Plexiform neurofibromas
Some neurofibromas can grow in a wide, spreading fashion around large nerves and may feel like a bunch of knots or cords beneath the skin.
These types of growths are called plexiform neurofibromas. About a third of people [with NF1] will have one or more of this type of lump. Sometimes they will be obvious in early life as an area of swelling or fullness but other times they can lie deeper in the body and are harder to detect. They can grow anywhere on the body and, more rarely, on the face.
When they are present near the surface plexiform neurofibromas sometimes grow to a large size. If this is going to happen, it usually does so within the first few years of life.
These tumours can be painful if knocked and can be disfiguring, depending on their size and shape. Less commonly, a plexiform can become cancerous (more on this follows). Any unusual pain in a plexiform neurofibroma should be checked by a doctor.
If a plexiform neurofibroma is painful all the time, grows very rapidly or feels hard rather than soft, medical advice is needed without delay.
Removal of plexiform neurofibromas is difficult and needs the specialist skills of experienced plastic surgeons, orthopaedic or neurosurgeons who specialise in peripheral nerve surgery.
Tumours and cancer
Everyone, whether they have NF1 or not, has a risk of about one in three of developing cancer during their lifetime. People with NF1 have about a one in ten (or 10%) chance of developing a specific cancer related to NF1. Putting this another way, there is a 90% chance of someone NOT developing an NF1-related cancer. Research in this area is continually being updated.
People generally are aware of what is their “normal” state of health whether they have NF1 or not. Having NF1 means it is important to be aware of unusual health changes or symptoms. You should seek medical advice if you experience any new, significant or unusual changes in body habits which do not go away, just as you would if you did not have NF1.
This could include a new or persistent pain, or a change in physical activities.
The small skin neurofibromas never become cancerous. Plexiform neurofibromas are more at risk of turning into nasty lumps (becoming malignant). When this happens the tumour is called a malignant peripheral nerve sheath tumour or MPNST.
The signs to be concerned about if you have a plexiform neurofibroma are: sudden rapid growth where there was previously slow growth; change in texture and the development of unexplained pain, for example where the plexiform neurofibroma was not bumped or knocked. If the pain appears for no apparent reason and does not go away, this should be checked out with your doctor.
MPNSTs can also develop out of the blue. So if anyone with NF1 notices a lump under the skin growing rapidly or that has become painful, they should get it checked by their doctor urgently. Also if they develop unexplained persistent pain, this could be a sign of an internal MPNST.
Again this needs urgent advice from the doctor.
People with NF1 have a slightly increased chance of developing a brain tumour compared to the general population.
Adults who experience persistent new headaches or a change in their usual physical abilities or activities (weakness, numbness, tingling in arms or legs,) or a change in personality or memory should seek medical advice.
Children with NF1 are at risk of two very rare childhood cancers (a rare form of leukaemia and a tumour called a rhabdomyosarcoma that usually grows near the bladder). These are so rare that even in the specialist NF clinics, doctors rarely see these developing. The important thing for parents to know is that if their child is “just not right” they should be asking their doctors if it could be linked to their diagnosis of NF1.
For adults, understanding what is “normal” for you is helpful. If you have symptoms that are unusual for you it is sensible to seek advice and remind your doctors that you have NF1.
Breast cancer
Research shows that women who have NF1 have a slightly higher chance of developing breast cancer during their lifetime. Their breast cancer risk is described as “moderate” and therefore screening should follow national guidelines. At present this means having a breast x-ray (mammogram) each year from the age of 40 years. Your GP can arrange this.
Hypertension (high blood pressure)
Occasionally NF1 can cause high blood pressure. It is recommended that everyone with NF1 should have their blood pressure checked once a year throughout life. Sometimes high blood pressure may not be related to NF1 and it is a common and treatable condition in adults who do not have NF1.
The specific reasons for raised blood pressure linked to NF1 include a lump growing on or near the kidney (phaeochromocytoma) or a narrowing of the artery to the kidney (renal artery stenosis). These can be treated.
Glomus tumour
This is a small benign lump that grows in the nail bed of one or more fingernails and toenails. It is rare. It causes severe pain in the affected finger/toe, which is often worse in the cold.
Sometimes doctors get confused and think the pain is coming from a nerve tumour. Doctors in specialist NF clinics sometimes see patients referred with unexplained hand or foot pain who have undergone lots of scans of the spine and nerves supplying hands and feet which all turn out to be normal. The diagnosis of glomus tumour is made in the clinic by simple means: the doctor presses on the nail bed and the pain is excruciating. Once diagnosed, the tumour can be easily removed, fully relieving the symptoms.
Epilepsy
Everyone is at risk of developing epilepsy during their lifetime. In people with NF1 that risk is slightly increased. Symptoms suggestive of epilepsy should be investigated and treated in the usual
