What Are Plexiform Neurofibromas?

Reviewed on 11/19/2021

Plexiform neurofibromas are a type of benign tumor, which means they are usually not cancerous, although sometimes they can grow and turn into cancer. Plexiform neurofibromas are believed to be present at birth.
Plexiform neurofibromas are a type of benign tumor, which means they are usually not cancerous, although sometimes they can grow and turn into cancer. Plexiform neurofibromas are believed to be present at birth.

Plexiform neurofibromas are a type of benign tumor that grows along nerves, commonly seen in people who have neurofibromatosis type I (NF1). Neurofibromatosis is a rare genetic disorder that typically causes benign (noncancerous) nerve tumors and growths in other parts of the body, including the skin. 

  • Plexiform neurofibromas are usually not cancerous, but some may develop into cancer.
  • Plexiform neurofibromas are believed to be present at birth and usually grow intermittently during childhood. Plexiform neurofibromas may be small or can involve larger areas of the body and can occur on the face, neck, arms, legs, back, chest, abdomen, and internal organs.
  • Large tumors can result in thick and misshapen nerves, which can affect the structure of nearby bone, skin, and muscle. They may feel like a bunch of cords or knots under the skin and can vary in texture or have a darker pigmentation on top of the skin. 

Symptoms of plexiform neurofibromas include: 

What Causes Plexiform Neurofibromas?

  • Most plexiform neurofibromas are symptoms of a rare genetic disorder called neurofibromatosis. Neurofibromatosis is caused by genetic mutations of certain genes believed to function as tumor suppressors. 
  • Some people inherit the mutated gene from a parent, and in other people, the mutation occurs for unknown reasons (spontaneous mutation).

How Are Plexiform Neurofibromas Diagnosed?

Patients who have neurofibromatosis are routinely screened for the development of tumors such as plexiform neurofibromas. They can often be diagnosed with a physical examination. 

Magnetic resonance imaging (MRI) scans can allow for complete imaging of the growths.

What Is the Treatment for Plexiform Neurofibromas?

  • Surgery is often the primary treatment option for plexiform neurofibromas, but these tumors can be difficult to remove surgically because they are intertwined with normal tissue. 
  • When it is not possible to remove all of a plexiform neurofibroma, a debulking procedure that removes a portion of the tumor may be performed. However, plexiform neurofibromas can grow back after surgery.
  • Newer medications are being developed to treat plexiform neurofibromas, called MEK inhibitors, that can reduce the size of plexiform neurofibromas in many people with NF1. The MEK inhibitor selumetinib (Koselugo) was approved by the Food and Drug Administration (FDA) to treat symptomatic plexiform neurofibromas in children with NF1 and may be an option for some individuals who cannot have surgery. 

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What Are Complications of Plexiform Neurofibromas?

Plexiform neurofibromas may not cause any symptoms in themselves, but because they may be located on or near major organs, they can cause complications. 

Complications of plexiform neurofibromas may include: 

  • Mast cells within plexiform neurofibromas can cause itching
  • Depending on their size and location, some plexiform neurofibromas cause disfigurement which may change a person’s appearance
  • They can press on important organs 
    • If they press on the airways or gastrointestinal tract, they can cause dysfunction
    • If they involve the peripheral nerves or spinal cord, they can cause pain, weakness, numbness, tingling, or bowel/bladder problems
  • Plexiform neurofibromas may be slightly painful when bumped or pushed, though they usually do not cause severe pain
    • Seek medical care right away if you have been diagnosed with a plexiform neurofibroma and you experience severe pain
  • Although plexiform neurofibromas are not cancerous (benign), they are at increased risk of becoming cancerous (malignant)
    • Cancerous plexiform neurofibromas are called malignant peripheral nerve sheath tumors (MPNSTs)
    • Treatment for MPNSTs may include one or more of the following: surgery, radiation, chemotherapy 

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Reviewed on 11/19/2021
References
Image Source: iStock Images

https://www.ctf.org/images/uploads/documents/Plexiform_Neurofibromas_NF1.pdf

https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Neurofibromatosis