Plexiform Neurofibromas

Medically Reviewed by Christopher Melinosky, MD on March 07, 2024
Written by Keri Wiginton
6 min read

These are rare tumors that grow from nerve cells. They form on the protective cover around your nerves. That’s called the sheath. Most plexiform neurofibromas (PNs) are benign, or non-cancerous. Some -- about 8% to 15% -- do turn into cancer. They’re called malignant peripheral nerve sheath tumors.

Plexiform neurofibromas are typically something you’re born with. But you may not notice them until you’re older, like when you’re a teenager. The tumors tend to get bigger when you go through hormonal changes, like during puberty or pregnancy. You may get more as you age.

They’re usually soft, grow slowly, and can get really big. They can show up anywhere in your body beyond your brain and spinal cord.

You may get plexiform neurofibromas in areas such as your:

  • Face and neck
  • Eye socket
  • Arms and legs
  • Chest, belly, and hips
  • Internal organs

 

People who get plexiform neurofibromas are usually born with a rare genetic disease called neurofibromatosis type 1 (NF1), or von Recklinghausen’s disease. Around 30% to 50% of people who have NF1 will get one or more throughout their life.  

You get NF1 when the gene that helps make neurofibromin changes, or mutates. That’s a protein that stops tumors from growing. If you have the NF1 gene, there’s a 50/50 chance you got it from one of your parents. But this mutation can also happen randomly while you’re in the womb, meaning you can get it even if neither of your parents has the gene.

There’s no evidence that things in your environment trigger NF1 or plexiform neurofibromas. Experts don’t think your diet and lifestyle play a role, either.

Symptoms depend on where your tumor is and how large it grows. In general, plexiform neurofibromas may cause:

  • Pain or numbness
  • Disfigurement
  • Sensation changes
  • Loss of function where the tumor is
  • Other medical problems

Pay attention to how yours look and feel over time. Some warning signs to watch for include:

  • Constant pain
  • Fast growth
  • Hardening
  • Weakness or numbness in the arm or leg where the tumor is

Tell your doctor right away if you have these symptoms, or weight loss and night sweats. This may be a sign a plexiform neurofibroma has turned into cancer.

But they don’t always cause symptoms. Here’s a little more about what might happen if you get one or more in certain areas:

Face, head, or neck. About 50% occur above the shoulders. A tumor on your face or head can change how you look. It can also put pressure on your brain. You may get headaches. Often, kids with NF1 and plexiform neurofibromas have cognitive issues, such as trouble learning.

Tumors around your throat or airways could make it hard to swallow or breathe. One near your eye or ear canal may trigger vision or hearing problems.

Bladder or bowels. You may have symptoms such as:

  • Repeat urinary tract infections
  • Blood in your urine
  • Trouble emptying or controlling your pee
  • Side or back pain
  • Constipation  

Around your spinal cord. You may get a curve in your spine called scoliosis. You may have other nerve problems, too. These include:

  • Muscle weakness in your arms and legs
  • Trouble walking
  • Sensations such as “pins and needles” or burning

 

Your doctor may be able to see some tumors just by looking at you. But you’ll probably need an MRI. That’s when a machine takes detailed pictures of the inside of your body. They may scan your whole body to find tumors they can’t see.

Your doctor will run more tests to check if they’re cancerous.

If you or your child has plexiform neurofibromas, ask your doctor if anyone else in your family should be screened, including an unborn baby. Genetic testing can check for NF1.

Make a list of everything you’d like to know ahead of time. If your child has plexiform neurofibromas, write down their concerns if they’re old enough to describe their symptoms. That’ll help you both remember what to ask when you’re at the appointment.

Here are some questions to get you started:

  • What are all of the treatment options?
  • What are the side effects of drug therapy?
  • Are plexiform neurofibromas dangerous?
  • How can plexiform neurofibromas affect how my child thinks or acts?
  • What resources can help us understand plexiform neurofibromas better?
  • What happens if the plexiform neurofibromas keep growing?
  • What are early signs of cancer?
  • Should I get genetic testing for myself and others in my family?

Your doctor might use a lot of medical terms. It’s OK to stop them when you don’t know what they’re talking about. Ask them to explain something again or refer you to a nurse educator. You should leave your appointment with a better understanding of anything you’re concerned about.

It can be a challenge to manage plexiform neurofibromas or predict how you’ll respond to treatment. But here are some things your doctor may try:

Surgery. In the past, this was the only treatment. But these tumors sometimes grow in a way that makes it really hard or impossible to totally remove them. They can weave their way into multiple nerves or form deep inside tissue or near vital organs. Surgery may do more harm than good. But your doctor will help you decide if this treatment is right for you.

Medication. Your doctor may suggest an oral drug called selumetinib (Koselugo). It’s a kinase inhibitor. That’s a targeted drug designed to block an enzyme that promotes tumor growth. It’s approved for children ages 2 or older who have NF1 and an inoperable tumor that causes symptoms.

Early research shows selumetinib may help about 66% of people with NF1 and PNs. So far, it hasn’t been shown to get rid of tumors completely. But there’s evidence it may do the following:

  • Shrink plexiform neurofibromas by more than 20%
  • Slow or stop future growth
  • Lessen tumor-related pain, disfigurement, and disability
  • Ease medical issues caused by the tumor

Ask your doctor if this drug is right for you or your child. They’ll go over all the pros and cons.

Selumetinib may cause side effects, some of which are serious, such as heart failure or eye damage. It’s not safe to take if you’re pregnant.  

It’s common for people with PNs to have mental health issues, such as depression or anxiety. Ask your doctor to refer you to a social worker or therapist who works with people who have NF1 or similar conditions. Behavioral treatment, such as resilience training, may help.

As a parent or caregiver, you may also feel distress about your child’s condition. It’s important that you seek social support or professional mental health care when you need it.

There isn’t a cure for PNs, and sometimes they can grow back even after treatment. But it’s hard to know if that’ll happen to you or your child.

Ask your doctor how often you should bring your child in for a checkup. They may not suggest surgery or treatment right away. Instead, if your child doesn’t have symptoms, they may take a “watch and wait” approach. They’ll also want to keep track of your child’s:

  • Height and weight
  • Head circumference
  • Sexual maturity
  • Learning or behavioral issues

Adults with NF1 or PNs should get a checkup every year. See your doctor sooner if you notice any new tumors or changes in the old ones. They’ll want to make sure nothing more serious is going on.

You or your child may be able to join a clinical trial for NF1 or plexiform neurofibromas. That’s when researchers test out new treatments. Check for more information at ClinicalTrials.gov.

You may not know anyone else who has NF1 or plexiform neurofibromas. But you’re not alone. Ask your doctor or social worker if there’s a support group in your area. Websites like Neurofibromatosis Network and RareConnect can help you find community, too.