Gliomas in Neurofibromatosis
Neurofibromatosis is an inheritable disease with mainly neurocutaneous manifestations. There are two distinct types of neurofibromatosis; Type I and Type II. Neurofibromatosis type I or NF-1 is also called Von Recklinghausen disease. NF-1 is one of the autosomal dominant disorders exhibiting certain developmental changes in the nervous system, bones, and skin, as a person ages. In addition, it is the most common disease in the class of hamartoma neoplastic syndromes, including tuberous sclerosis, Gardner syndrome, as well as Cowden syndromes. The distinct features of NF-1 are cafe-au-lait macules and neurofibromas. Other types of neurofibromatosis are neurofibromatosis type 2 and schwannomatosis.
The inheritable gene for NF-1 is situated on chromosome 17, encoding for a protein product called neurofibromin. Neurofibromin protein is ubiquitously present in most tissues and normally functions as a tumor suppressor gene by modulating gene expression of RAS gene. The developmental changes occur due to mutation or deletion of this NF-1 gene in an inheritable fashion resulting in the abnormal phenotypic as well as genotypic manifestations associated with the disorder. Pathophysiologically, mutations of the NF-1 gene lead to a loss of expression of neurofibromin which paves the way to tumorigenesis.
The symptoms of NF-1 are very heterogeneous among patients. Most patients develop a benign course of the disease without any major complications. Further based on clinical presentation and spatial parameters, the disorder is classified as segmental NF-1 (neurofibromatosis type 5 or limited to one part of the body) which is due to mosaic NF-1 gene mutation and generalized NF-1(presentations involved with the whole body). The characteristic, main symptoms are:
Inguinal and/or axillary freckling
Neurofibromas are the initial clinical manifestations of NF-1
Tumors of both benign and malignant types occur lifelong in patients with these disorders at an increased rate.
According to the clinical national institutes of health (NIH) criteria, the NF-1 diagnosis is mainly a clinical symptom-based diagnosis. This criterion requires two or more of the following conditions to be fulfilled for accurate diagnosis:
Café-au-lait macules (six or more macules with the dimension of 5 to 15 mm)
Neurofibromas (two or more of any type or one plexiform neurofibroma)
Axillary or inguinal Freckling
Optic gliomas presence
Two or more presence of Lisch nodules
Bony lesions including sphenoid dysplasia, pseudoarthrosis, and others
Family history of a first-degree relative with the disease.
MRI imaging should emphasize the neuroradiological findings consisting of neurofibromatosis bright spots, as well as a high volume of the brain (megalencephaly). However, genetic testing is not mandatory as it can be used for establishing the confusion related to diagnosis through questionable presentations, screening of family members, as well as prenatal screening. It is costly but the figure states that 95% of mutations can be captured via genetic testing in NF-1 clinical diagnosed individuals.
The treatment is mostly symptomatic for various NF-1 manifestations as no definitive management strategies are present. Optic pathway gliomas in children should be treated by chemotherapy with vincristine, carboplatin, and vinblastine as the first-line precise therapy. Radiotherapy in NF-1 disorder is employed when the evolution of secondary tumors occurs.
In addition, malignant peripheral nerve sheath tumors are managed with surgery and radiotherapy. Rhabdomyosarcomas are treated with chemoradiotherapy, along with surgery. Cutaneous and nodular neurofibromas are managed with symptomatic treatment such as analgesics, laser, surgery, electrodissection. The drugs are mainly used for pain, increase in size, weakness, vision loss, or cosmetic concerns, respectively.
Gabapentin drug has sometimes been utilized for the management of itching symptoms of dermal in conjunction with neuropathic pain. Surgery is advised for the removal of plexiform neurofibromas (PN) causing compression of the airway or spinal cord and disfigurement. Selumetinib as a mitogen-activated protein kinase inhibitor was approved for use in PN children of 3 years of age and older. A carbon dioxide laser is further utilized to remove most disfiguring neurofibromas. Moreover, the symptomatic manifestation of seizures or epilepsy should be thoroughly monitored to follow a neurosurgical intervention procedure. The learning or cognitive disabilities in children along with the developmental neurologic impairment should be managed by speech, physical, and occupational therapists. Subsequent management of skeletal anomalies in some patients such as dysplasia, pseudoarthrosis, and scoliosis should be performed efficiently by an orthopedic surgeon. Nutritional supplements are also useful in the form of Vitamin D and calcium use for individuals with osteopenia and osteoporosis. Psychological counseling and therapy can assist with the improvement of quality of life by enhancing the psyche and psychosocial functioning of the affected individuals.