Neurofibromatosis type 1 (NF1) is a genetic condition that raises your risk of tumors, including benign plexiform neurofibromas (PN), which grow along tissues that cover nerves. PN often can’t be fully removed, but getting treatment may help ease symptoms.

Although anyone can potentially develop a PN, this type of tumor is more common in people with NF1. More research is needed to learn exactly how common they are.

“Probably about half of people with NF1 will have a plexiform neurofibroma,” said Justin Jordan, MD, MPH, FAAN, director of the Family Center for Neurofibromatosis at Massachusetts General Hospital and associate professor of neurology at Harvard Medical School in Boston, MA.

“It tends to be something that’s present early on in life and may grow at the same pace as the child’s growth or faster than the child’s growth.”

Children with NF1 may already have a PN by the time they’re born, although it may not cause noticeable symptoms until years later. It’s possible to develop more than one PN.

PN typically require lifelong monitoring and treatment to manage potential symptoms and complications.

Read on to learn more about NF1-associated PN (NF1-PN).

NF1 is a genetic condition that raises your risk of benign (noncancerous) and malignant (cancerous) tumors.

Neurofibromas are tumors that develop in nerve sheaths, which are layers of tissue that surround and protect nerves. PN are the most complex type of neurofibroma. They typically affect bundles of nerves or long portions of a single nerve.

The National Organization for Rare Disorders reports that up to 50% of people with NF1 have at least one PN. These tumors are often present at birth or develop in early childhood and get larger over time.

PN may develop in any part of the body outside of the brain and spinal cord. They may form near the surface of the skin or deeper inside the body.

Most PN are benign, meaning they’re not cancerous and don’t spread from the nerve sheath to other types of tissues or organs. But they may still grow in ways that affect other tissues and organs by pressing on them.

Some PN eventually change into a type of cancerous tumor known as a malignant peripheral nerve sheath tumor (MPNST), which can quickly spread to other tissues or organs.

The genetic mutation that causes NF1 may be passed from a parent to a child or develop spontaneously in someone with no family history of the condition.

PN can cause a variety of symptoms, which vary depending on the location and size of the tumor.

“They can be disfiguring or painful,” explained Jordan. “With the involvement of nerves, these tumors can also cause a host of other symptoms.”

PN near the surface of the skin may cause a noticeable lump. This lump may get quite large over time. The skin over it may be darker in color or thicker than the surrounding skin.

If a PN grows deeper inside the body, it may not cause a noticeable lump.

Other potential symptoms include:

  • pain
  • itching
  • irritation
  • numbness
  • weakness
  • trouble controlling or coordinating movement

If a PN is pressing on bones or other tissues or organs, it may cause complications such as:

  • atypical bone growth
  • difficulties with breathing, swallowing, or eating
  • hearing or vision changes
  • bladder or bowel problems
  • bleeding

If you have NF1-PN, you may also have other symptoms due to NF1 that are not caused by the PN.

Potential symptoms of NF1 include:

  • freckles in unusual locations, like your armpit and groin
  • multiple tan or brown birthmarks, known as café-au-lait spots
  • Lisch nodules, which cause small clumps of unusual color in the colored part of the eye
  • atypical bone development, such as an unusually curved spine or bowed legs
  • macrocephaly, or a large head
  • shorter than average height
  • learning disabilities
  • other types of tumors

These symptoms may be noticeable before symptoms of a PN develop.

Children with NF1 often develop unusual freckles or café-au-lait spots by the time they’re 1 year old.

Roughly 50% of children with NF1 develop Lisch nodules by the time they are 5 years old.

People with NF1 also have an increased risk of other types of noncancerous and cancerous tumors.

Most people who have NF1 receive the diagnosis in early childhood.

To diagnose NF1, a doctor will look for the following:

  • six or more light brown spots on the skin, called café-au-lait spots
  • two or more soft, pea-sized bumps on or under the skin (cutaneous neurofibromas) or one larger PN
  • freckles in the armpit or groin
  • clumps of unusual color in their eye
  • a tumor in the optic pathway
  • atypical bone growth
  • a first-degree relative with the condition

Their doctor will conduct a physical exam and ask about their personal and family medical history. They may also order blood tests to check for genetic markers of NF1 or other health conditions.

If you or your child has NF1, let a doctor know if any lumps form under the skin or other potential signs or symptoms of a tumor develop.

Your doctor may perform a biopsy, which involves collecting a sample of tissue to examine under a microscope. They may also order other tests, such as blood tests and imaging tests.

This can help them learn whether the symptoms are caused by a PN, another type of tumor, or another health condition that may or may not be related to NF1.

The treatment for NF1-PN depends on a number of factors, such as:

  • the severity of symptoms
  • the number, size, and location of tumors
  • whether complications have developed

Common treatments are described below.

It’s also important to attend regular check-ups with a doctor to monitor NF1-PN for signs of changes, including potential signs that a PN has changed into the cancer MPNST.

You can search for a doctor who specializes in NF1 using an online directory from the Children’s Tumor Foundation or the Neurofibromatosis Network.

Active surveillance

If NF1-PN is causing only mild symptoms or no noticeable symptoms, your doctor may recommend active surveillance. This is sometimes known as “watchful waiting.”

During active surveillance, your doctor will not prescribe treatment but will carefully monitor your condition or your child’s condition for signs of changes.

They may prescribe one or more treatment if you or your child develop symptoms or complications that are severe or are difficult to tolerate.


It’s usually not possible to fully remove PN with surgery, but a surgeon may debulk a tumor to remove as much of it as possible. This may help reduce symptoms or treat certain complications.

PN often grow back again after surgery and may require additional treatment.

Targeted therapy

If NF1-PN can’t be treated with surgery, a doctor may prescribe selumetinib (Koselugo). This oral medication is a type of targeted therapy called a MEK inhibitor that may help shrink NF1-PN and reduce symptoms.

The Food and Drug Administration has approved Koselugo for children age 2 years and older who have NF1-PN that’s causing symptoms and can’t be treated with surgery.

A doctor may also prescribe this treatment off-label to adults.

“Although it’s only approved in kids, we use this targeted therapy and other drugs in the same class off-label to treat the same tumor type in adults,” said Jordan.

Researchers are also conducting clinical trials to study other targeted therapies that might be approved in the future. You can talk with your doctor or visit to learn more about these trials.

Other treatments and support

Your doctor may prescribe other treatments to help manage symptoms or complications of NF1-PN. They may also refer you or your child to another health specialist for support.

For example, they may:

  • prescribe pain medication to help manage pain
  • refer you to an occupational or physical therapist to manage mobility challenges
  • refer you to a speech therapist to manage difficulties with speech or swallowing
  • refer you to a mental health specialist to treat mental health symptoms

You or your child might also find it helpful to take part in a support group or other program for people affected by NF1. Patient advocacy organizations such as the Children’s Tumor Foundation and Neurofibromatosis Network offer a variety of programs and resources to support people with NF1 and their families.

Tumor screening or surveillance

Your doctor may recommend certain screening tests or exams to monitor for signs of other tumors that can develop in people with NF1, including noncancerous and cancerous tumors.

For example, they may encourage you or your child to attend regular check-ups with an eye specialist to look for signs of optic gliomas. These are tumors that grow on the nerve connecting the eye to the brain.

Women with NF1 may also benefit from starting breast cancer screenings at a younger age than usual.

Sometimes NF1-PN can change into the cancer MPNST.

“The most common presenting signs and symptoms of MPNST would be a tumor that begins to grow rapidly, begins to change texture, or becomes newly or differently painful, or if you develop new neurologic deficits, like new weakness or numbness, ” said Jordan.

Let your doctor know if you notice any of these changes.

According to the National Institute of Neurological Disorders and Stroke, most people with NF1 have an average life expectancy.

It’s possible to live a long life with NF1-PN, although it can cause potentially severe complications.

Your outlook will depend on whether you develop severe complications or other types of tumors.

Sometimes NF1-PN may change into the cancer MPNST, which is “the leading cause of NF1-associated mortality,” says Jordan. Roughly 8% to 13% of people with NF1 develop MPNST at some point in their lifetime.

MPNST is an aggressive form of cancer that can quickly spread to other tissues and organs. Roughly 23% to 69% of people with MPNST live for at least five years after getting the diagnosis.

Talk with your doctor to learn more about your specific condition and outlook.

NF1-PN can potentially change into MPNST, which is an aggressive form of cancer.

NF1-PN can also cause complications, such as:

  • atypical bone growth
  • difficulties with breathing, swallowing, or eating
  • hearing or vision changes
  • bladder or bowel problems
  • bleeding

NF1 also raises your risk of other types of noncancerous and cancerous tumors, such as:

  • cutaneous and subcutaneous neurofibromas
  • optic gliomas and other types of gliomas, which are brain tumors
  • gastrointestinal stromal tumors (GIST), which develop in the small intestine
  • pheochromocytomas, which develop on the adrenal gland
  • breast cancer

NF1 can also contribute to other health challenges, such as:

  • atypical bone development, including:
    • unusually curved spine (scoliosis)
    • bowed legs (pseudoarthrosis)
  • cardiovascular conditions, such as:
    • narrowed arteries to the kidneys (renal artery stenosis)
    • high blood pressure (hypertension)
    • certain types of stroke
  • developmental challenges, such as:
    • learning disabilities
    • speech disorders
    • attention deficits
    • hyperactivity
  • seizures
  • headache

The challenges associated with living with and managing NF1-PN may also negatively affect mental health.

People with the genetic condition NF1 have an increased risk of developing plexiform neurofibromas (PN), which are tumors that grow along nerve sheaths. They are usually noncancerous but sometimes develop into cancer.

Your doctor may recommend active surveillance to monitor NF1-PN if the tumor is only causing mild symptoms or no noticeable symptoms.

They may recommend surgery, medication, or other treatment if the tumor is causing symptoms or complications that are severe or hard to tolerate.

NF1 also raises the risk of other types of tumors, including noncancerous and cancerous tumors. It can also cause other physical and mental health challenges.

Talk with a doctor to learn more about treatment options and the outlook for you or for your child with NF1-PN.