Benign Peripheral Nerve Tumors – Symptoms and Causes
Understanding Peripheral Nerve Growths
Benign peripheral nerve growths are non-cancerous tumors that develop on the nerves outside the brain and spinal cord. These growths may occur within the nerve itself or in surrounding tissue.
Though typically slow-growing and non-spreading, they can interfere with nerve signaling and impact physical function.
Peripheral nerve tumors vary in size, appearance, and behavior. While most are isolated and harmless, some are associated with genetic conditions that may lead to multiple growths or more serious complications.
Signs and Warning Signals
Benign peripheral nerve tumors can cause different symptoms based on where they grow and which nerves they affect. You might notice:
- A visible lump or swelling under the skin
- Pain, tingling sensations, or numbness
- Muscle weakness or functional loss in the affected area
- Balance problems or dizziness
These symptoms happen when the tumor puts pressure on the nerve where it’s growing. The tumor can also press against nearby nerves, blood vessels, or tissues, causing additional problems.
While larger tumors may cause more noticeable symptoms, even small tumors can create significant discomfort. The severity of symptoms doesn’t always directly relate to the tumor’s size.
Causes
The exact reason for benign nerve tumors often remains unknown. In some cases, these growths may be inherited from family members through genetics.
Peripheral nerve growths form on nerves that connect the brain and spinal cord to other body parts. These growths can develop inside nerves (intraneural) or press against them from outside (extraneural).
Most are non-cancerous, but they can still cause significant problems by disrupting normal nerve function. The main types include:
Neurofibroma
- Develops from multiple cell types within the nerve sheath
- Often appears as soft, flesh-colored bumps
- May involve several nerve bundles
- Common in people with neurofibromatosis type 1 (NF1)
Schwannoma
- Arises from Schwann cells that surround nerve fibers
- Usually affects a single nerve bundle
- Grows slowly and often remains unnoticed for years
- May form irregular shapes in the spine, pelvis, or limbs
- Vestibular schwannoma (acoustic neuroma) forms near the brainstem and may affect hearing or balance
- Multiple schwannomas may occur in individuals with schwannomatosis
Perineurioma
- Rare tumor derived from the perineurial cell layer
- Occurs in two forms:
- Intraneural (within the nerve) more common in young individuals, can cause progressive weakness
- Extraneural (in surrounding soft tissue)
Lipoma
- Made up of fat cells
- Appears under the skin, usually on the neck, shoulders, arms, or back
- Rarely painful unless pressing on nearby nerves
Ganglion Cyst
- Fluid-filled lump commonly near joints, especially the wrists
- Sometimes linked to prior injuries
- Can press on nerves and interfere with movement
- Often resolves on its own but may require treatment if symptomatic
Risk Factors
Different types of benign peripheral nerve tumors have specific risk factors:
- Neurofibromatosis Type 1 (NF1): This genetic condition increases the risk of developing neurofibromas. Most people with neurofibromas don’t have NF1, but those who do often develop multiple tumors.
- Malignant Transformation: People with NF1 face a higher risk of developing malignant peripheral nerve sheath tumors.
- Schwannomatosis Gene: Having this specific gene raises the risk of developing schwannomas.
These risk factors relate to underlying genetic conditions that affect nerve tissue growth.
