were unreported in literature and databases. CONCLUSION Most NF1 patients may present with Cafè-au-lait spots initially and are due to pathogenic variant of the NF1 gene. High-throughput sequencing can efficiently identify such variants among the patients and enable the definite diagnosis.
Child ; Humans ; Female ; Male ; Neurofibromatosis 1/diagnosis* ; Cafe-au-Lait Spots/diagnosis* ; Genes, Neurofibromatosis 1 ; Retrospective Studies ; Frameshift Mutation

Humans ; Neurofibromatosis 1/pathology*

Humans ; Child ; Neurofibromatosis 1/drug therapy* ; Benzimidazoles/therapeutic use*

Objective: To summarize the clinical characteristics of epileptic seizure associated with neurofibromatosis type 1 (NF1). Methods: From January 2017 to July 2023 at Children's Hospital Capital Institute of Pediatrics, medical records of patients with both NF1 and epileptic seizure were reviewed in this case series study. The clinical characteristics, treatment and prognosis were analyzed retrospectively. Results: A total of 15 patients(12 boys and 3 girls) were collected. Café-au-lait macules were observed in all 15 patients. There were 6 patients with neurodevelopmental disorders and the main manifestations were intellectual disability or developmental delay. The age at the first epileptic seizure was 2.5 (1.2, 5.5) years. There were various seizure types, including generalized tonic-clonic seizures in 8 patients, focal motor seizures in 6 patients, epileptic spasm in 4 patients, tonic seizures in 1 patient, absence in 1 patient, generalized myoclonic seizure in 1 patient and focal to bilateral tonic-clonic seizure in 1 patient. Among 14 patients whose brain magnetic resonance imaging results were available, there were abnormal signals in corpus callosum, basal ganglia, thalamus or cerebellum in 6 patients, dilated ventricles of different degrees in 3 patients, blurred gray and white matter boundary in 2 patients, agenesis of corpus callosum in 1 patient and no obvious abnormalities in the other patients. Among 13 epilepsy patients, 8 were seizure-free with 1 or 2 antiseizure medications(ASM), 1 with drug resistant epilepsy was seizure-free after left temporal lobectomy, and the other 4 patients who have received 2 to 9 ASM had persistent seizures. One patient with complex febrile convulsion achieved seizure freedom after oral administration of diazepam on demand. One patient had only 1 unprovoked epileptic seizure and did not have another seizure without taking any ASM. Conclusions: The first epileptic seizure in NF1 patients usually occurs in infancy and early childhood, with the main seizure type of generalized tonic-clonic seizure and focal motor seizure. Some patients have intellectual disability or developmental delay. Most epilepsy patients achieve seizure freedom with ASM.
Male ; Female ; Humans ; Child, Preschool ; Child ; Neurofibromatosis 1/diagnosis* ; Retrospective Studies ; Intellectual Disability ; Electroencephalography ; Epilepsy/etiology* ; Seizures/etiology*

A 16.5-year-old Indian female presented with secondary amenorrhoea, cubitus valgus, scoliosis and multiple lentigines on the face. Karyotyping revealed mosaic Turner syndrome (TS) with 45, X/46, X iXq. She also had multiple café-au-lait macules and axillary freckles but no neurofibroma and did not fulfil the classic criteria for diagnosis of Neurofibromatosis-1(NF1). Many of her macules were smaller than 15 mm in diameter, which might be due to her hypoestrogenic state. However, exome-sequencing found a pathologic variant consistent with NF1. She was started on daily oral estrogen, and oral progesterone for 10 days every month with close monitoring for neurofibroma and/or glioma expansion. Co-occurrence of NF1 and TS is extremely rare, TS and NF1 can both affect growth and puberty, cause different cutaneous and skeletal deformities, hypertension, vasculopathy and learning disabilities. Our case highlights the need for genetic testing in some cases with NF1 who do not strictly fulfil the NIH diagnostic criteria. We also emphasize the need for close monitoring during therapy with growth hormone, estrogen and progesterone due to the potential risk of tumour expansion in NF1.
Turner syndrome ; Neurofibromatosis 1 ; NF-1

Humans ; Neurofibromatosis 1 ; Larynx ; Laryngeal Neoplasms/surgery*

Objective: To investigate the clinicopathological, immunophenotypic, and genetic features of malignant peripheral nerve sheath tumor (MPNST). Methods: Twenty-three cases of MPNST were diagnosed at the Jiangsu Province Hospital (the First Affiliated Hospital of Nanjing Medical University), China, between January 2012 and December 2022 and thus included in the study. EnVision immunostaining and next-generation sequencing (NGS) were used to examine their immunophenotypical characteristics and genomic aberrations, respectively. Results: There were 10 males and 13 females, with an age range of 11 to 79 years (median 36 years), including 14 cases of neurofibromatosis type I-associated MPNST and 9 cases of sporadic MPNST. The tumors were located in extremities (7 cases), trunk (4 cases), neck and shoulder (3 cases), chest cavity (3 cases), paraspinal area (2 cases), abdominal cavity (2 cases), retroperitoneum (1 case), and pelvic cavity (1 case). Morphologically, the tumors were composed of dense spindle cells arranged in fascicles. Periphery neurofibroma-like pattern was found in 73.9% (17/23) of the cases. Under low magnification, alternating hypercellular and hypocellular areas resembled marbled appearance. Under high power, the tumor cell nuclei were irregular, presenting with oval, conical, comma-like, bullet-like or wavy contour. In 7 cases, the tumor cells demonstrated marked cytological pleomorphism and rare giant tumor cells. The mitotic figures were commonly not less than 3/10 HPF, and geographic necrosis was often noted. Immunohistochemically, tumor cells were positive for S-100 (14/23, 60.9%) and SOX10 (11/23, 47.8%). The loss of the CD34-positive fibroblastic network encountered in neurofibromas was observed in 14/17 of the MPNST cases. The loss of H3K27me3 expression was observed in 82.6% (19/23) of the cases. Moreover, SDHA and SDHB losses were presented in one case. NGS revealed that NF1 gene loss of function (germline or somatic) were found in all 5 cases tested. Furthermore, four cases accompanied with somatic mutations of SUZ12 gene and half of them had somatic mutations of TP53 gene, while one case with germline mutation in SDHA gene and somatic mutations in FAT1, BRAF, and KRAS genes. Available clinical follow-up was obtained in 19 cases and ranged from 1 to 67 months. Four patients died of the disease, all of whom had the clinical history of neurofibromatosis type Ⅰ. Conclusions: MPNST is difficult to be differentiated from a variety of spindle cell tumors due to its wide spectrum of histological morphology and complex genetic changes. H3K27me3 is a useful diagnostic marker, while the loss of CD34 positive fibroblastic network can also be a diagnostic feature of MPNST. NF1 gene inactivation mutations and complete loss of PRC2 activity are the common molecular diagnostic features, but other less commonly recurred genomic aberrations might also contribute to the MPNST pathogenesis.
Female ; Male ; Humans ; Child ; Adolescent ; Young Adult ; Adult ; Middle Aged ; Aged ; Neurofibrosarcoma ; Neurofibromatosis 1 ; Histones ; Genes, p53 ; Nerve Sheath Neoplasms

Objective: To explore the long-term effect of combined surgery for the treatment of congenital tibial pseudarthrosis in children. Methods: The clinical data of 44 children with congenital tibial pseudarthrosis who underwent combined surgery (tibial pseudarthrosis tissue resection, intramedullary rod fixation, Ilizarov external fixator fixation, wrapped autologous iliac bone graft) from August 2007 to October 2011 at the Department of Pediatric Orthopedics, Hunan Children's Hospital were collected retrospectively. There were 33 males and 11 females. The age at the time of surgery was (3.7±2.2)years (range:0.6 to 12.4 years), including 25 cases under 3 years old and 19 cases above 3 years old.Among them, 37 cases were complicated with neurofibromatosis type 1.The operation status, postoperative complications and follow-up results were recorded. Results: The follow-up time after surgery was (10.9±0.7)years (range:10 to 11 years).Thirty-nine out of 44 patients (88.6%) achieved initial healing of tibial pseudarthrosis, with an average healing time of (4.3±1.1)months (range:3 to 10months).In the last follow-up, 36 cases (81.8%) had unequal tibial length, 20 cases (45.4%) had refractures, 18 cases (40.9%) had ankle valgus, 9 cases (20.4%) had proximal tibial valgus, and 11 cases (25.0%) had high arched feet.Nine cases (20.4%) developed distal tibial epiphyseal plate bridging.17 cases (38.6%) had abnormal tibial mechanical axis.Seven cases (15.9%) developed needle infection, and one case (2.3%) developed tibial osteomyelitis. 21 patients (47.7%) had excessive growth of the affected femur.Five patients (11.3%) had ankle stiffness, and 34 patients (77.2%) had intramedullary rod displacement that was not in the center of the tibial medullary cavity.Among them, 8 cases (18.1%) protruded the tibial bone cortex and underwent intramedullary rod removal.18 children have reached skeletal maturity, while 26 children have not been followed up until skeletal maturity. Conclusion: Combined surgery for the treatment of congenital pseudarthrosis of the tibia in children has a high initial healing rate, but complications such as unequal tibia length, refracture, and ankle valgus occur during long-term follow-up, requiring multiple surgical treatments.
Male ; Female ; Humans ; Child ; Child, Preschool ; Pseudarthrosis/congenital* ; Follow-Up Studies ; Retrospective Studies ; Tibia/surgery* ; Neurofibromatosis 1 ; Tibial Fractures/surgery*