There are two types of Neurofibromatosis:
The neurofibromatoses can be distinguished according to type and distribution of hamartomatous lesions. Neurofibromatosis type 1 (NF1) is a common and well known disorder first described by von Recklinghausen in 1849.
- Incidence: 1/2500-1/4000
- Male= Female
- There is considerable phenotypic variability between members of the same family.
Patients with NF1 usually present in childhood with café-au-lait patches or in adulthood with neurofibromas.
NF1 Diagnostic Criteria [ ]=% of individuals with features
Patients must have 2 or more of the following:
- Café-au-lait patches 6 or more 5mm prepubertal, >15mm in an adult) [>99%]
- Axillary or inguinal freckling [85%]
- Neurofibromas (2 or more cutaneous/ subcutaneous) [>99%]
- Plexiform neurofibromas (1 or more) [30-50%]
- Lisch nodules (benign iris hamartomas see on slit lamp) (2 or more) [95%]
- Optic pathway glioma [15% total, 5% symptomatic]
- Bony dysplasia (Sphenoid wing/ long bone or pseudarthrosis) [2%]
- First degree relative with NF1
- Mild cognitive impairment [30-60%]
- Scoliosis [11%]
- Malignant peripheral nerve sheath tumours [8-13% lifetime risk]
- Cerebral gliomas [2%]
- Raised blood pressure may be due to benign essential hyper-tension, renal artery stenosis or phaeochromocytoma [2%]
Neurofibromatosis type 2 (NF2) is a much rarer condition and characterised by the formation of VIIIth cranial nerve vestibular schwannomas.
- Incidence: 1/40 000-1/100 000
- Typically bilateral vestibular schwannomas, deafness and tinnitus
- Neurological features secondary to CNS tumour
- Cataracts (juvenile)
- CALS: 4% of patients have >3, 0% of patients have >6
- In contrast to NF1, plexiform neurofibromas, axillary freckling and lisch nodules are rare
- CNS tumours and surgical sequelae