Neurofibromatosis is a genetic condition causing tumours to grow along the nerves.
The disorders are known as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). NF1 is the most common type of neurofibromatosis.
Symptoms include café-au-lait spots of tan or light brown skin and soft fleshy growths under the skin.
NF1 can lead to high blood pressure, curvature of the spine or scoliosis, learning difficulties and behavioural problems.
NF2 can cause hearing loss, tinnitus and balance problems.
What causes neurofibromatosis?
Neurofibromatosis is often inherited (passed on by family members through our genes), but in around 50% of people newly diagnosed with the disorder have no family history of the condition, which can arise spontaneously through a mutation (change) in the genes. Once this change has taken place, the mutant gene can be passed on to future generations.
What are the symptoms of neurofibromatosis?
The following symptoms can appear in people with Nf1:
- Several (usually six or more) café-au-lait spots.
- Multiple freckles in the armpit or groin area.
- Tiny growths (brown spots) in the iris (coloured area) of the eye. These are called Lisch nodules and usually do not affect eyesight.
- Neurofibromas occur on or under the skin, sometimes even deep within the body. These are benign (harmless) tumours, however, in rare cases, they can turn malignant or cancerous.
- Bone deformities including a twisted spine (scoliosis) or bowed legs.
- Tumours along the optic nerve, which may cause eyesight problems.
- Nerve-related pain
People with Nf2 often display the following symptoms:
How is neurofibromatosis diagnosed?
Neurofibromatosis is diagnosed using a number of tests, including:
- Physical examination.
- Medical history.
- Family history.
- Computerised tomography (CT) scans.
- Magnetic resonance imaging (MRI).
- Biopsy of neurofibromas.
- Eye tests.
- Tests for particular symptoms, such as hearing or balance tests.
- Genetic testing (available for families with documented cases of Nf1 and Nf2).
To receive a diagnosis of Nf1, you must have two of the following symptoms:
- Six or more café-au-lait spots that are 1.5 cm (15mm) or larger in adults or 0.5 cm (5mm) or larger in children.
- Two or more neurofibromas (bumps under or on the skin) of any type or one or more plexiform neurofibroma (a neurofibroma that develops where lots of nerve branches meet).
- Freckling in the armpit or groin.
- Optic glioma (tumour of the optic pathway).
- Two or more Lisch nodules.
- A distinctive bony lesion, such as bowing of the lower leg.
- A family history of Nf1.
To be diagnosed with Nf2, you must have:
- Bilateral (on both sides) vestibular schwannomas, also known as acoustic neuromas. These are benign tumours that develop from the balance and hearing nerves supplying the inner ear.
- Family history of Nf2 (first degree family relative) plus unilateral (on one side) vestibular schwannomas or any two of the following health conditions:
- Meningioma (tumour that occurs in the meninges, the membranes that cover and protect the brain and spinal cord).
- Glioma (tumour of the brain that begins in glial cells, which are those that surround and support nerve cells).
- Juvenile cataracts.