Schwannoma

January 22, 2026

This page was reviewed under our medical and editorial policy by Lee Cranmer, M.D., Ph.D., professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte.

Schwannoma is a rare type of tumor that develops in the body’s nervous system. It begins in the body’s Schwann cells, which form part of the nerve sheath – a layer of tissue that covers the nerves in the brain, spinal cord and other parts of the body. Schwannoma tumors are usually benign, meaning they are not cancer, but some may become cancerous over time.

When schwannomas become cancerous, they have the ability to spread to other parts of the body, for example, through the blood. When they become cancerous, they are referred to as malignant peripheral nerve sheath tumors.

What Is Schwannoma?

Schwannoma is the term for any benign or cancerous tumor that begins in the body’s Schwann cells. The Schwann cells form a protective lining around the brain and spinal cord nerves, as well as the peripheral nerves. This lining is called the nerve sheath.

The most common type of schwannoma is vestibular schwannoma, also referred to as acoustic neuroma. Vestibular schwannoma is considered a type of brain tumor, since it develops around the nerves that connect the inner ear to the brain. Most often, vestibular schwannomas are benign and may or may not require treatment. They are often treated surgically.

Other schwannomas may affect the body’s connective tissues, for example, the muscles, fat, tendons or bones. They may be benign, meaning they are not able to move to distant parts of the body (metastasize), or they may be malignant, meaning they are a form of cancer that may move to distant parts of the body. This page focuses on schwannomas in the latter category, rather than vestibular schwannomas.

Schwannoma Symptoms

Some people with sarcoma schwannoma have no symptoms at all. Others may experience signs and symptoms including:

• A lump or bump under the skin
• Aches or sharp pains
• Numbness, tingling or weakness in certain parts of the body
• Burning sensations

What Causes a Schwannoma Tumor?

Doctors and researchers do not yet know the exact causes of schwannoma. However, the condition is slightly more common among people who have certain rare kinds of genetic disorders, including neurofibromatosis, schwannomatosis and Carney complex. When someone is diagnosed with a schwannoma, consideration of one of these genetic conditions is worthwhile, and the care team may refer the patient for evaluation by a genetic specialist. That being said, schwannomas may occur sporadically without any evident cause.

Diagnosis and Testing

In most cases, people only undergo testing for schwannoma if they begin to experience symptoms of the condition. Doctors may use a variety of tests to help diagnose schwannoma. These include:

• A physical examination
• Imaging tests, such as computed tomography, magnetic resonance imaging or ultrasound, which may help determine a tumor’s location and size
• A tumor biopsy to help confirm whether a mass is a schwannoma tumor and whether it is benign or cancerous

Who Treats Schwannomas?

Patients diagnosed with sarcoma-type schwannomas may receive care from a multidisciplinary team of cancer care providers, which may include:

• Medical oncologists, who specialize in treating sarcomas with a variety of treatment options, including medications and other therapies.
• Surgeons, such as surgical oncologists, and other surgical specialists may be involved in the care of patients with schwannomas. This is often determined by the location on the body of the tumor. For example, a neurosurgeon might be requested to evaluate a patient with a schwannoma involving the central nervous system.
• Pathologists, who evaluate schwannoma tissue samples in order to help guide treatment.
• Radiation oncologists, who are experts in using radiation therapy techniques to target and destroy schwannomas.
• Supportive care providers, who help patients manage their physical and mental well-being before, during and after treatment.

Schwannoma Treatment

Treatment for schwannoma may vary depending on a number of factors, including where the tumor is located and what size it is, whether it is benign or malignant and whether it is causing any symptoms. Some common treatments for schwannoma are:

• Surgery to remove a tumor, if it’s growing in size or causing problems with a patient’s health or function.
• Radiation therapy, which may be before surgery to shrink a tumor or afterward to kill any remaining cancer cells.
• Watchful waiting, or observation, which involves regular checkups to monitor a tumor’s behavior. This approach may be taken if a schwannoma tumor is small, is not growing and is not causing any health issues or symptoms.

If a patient has a malignant schwannoma or malignant peripheral nerve sheath tumor, a medical oncologist may provide treatment with chemotherapy. In addition, new therapies are being developed, called targeted therapies, which seek to turn off the signal that causes schwannomas to grow. For that reason, schwannoma patients may see medical oncologists more frequently in future, even if they do not have a malignant schwannoma.