Neurofibromatosis

Vivas and Spotters > Dermatology

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

Suggested approach to neurofibromatosis type 1 osce station

Describing lesions

Neurofibromas
- ‘There are multiple, well-demarcated brown circular nodules and papules present across the back in a generalized distribution.’
- ‘There are no secondary features (such as crusting, scaling or erosion).’
- ‘On palpation, these lesions are soft and non-tender, with some exhibiting the button-hole sign.’
- ‘These lesions are consistent with neurofibromas.’
Café au lait spots
- ‘There are also irregularly shaped, evenly pigmented, flat brown patches.’
- ‘These are characteristic of café au lait spots.’
Other areas
- ‘I would like to look for axillary and inguinal freckling, and abdominal scars (e.g. for phaeochromocytoma surgery).’
Conclusion
- ‘Given there are 2 or more neurofibromas and 6 or more café au lait spots, the likely diagnosis is neurofibromatosis type 1.’
- ‘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
- Café au lait spots (6 or more): flat patch of asymmetrical darkened skin (brown/black)
- Axillary freckling
Other features
- Optic nerve glioma → 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 → 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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Picture references

Neurofibromatosis back: 2008 Almazi (talk). In public domain. Sourced from: https://commons.wikimedia.org/wiki/File:Neurofibromatosis.jpg

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