Neurological malignancies in neurofibromatosis type 1

Genotype-Phenotype Correlations in Neurofibromatosis Type 1: A Single-Center Cohort Study

Simple Summary

Neurofibromatosis type 1 (NF1) is a complex disorder characterized by a multisystem involvement and cancer predisposition. It is caused by genetic variants in NF1, a large tumor suppressor gene encoding a cytoplasmatic protein (neurofibromin) with a regulatory role in essential cellular processes. Genotype–phenotype correlations in NF1 patients are so far elusive. We retrospectively reviewed clinical, radiological, and genetic data of 583 individuals with at least 1 National Institutes of Health (NIH) criterion for NF1 diagnosis, including 365 subjects fulfilling criteria for the diagnosis. Novel genotype–phenotype correlations were identified through uni- and multivariate statistical analysis. Missense variants negatively correlated with neurofibromas. Skeletal abnormalities were associated with frameshift variants and whole gene deletions. The c.3721C>T; p.(R1241*) variant positively correlated with structural brain alterations, whereas the c.6855C>A; p.(Y2285*) variant was associated with a higher prevalence of Lisch nodules and endocrinological disorders. These novel NF1 genotype–phenotype correlations may have a relevant role in the implementation of patients’ care.

Abstract

Neurofibromatosis type 1 (NF1) is a proteiform genetic condition caused by pathogenic variants in NF1 and characterized by a heterogeneous phenotypic presentation. Relevant genotype–phenotype correlations have recently emerged, but only few pertinent studies are available. We retrospectively reviewed clinical, instrumental, and genetic data from a cohort of 583 individuals meeting at least 1 diagnostic National Institutes of Health (NIH) criterion for NF1. Of these, 365 subjects fulfilled ≥2 NIH criteria, including 235 pediatric patients. Genetic testing was performed through cDNA-based sequencing, Next Generation Sequencing (NGS), and Multiplex Ligation-dependent Probe Amplification (MLPA). Uni- and multivariate statistical analysis was used to investigate genotype–phenotype correlations. Among patients fulfilling ≥ 2 NIH criteria, causative single nucleotide variants (SNVs) and copy number variations (CNVs) were detected in 267/365 (73.2%) and 20/365 (5.5%) cases. Missense variants negatively correlated with neurofibromas (p = 0.005). Skeletal abnormalities were associated with whole gene deletions (p = 0.05) and frameshift variants (p = 0.006). The c.3721C>T; p.(R1241*) variant positively correlated with structural brain alterations (p = 0.031), whereas Lisch nodules (p = 0.05) and endocrinological disorders (p = 0.043) were associated with the c.6855C>A; p.(Y2285*) variant. We identified novel NF1 genotype–phenotype correlations and provided an overview of known associations, supporting their potential relevance in the implementation of patient management.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

Retrospective Multicentric Study on Non-Optic CNS Tumors in Children and Adolescents with Neurofibromatosis Type 1

s: The natural history of non-optic central nervous system (CNS) tumors in neurofibromatosis type 1 (NF1) is largely unknown. Here, we describe prevalence, clinical presentation, treatment, and outcome of 49 non-optic CNS tumors observed in 35 pediatric patients (0-18 years). Patient- and tumor-related data were recorded. Overall survival (OS) and progression-free survival (PFS) were evaluated. Eighteen patients (51%) harbored an optic pathway glioma (OPG) and eight (23%) had multiple non-optic CNS lesions. The majority of lesions (37/49) were managed with a wait-and-see strategy, with one regression and five reductions observed. Twenty-one lesions (42.9%) required surgical treatment. Five-year OS was 85.3%. Twenty-four patients progressed with a 5-year PFS of 41.4%. Patients with multiple low-grade gliomas progressed earlier and had a lower 5-year PFS than those with one lesion only (14.3% vs. 57.9%), irrespective of OPG co-presence. Non-optic CNS tumors are common in young patients with NF1. Neither age and symptoms at diagnosis nor tumor location influenced time to progression in our series. Patients with multiple lesions tended to have a lower age at onset and to progress earlier, but with a good OS.

[Hereditary predisposition to tumors of the central and peripheral nervous systems]

Some tumors of the central and peripheral nervous system may be associated with a cancer predisposition syndrome, either hereditary or occurring de novo. Such a syndrome is usually associated with multiple tumors occurring early in life. Patients with neurofibromatosis type 1 present with multiple neurofibromas, especially of the plexiform type (which may transform into malignant peripheral nerve sheath tumor), and pilocytic astrocytomas of the optic pathways. Neurofibromatosis type 2 patients present with multiple schwannomas (typically bilateral vestibular schwannomas), meningiomas, and ependymomas. Li-Fraumeni syndrome (germline TP53 mutation) is associated with choroid plexus tumors (carcinomas), medulloblastomas, and diffuse astrocytomas. Multiple hemangioblastomas are characteristic of von Hippel-Lindau syndrome while subependymal giant cell astrocytomas are pathognomonic of tuberous sclerosis complex. Dysplastic cerebellar gangliocytomas of adult patients occur in Cowden syndrome. Turcot syndrome overlaps with constitutional mismatch repair deficiency syndrome (CMMRD), which is associated with giant cell glioblastomas. Rhabdoid tumor predisposition syndrome (germline mutation of SMARCB1/INI1) is associated with atypical teratoid/rhabdoid tumors. Tumors arising in the setting of a cancer predisposition syndrome develop along specific genetic pathways. Some histopathological and immunohistochemical characteristics of these tumors may point toward such a syndrome. The diagnosis of a cancer predisposition syndrome is of tremendous importance to the patients and their families who require genetic counseling and long-term follow-up.

Giant Malignant Peripheral Nerve Sheath Tumor of the Head and Neck: A Case Report and Literature Review

Malignant peripheral nerve sheath tumor (MPNST) is a malignant soft tissue sarcoma with high mortality, low morbidity, and poor prognosis. The MPNST occurs mostly in the limbs and torso, and rarely in the head and neck. However, MPNST is insensitive to radiotherapy and chemotherapy, and complete surgical resection with negative margin is the most important and effective strategy. We present a case of MPNST in the head and neck. The tumor invades the left temporal bone, petrous bone, and mastoid bone, and compression changes in the focal cerebellum and sigmoid sinus. The patient underwent the left temporal region tumor resection + surgical reconstruction with temporalis muscle flap and pectoralis major myocutaneous flap. Adjuvant radiotherapy (55 Gy) was given after surgery, and there were no local recurrence and distant metastasis after 31-month follow-up.