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Neurofibromatosis is an autosomal dominant condition resulting in the growth of nerve tumours

Suggested approach to neurofibromatosis type 1 osce station

Describing lesions

  • Neurofibromas
    • β€˜There are multiple, well-demarcated brown circular nodules and papules present across the back in a generalized distribution.’          
    • β€˜There are no secondary features (such as crusting, scaling or erosion).’
    • β€˜On palpation, these lesions are soft and non-tender, with some exhibiting the button-hole sign.’
    • β€˜These lesions are consistent with neurofibromas.’
  • CafΓ© au lait spots
    • β€˜There are also irregularly shaped, evenly pigmented, flat brown patches.’
    • β€˜These are characteristic of cafΓ© au lait spots.’
  • Other areas
    • β€˜I would like to look for axillary and inguinal freckling, and abdominal scars (e.g. for phaeochromocytoma surgery).’
  • Conclusion
    • β€˜Given there are 2 or more neurofibromas and 6 or more cafΓ© au lait spots, the likely diagnosis is neurofibromatosis type 1.’
    • β€˜In addition to examining the rest of the skin and taking a full history, I would like to measure blood pressure, do a full neurological exam for signs of spinal cord neurofibromas, examine the eyes for signs of optic nerve gliomas, and use a slit lamp to look for Lisch nodules on the iris.’

If you are allowed to ask the patient questions

  • Family history
  • Eyes, ears, blood pressure
  • Any nerve lesions

Differential diagnosis

  • Neurofibromatosis type 2
  • Tuberous sclerosis (multi-system hamartoma formation)

Types of neurofibromatosis

Type 1 (peripheral) 

  • NF-1 gene defect (chromosome 17) resulting in peripheral neurofibromas (i.e. in skin or subcutaneous tissue)
  • Skin
    • Neurofibromas (2 or more): well-demarcated nodules which are erythematous and varied in size and shape 
    • CafΓ© au lait spots (6 or more): flat patch of asymmetrical darkened skin (brown/black)
    • Axillary freckling
  • Other features
    • Optic nerve glioma β†’ non-correctable visual loss
    • Lisch nodules (iris hamartomas, i.e. brown spots on iris seen with slit lamp)
    • Dorsal root spinal cord tumours
    • Plexiform neurofibromas (diffuse and invasive β†’ bony erosion)

Type 2 (central)

  • Merlin protein gene defect (chromosome 22) resulting in central schwannomas
  • Most common presenting condition is bilateral acoustic neuromas (CN8) causing hearing loss, typically at 20-30 years of age
  • Other conditions include: meningiomas, gliomas, juvenile cataracts
  • Other symptoms include: headache, balance loss, vertigo, facial weakness, deafness, tinnitus
  • Skin symptoms uncommon

Here are some questions

How is neurofibromatosis diagnosed?

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How is neurofibromatosis managed?

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Try a station

  1. Dermatological skin exam
  2. Neurofibromatosis exam
  3. Lots more here

Picture references

Neurofibromatosis back: 2008 Almazi (talk). In public domain. Sourced from:

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