Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1), also known as von Recklinghausen disease, is a multisystem neurocutaneous disorder and the most common phakomatosis. Additionally, it is also one of the most common inherited CNS disorders, autosomal dominant disorders and inherited tumour syndromes. 

Individual systemic manifestations are discussed individually: 

The remainder of this article pertains to a general discussion of neurofibromatosis type 1 (NF1). 

Neurofibromatosis affects 1:2500-3000 individuals 3. In half of cases, the disease is inherited as an autosomal dominant condition. In the other 50% of cases the disease is due to a new mutation 6. There is variable expression but 100% penetrance by 5 years of age 6.

As is the case with many phakomatoses, NF1 results in a variety of abnormalities of variable severity. To make the clinical diagnosis two or more of following are required 2:

In addition ~45% (range 30-60%) of patients have learning disabilities.

It is important to consider that NF1 has a much earlier age of onset than schwannomatosis and NF2, with approximately 50% of patients meeting the diagnostic criteria for NF1 by the age of 1 year and approximately 97% meeting the criteria by the age of 8 years 10

Neoplasms

It should come as no surprise that a disease due to inactivation of a tumour suppressor gene (see below) is also associated with increased incidence of numerous tumours 1-6:

The NF1 gene locus is on chromosome 17q11.2 and the gene product  is neurofibromin, acts as a tumour suppressor; inactivation of the gene thus predisposes to tumour development 6.

The disease primarily is a hamartomatous disorder that involves the ectoderm and mesoderm. Usually three types of neurofibromas occur in this disorder and are distinguished on the basis of their gross and microscopic appearances. 

  • localised neurofibroma (cutaneous neurofibroma): the most common type, is a focal lesion that typically is located in the dermis and subcutis
  • diffuse neurofibroma (subcutaneous neurofibroma): localised in the subcutis, usually in the head and neck region. 
  • plexiform neurofibroma: considered pathognomonic if present ; they may be seen in virtually any location but usually occur in the neck, pelvis, and extremities 
Breast
Central nervous system
  • FASI (focal areas of signal intensity): occur in deep white matter and basal ganglia or corpus callosum 5, areas of T2/FLAIR hyperintensity with no contrast enhancement
  • optic nerve glioma or optic pathway glioma (may manifest as enlarged optic foramen)
  • progressive sphenoid wing dysplasia
  • lambdoid suture defects
  • dural calcification at vertex
  • moya moya phenomenon (rare)
  • buphthalmos
Cutaneous
  • cutaneous and subcutaneous neurofibromas: benign peripheral nerve sheath tumours
Skeletal
Thoracic
Vascular

No single treatment exists, and a combination of supportive and surgical therapies are employed depending on the specific tumours and anomalies present. 

Although prognosis is very variable, overall patients with neurofibromatosis type I have a life expectancy approximately half that of non affected individuals, usually succumbing to tumours or cardiovascular complications 8.  


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Article Information

rID: 1725
Section: Syndromes
Synonyms or Alternate Spellings:
  • Neurofibromatosis type 1 (NF1)
  • Neurofibromatosis type 1
  • NF1
  • von Recklinghausen disease
  • neurofibromatosis type I
  • Type neurofibromatosis

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    Cor T2
    Case 1: plexiform neurofibroma
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    Case 2: plexiform neurofibroma
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    Case 2: neurofibromasta
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    Neurofibromatosis...
    Case 4: cutaneous neurofibromata
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    Case 5: with optic nerve gliomas
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    Case 6: with cord compression
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    Plexiform neurofi...
    Case 7: hemifacial hypertrophy
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    NF1

Multiple ner...
    Case 8: ribbon-ribs deformity
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    Case 9: neurofibromas in breast and axilla
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    Case 10: sphenoid wing dysplasia
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    Case 11: with ulnar pseudoarthrosis
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    T2 AXI: Plexiform...
    Case 13: plexiform neurofibroma of thigh
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    Case 14: neurofibromas
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    Case 15: neurofibromas dorsal nerve roots
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    Case 17: intraspinal neurofibroma
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    Case 18: plexiform neurofibroma of foot
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    Case 19: plexiform neurofibroma femoral nerve
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    There is a parave...
    Case 20
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    Case 21
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    Case 22: huge abdominal and retroperitoneal plexiform neurofibromatosis
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