Anatomic illustration of a peripheral nerve tumor

Peripheral Nerve Tumors

Specialized surgical care for tumors that arise from nerves outside the brain and spinal cord, with a focus on preserving nerve function.

Overview

What Are Peripheral Nerve Tumors?

Peripheral nerve tumors are tumors that grow from the nerves running throughout the body, outside of the brain and spinal cord. Most are benign and slow-growing, with the two most common types being schwannomas and neurofibromas. A small number are malignant and require a more involved approach.

Common symptoms include a new lump along a nerve, tingling or electric shock sensations when the lump is pressed, persistent pain in a specific area, and numbness, tingling, or weakness in the part of the body served by the affected nerve. A mass that is rapidly growing or suddenly changing should be evaluated promptly.

Treatment for benign tumors is usually surgery aimed at removing the tumor while preserving the function of the nerve, and small tumors that aren’t causing symptoms can sometimes be safely watched. Treatment for malignant tumors typically combines surgery, radiation, and sometimes chemotherapy. Dr. Sherman has experience treating peripheral nerve tumors at Rutgers Cancer Institute in New Brunswick, NJ.

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The information on this page is general educational information and is not medical advice. It does not create a doctor-patient relationship or reflect a treatment recommendation for any individual. Treatment decisions require an individual evaluation by a qualified physician.

Peripheral nerve tumor symptoms depend on which nerve is involved and what that nerve controls. Some tumors cause obvious symptoms early; others grow quietly for years before being discovered.

Here’s what makes symptoms worth investigating.

A new lump along a nerve. A painless or slightly tender lump that can be felt along the path of a nerve is one of the most common presentations of a benign peripheral nerve tumor. The lump may be firm and well-defined, and it may or may not cause tingling when pressed.

Tingling or electric shock sensations when pressing on a lump. Tapping or pressing on a nerve tumor often produces a tingling or shock-like sensation that travels along the path of the affected nerve. This is a classic sign of a mass involving a nerve and warrants evaluation.

Persistent pain in a specific area. Pain that is localized, burning, or radiating along a specific nerve distribution can indicate a peripheral nerve tumor. Pain that is worse at night or that wakes the patient from sleep is particularly worth evaluating.

Numbness, tingling, or weakness in the area served by a nerve. Peripheral nerve tumors can interfere with the signals the nerve is supposed to carry, causing numbness, tingling, or weakness in the muscles or skin areas the nerve supplies. Progressive symptoms like these warrant imaging.

A mass that is rapidly growing or changing. Most benign nerve tumors grow very slowly over months to years. A mass that is rapidly enlarging, suddenly becoming painful, or changing in character is concerning for malignant transformation and warrants prompt evaluation, particularly in patients with NF1.

New or worsening symptoms in a known nerve tumor or plexiform neurofibroma. For patients with known benign nerve tumors or NF1, any new pain, rapid growth, or new neurologic symptoms in or near a preexisting tumor should be reported to a doctor promptly. These can be early signs of malignant transformation.

Symptoms in NF1 patients. Patients with NF1 are monitored over their lifetime for new neurofibromas and for any signs of MPNST. New pain, rapid growth, hardening of a previously soft tumor, or new neurologic deficits associated with a known plexiform neurofibroma should prompt immediate evaluation.

When to treat it as an emergency. Sudden severe pain associated with a known nerve tumor, rapidly progressive weakness, or new signs of major neurologic compromise warrant prompt evaluation. Most peripheral nerve tumor symptoms are not emergencies in the hours-to-minutes sense, but rapid changes in a known mass should be evaluated without delay.

For most peripheral nerve tumor symptoms, the pace of evaluation is measured in weeks. Benign tumors are slow-growing, and there is usually time for imaging, consultation, and thoughtful decision-making. For suspected malignant tumors or for rapidly changing symptoms, the workup moves faster.

Imaging

MRI is the standard imaging study for peripheral nerve tumors. It provides detailed information about the tumor’s size, location, shape, and its relationship to surrounding nerves, blood vessels, and other structures. Features visible on MRI can often suggest whether a tumor is more likely to be benign or malignant, though imaging alone cannot provide a definitive diagnosis.

For larger tumors, tumors suspected of being malignant, or tumors in complex locations, a CT scan may be added to provide additional detail about the bones and surrounding tissue. For patients being evaluated for MPNST, PET imaging is sometimes used to help distinguish benign from malignant lesions and to evaluate for spread to other parts of the body.

For patients with NF1, periodic whole-body MRI may be used to monitor existing tumors and identify new ones, particularly when there is clinical concern about possible malignant transformation.

Tissue Diagnosis

For benign peripheral nerve tumors with a typical appearance on imaging, a preoperative biopsy is often not needed. Schwannomas in particular have a characteristic imaging appearance, and in many cases the diagnosis is confirmed from the tissue removed during the surgical procedure rather than from a separate biopsy beforehand. Avoiding unnecessary biopsies helps protect nerve function, because any procedure that involves a nerve carries some risk.

For tumors that look atypical on imaging, for tumors that are rapidly growing, or for any tumor suspicious for MPNST, a biopsy is typically performed before surgery. Biopsies of suspected malignant nerve tumors are usually done as image-guided needle biopsies. Getting the tissue diagnosis before surgery is especially important for MPNST because the surgical approach for a sarcoma is different from the approach for a benign tumor.

Genetic Evaluation

For patients with multiple peripheral nerve tumors, a large plexiform neurofibroma, or a family history of nerve tumors, genetic evaluation for NF1, NF2, or schwannomatosis may be recommended. Identifying an underlying genetic condition affects long-term monitoring, treatment planning, and guidance for family members.

Peripheral nerve tumor treatment depends on whether the tumor is benign or malignant, which nerve is involved, the tumor’s size and location, and whether the patient has an underlying genetic condition. For most benign tumors, surgery is the only treatment needed. For MPNST, treatment typically combines multiple modalities.

Surgery for Benign Tumors

Surgery is the primary treatment for symptomatic or growing benign peripheral nerve tumors. The goal is complete removal of the tumor while preserving the function of the affected nerve. For schwannomas, this is usually achievable because of the tumor’s structure, in which the tumor can be separated from the surrounding nerve fibers through a careful technique called intracapsular dissection. The surgeon opens the tumor’s outer capsule, removes the tumor from within, and leaves the functional nerve fibers intact.

For neurofibromas, complete removal is more challenging because the tumor grows within and around the nerve fibers themselves. In some cases, part of the nerve must be removed along with the tumor, and the decision to operate weighs the benefits of tumor removal against the possible loss of nerve function. For plexiform neurofibromas, surgical removal is often difficult because of the tumor’s extensive involvement of multiple nerve branches, and surgery is typically reserved for tumors causing significant symptoms or suspicious changes.

Intraoperative nerve stimulation is a standard part of peripheral nerve tumor surgery in experienced hands. It allows the surgical team to identify functional nerve fibers during the operation and to preserve them while removing the tumor. This is one of the main techniques that makes nerve-sparing surgery possible.

Observation for Small or Asymptomatic Benign Tumors

Not every benign peripheral nerve tumor requires surgery. Small tumors that are causing no symptoms may be safely monitored with periodic imaging, particularly when surgical removal would carry a meaningful risk to nerve function. Observation is a reasonable approach for many small schwannomas and stable neurofibromas, with the plan shifting to surgery if the tumor grows, causes new symptoms, or shows any worrisome changes.

Treatment for MPNST

MPNST requires a fundamentally different approach from benign peripheral nerve tumors. The primary treatment is wide surgical resection, in which the tumor is removed along with a margin of surrounding healthy tissue. Achieving negative margins (no tumor cells at the edge of the removed tissue) is the strongest predictor of long-term outcomes. For MPNSTs in the limbs, limb-sparing surgery is the goal whenever possible, though in some cases amputation may be necessary if complete removal cannot otherwise be achieved.

Radiation therapy is typically added for most MPNSTs, either before or after surgery, to reduce the risk of local recurrence. Chemotherapy is often added for larger tumors, high-grade tumors, or tumors that cannot be completely removed by surgery. The specific sequence of surgery, radiation, and chemotherapy is determined by a multidisciplinary team, because MPNST is treated similarly to other soft tissue sarcomas and benefits from coordination between surgical oncology, radiation oncology, and medical oncology.

Targeted Therapy for NF1-Associated Plexiform Neurofibromas

For patients with NF1 who have symptomatic or inoperable plexiform neurofibromas, a targeted therapy called selumetinib (a MEK inhibitor) has become an important treatment option. Selumetinib interferes with a specific cellular signaling pathway that drives tumor growth in NF1 and can shrink plexiform neurofibromas and improve symptoms. It is not a cure, but it has changed what is possible for patients whose tumors cannot be safely removed by surgery.

Clinical Trials

Clinical trials are an active area in peripheral nerve tumor care, particularly for MPNST and for NF1-related tumors. Research is ongoing into additional MEK inhibitors, combinations of targeted therapies, and newer approaches to MPNST treatment. For patients with these rare tumors, trial enrollment can offer access to treatments that aren’t yet available as standard care.

How the Plan Gets Made

Peripheral nerve tumor treatment involves weighing the benefits of removing the tumor against the potential cost to nerve function, and the right answer is often different for different patients. For benign tumors, the plan is usually made between the patient and a neurosurgeon who has experience with peripheral nerve surgery and can give a clear recommendation about whether, when, and how to operate. For MPNST, the plan involves a multidisciplinary team coordinating surgery, radiation, chemotherapy, and long-term monitoring. For NF1 patients, the plan also includes lifelong surveillance and, in many cases, connection to a comprehensive neurofibromatosis program.

Treatments commonly used for this conditionPeripheral Nerve Tumor Surgery, and Clinical Trial Enrollment.

Technology

Using XR Technology To Advance Medical Care

Dr. Sherman integrates VR and AR visualization into surgical planning and patient education, giving patients a clearer picture of their diagnosis and the approach to treatment.

Common Questions About Peripheral Nerve Tumors

The great majority are not. Most peripheral nerve tumors are benign schwannomas or neurofibromas that grow slowly and do not spread. A small number are malignant peripheral nerve sheath tumors (MPNSTs), which are rare but aggressive cancers. The specific diagnosis is confirmed by examining tissue, either from a biopsy before surgery or from the tumor after it is removed.

For most schwannomas, yes. Schwannomas typically arise from a single fascicle within a nerve, and experienced surgeons can usually separate the tumor from the surrounding nerve fibers and remove it while preserving nerve function. Neurofibromas are more challenging because they grow within the nerve fibers themselves, and complete removal sometimes involves some impact on nerve function. Intraoperative nerve stimulation helps the surgical team identify and protect functional nerve fibers during the operation.

A schwannoma is a benign tumor that arises from Schwann cells, the cells that form the myelin coating around nerves. Schwannomas are the most common type of peripheral nerve tumor in adults and are typically slow-growing, well-defined, and curable with complete surgical removal. Most people with a schwannoma have a single tumor, though patients with hereditary conditions like schwannomatosis or NF2 may have multiple.

Malignant peripheral nerve sheath tumor (MPNST) is a rare soft tissue sarcoma that arises from nerve sheath cells. It is treated with wide surgical removal aimed at achieving negative margins, usually combined with radiation therapy and often chemotherapy. For MPNSTs in the limbs, limb-sparing surgery is the goal whenever possible. MPNST treatment is best managed by a multidisciplinary team with experience in soft tissue sarcomas.

Neurofibromatosis refers to a group of genetic conditions that predispose patients to developing nerve tumors. Neurofibromatosis type 1 (NF1) is the most common and is associated with multiple neurofibromas, plexiform neurofibromas, and an elevated lifetime risk of MPNST (estimated at 8 to 13 percent). Neurofibromatosis type 2 (NF2) and schwannomatosis are distinct conditions associated with multiple schwannomas. Patients with any of these conditions benefit from lifelong monitoring by specialists familiar with the disease.

Surgery is typically recommended when a benign tumor is causing symptoms, growing on serial imaging, or showing any features suspicious for malignant change. For small, asymptomatic tumors, observation with periodic imaging is often reasonable. For MPNST, surgery is almost always recommended as soon as the diagnosis is made, and the planning of surgery is usually integrated with radiation and chemotherapy decisions.

Yes, particularly for complex or unusual nerve tumors, for suspected MPNST, and for patients with NF1 or related conditions. Peripheral nerve surgery is a specialized area, and the balance between complete tumor removal and nerve function preservation depends heavily on surgical experience. A second opinion with a surgeon who treats peripheral nerve tumors regularly can clarify the options and help ensure the best possible outcome.

Next Step

Newly Diagnosed or Seeking a Second Opinion?

Dr. Sherman is accepting new patients at Rutgers Cancer Institute in New Brunswick, New Jersey. Whether you’ve just been diagnosed or you’re looking for another perspective on a treatment plan, a consultation is the first step toward understanding your options.

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