Neurofibromatosis Flashcards
What is neurofibromatosis?
- genetic condition
- benign tumours of neural origin (neuromas) form around the neural tissues
What’s the problem with neurofibromatosis?
Tumours are benign, but they cause neurological and structural problems
What types of neurofibromatosis are there?
- Type 1 (most common)
- Type 2
What’s NF1 gene?
- chromosome 17
- encodes for protein neurofibromin
- neurofibromin is a tumour suppressor protein
- autosomal dominant inheritance pattern
Diagnostic criteria for neurofibromatosis type 1 (NF1)
- how many?
- mnemonic
- (at least) 2 out of 7
- CRABBING
Criteria for neurofibromatosis type 1 (describe all)
CRABBING
C - cafe-au-lait spots
R - relative with NF1
A - axillary or inguinal freckles
BB - bony dysplasia (e.g. bowing of a long bone, sphenoid wing dysplasia)
I - iris hamartomas (yellow-brown spot on iris)
N - neurofibromas
G - glioma of optic nerve
Diagnosis and investigations in neurofibromatosis
- based on clinical criteria (CRABBING) and no Ix is required to make a clinical Dx
- genetic testing - used when there is doubt
- CT and MRI -> to Ix lesions in the brain, spinal cord
Management of neurofibromatosis
- no treatment will cure or prevent new neurofibromas to grow
- management is to control symptoms, monitor disease and treat complications
Complications of neurofibromatosis 1
- Migraines
- Epilepsy
- Renal artery stenosis causing hypertension
- Learning and behavioural problems (e.g. ADHD)
- Scoliosis of the spine
- Vision loss (secondary to optic nerve gliomas)
- Malignant peripheral nerve sheath tumours
- Gastrointestinal stromal tumour (a type of sarcoma)
- Brain tumours
- Spinal cord tumours with associated neurology (e.g. paraplegia)
- Increased risk of cancer (e.g. breast cancer)
- Leukaemia
Genetics of NF2
- chromosome 22
- protein called merlin - tumour suppressor
(merlin is particularly important in Schwam cells)
- autosomal dominant inheritance
What is NF2 associated with?
Acoustic neuroma
(tumour of auditory nerve innervating inner ear)
Symptoms of acoustic neuroma
- hearing loss
- tinnitus
- balance problems
Where are (apart from inner ear) Schwannomas can form in NF2?
brain, spinal cord
(symptoms depend on location)
Management of NF2 if Schwannoma develop
Surgery to resect tumour (but risk of permanent nerve injury)
What is the cause of bilateral acoustic neuroma?
NF2
