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|Year : 2019 | Volume
| Issue : 7 | Page : 45-46
Surgical dilemmas in the management of peripheral nerve tumors in neurofibromatosis 1
Dhananjaya I Bhat1, Mariano Socolovsky2, Vikram Singh1
1 Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
2 Department of Neurosurgery, University of Buenos Aires School of Medicine, Buenos Aires, Argentina
|Date of Web Publication||23-Jan-2019|
Dr. Dhananjaya I Bhat
Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore - 560 029, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bhat DI, Socolovsky M, Singh V. Surgical dilemmas in the management of peripheral nerve tumors in neurofibromatosis 1. Neurol India 2019;67, Suppl S1:45-6
Neurofibromatosis type-1 (NF-1) is a relatively common inherited disorder with an incidence of 1 in every 2500 to 3000 births. It carries a high predisposition to developing both benign as well as malignant tumors, and has proven associations with optic pathway gliomas, glioblastoma, malignant peripheral nerve sheath tumour, gastrointestinal stromal tumour, breast cancer, leukaemia, pheochromocytoma, duodenal carcinoid tumour, and rhabdomyosarcoma. Peripheral nerve tumors are known to occur in up to 30% of the cases.
In her paper in the study in focus, the author, Dr. Garozzo, provides a detailed description of the varied clinical presentations of peripheral nerve tumors in NF-1. Since a majority of these lesions are benign and asymptomatic, surgery is recommended only for patients with neurological symptoms and suspicion of malignancy. Of note is the reversed ratio of incidence between schwannomas and neurofibromas (1:9) as compared to the general population. The higher incidence of neurofibromas in NF-1 entails a lower possibility of resection without damaging the involved nerve fascicles. In addition, a large proportion (30-50%) of neurofibromas in NF-1 are of the plexiform variety, arising from multiple nerve fascicles and invading the surrounding structures. The presence of multiple lesions and internal plexiform neurofibromas are a further challenge to complete resection. In cases where surgical resection is technically difficult, a role for chemotherapy has been suggested.
The greatest cause for concern in these cases is the development of malignant peripheral nerve sheath tumors (MPNST). Around 50-60% of patients with MPNST have associated NF-1, while 8-13% of patients with NF-1 suffer from an MPNST during their lifetime.,,, Malignant conversion must be suspected in case of rapid increase in size, new onset pain or change in character of pain and decreased mobility. While radiological features are not pathognomonic, a high uptake on FDG-PET can indicate malignancy. Fine needle aspiration cytology or needle biopsy is not advisable in these cases in view of the significant sampling errors. As of now, surgical resection with wide margins (2 cm of tumor free margin) and resection of 5-7 cm of the involved nerve, both proximal and distal to the lesion, remains the procedure of choice. Tendon transfers are preferred for functional recovery. Post-operative external beam radiotherapy has been shown to improve local control, but the same has not translated into an improvement in outcome. Similarly, chemotherapy, although a standard part of the treatment regimen, has not been shown to influence outcome, which remains dismal. The five-year survival rates range from 10-50%, with the prognosis being slightly worse in NF-1.
The relative paucity of information on peripheral nerve tumors in NF-1 poses a challenge to the neurosurgeon, with most of the management being guided along the lines of those for soft tissue sarcomas. A greater understanding of the pathology might lead to more specific treatment protocols. Therefore, we congratulate Dr. Garozzo for sharing her experience and for providing a comprehensive overview of the subject.
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