English Version
M. C. Vallejo, M. P. Jordan

Neurofibromatosis type 2

Neurofibromatosis type 2

Schlüsselwörter Neurofibromatosis type 2; ICD 10: Q85.02; NF2; central nervous system (CNS) tumours
Keywords Neurofibromatosis type 2; ICD 10: Q85.02; NF2; central nervous system (CNS) tumours
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Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterized by central nervous system (CNS) tumors. A mutated allele of the NF2 gene on chromosome 22 accounts for this disorder. Although characterized as autosomal dominant, greater than 50% of cases are new, sporadic mutations. The incidence of NF2 in the general population is 1 in 33,000-40,000, while the prevalence is 1 in 57,000. The average age of onset of symptoms is typically in the early twenties, with the diagnosis being made on average of seven years from onset. The tumors, usually schwannomas, are classically located at the superior vestibular branch of cranial nerve VIII bilaterally. However, up to 40% may occur in the inferior vestibule.  Symptoms of vestibular schwannomas include hearing loss, imbalance, and tinnitus, while late symptoms include headache, mastoid ache, facial twitching, facial numbness, and raised intracranial pressure (ICP). Tumors are often found throughout the CNS, including the brain and spinal cord, although peripheral nerves may also be involved.  The types of tumors involved include schwannomas, meningiomas, ependymomas, and neurofibromas. Schwannomas are benign tumors composed of Schwann cells located outside the nerve, and less than 1% become malignant. Unilateral deafness, with or without tinnitus, is the most common presenting symptom. Other presenting symptoms include tinnitus, muscle weakness or wasting, seizure, vertigo, numbness and tingling, and blindness.  Approximately 70% of patients will have cutaneous lesions as well.

NF2 is genetically and phenotypically different than Neurofibromatosis type 1(NF1).  NF1, or von Recklinghausen’s disease, is an autosomal dominant disorder caused by mutations in the NF1 gene on chromosome 17, and is characterized by café-au-lait spots and freckles, which increase with age, as well as benign tumors and Lisch nodules, which are iris hamartomas.  It is much more common that NF2, having a prevalence of 1 in 2,500-3,500 worldwide.  The benign tumors of NF1 include peripheral neurofibromas and optic gliomas.  Peripheral neurofibromas are tumors of nerve sheaths, and are composed mostly of Schwann cells, along with fibroblasts, perineurial cells, axons, and mast cells.


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