10 Common Causes of Schwannoma

2. Schwannomatosis

Schwannomatosis is a genetic condition that can lead to multiple schwannomas in your body. These tumors grow on nerves and are usually not cancer, and unlike some other nerve disorders, this condition rarely affects the hearing nerve. The main symptom is long-lasting pain, which can affect almost any part of your body and range from mild to severe, sometimes even without a large tumor present.

Other symptoms depend on where the tumors grow, such as numbness, tingling, weakness, or headaches when a tumor presses on a nearby nerve. Changes in certain genes, such as SMARCB1 or LZTR1, can increase your risk by disrupting normal cell growth.

Most cases happen without a family history, but about 15 to 25 percent of cases run in families. Inheriting one changed gene from one parent raises your risk of developing multiple schwannomas. Many people with a single schwannoma do not have this condition, but having several tumors raises concern about it.

3. Hereditary Factors

Some schwannomas develop because of inherited genetic conditions. If you inherit certain gene changes from a parent, your risk of growing nerve sheath tumors increases. One main inherited cause is Neurofibromatosis type 2 (NF2), which leads to noncancerous tumors on nerves. These tumors are especially linked to hearing and balance and often develop on both sides of your head by early adulthood.

NF2 happens when you inherit a changed NF2 gene from one parent, which disrupts normal cell growth and allows tumors to form. Another inherited condition linked to schwannomas is schwannomatosis, which causes multiple schwannomas on different nerves and usually does not affect the hearing nerves. If one of your parents has one of these conditions, you have a higher chance of inheriting it, though sometimes the gene change starts with you.

4. Spontaneous Mutation

A spontaneous mutation is a genetic change that happens by chance, either present at birth or developing in certain cells during your life. It does not come from your parents and often has no clear cause. Schwannomas can form when a random change affects genes that control cell growth, which allows nerve cells to grow out of control and form a tumor.

In many people with a single schwannoma, doctors cannot find a family history of the condition, which suggests a new mutation occurred in the nerve cells. These changes may affect genes linked to nerve sheath growth, leading to tumor development over time.

You cannot predict or prevent most spontaneous mutations, which can happen during normal cell division as small errors build up and allow a schwannoma to grow. Schwannomas that arise this way are usually benign, grow slowly, and rarely spread to other parts of the body.

5. Skeletal Problems

Skeletal problems can contribute to schwannoma development in some people. Your bones and joints protect and support the nerves throughout your body, but structural changes in your skeleton can affect nearby nerves. Some genetic bone conditions increase your risk of nerve sheath tumors by causing abnormal bone growth, uneven limb length, or spine changes.

These changes may press on or irritate nerves over time and promote abnormal Schwann cell growth. Symptoms such as back pain, limb weakness, or numbness may appear if bone changes affect spinal or peripheral nerves. In some cases, spinal deformities narrow the spaces where nerves exit the spine, placing pressure on nerve tissue.

Common skeletal issues linked to nerve problems include spinal curvature changes, bone overgrowth, congenital bone disorders, and chromosomal conditions that affect bone structure. Not all skeletal problems lead to schwannomas, but if you have a known bone disorder along with nerve pain or lumps under the skin, your doctor may check for nerve sheath tumors.

6. Carney Complex

Carney complex is a rare genetic disorder that raises your risk of developing several types of tumors, which affect your skin, heart, hormone glands, and nerves. If you have this condition, a gene change that controls cell growth allows certain cells to grow and divide more than they should, which leads to different tumors over time. About 10 percent of people with Carney complex develop a rare nerve tumor called psammomatous melanotic schwannoma. It starts in Schwann cells that wrap around and protect your nerves.

You may also notice dark spots on your skin, especially around your lips or eyes, small lumps under your skin, heart tumors called myxomas, and hormone problems that affect your weight, growth, or energy levels. Carney complex often runs in families, and inheriting one changed gene from a parent can cause it, though the gene change sometimes happens for the first time in you.

7. Diabetes

Diabetes is a long-term condition that causes high blood sugar levels, which can damage nerves throughout your body over time, known as diabetic neuropathy. While nerve damage does not directly cause schwannomas, long-term nerve irritation and injury may change how nerve cells and the surrounding Schwann cells behave.

Ongoing stress from high blood sugar may cause these cells to react abnormally and create an environment where abnormal growth, including nerve sheath tumors, could develop. This same nerve damage can also cause everyday symptoms. Common nerve-related effects of diabetes include numbness in your hands or feet, tingling or burning pain, muscle weakness, and reduced sensation.

You can lower nerve damage risk by managing your blood sugar with lifestyle changes and medications. Stable blood sugar helps protect your nerves and may reduce long-term complications that affect nerve health.

8. Cancer

Cancer rarely causes a schwannoma, but it can play a role in some nerve sheath tumors. Most schwannomas are benign and do not spread to other parts of your body, but in very uncommon cases, a tumor in the nerve lining can become malignant, known as a malignant peripheral nerve sheath tumor.

If you have a history of cancer or prior radiation treatment, your risk of new nerve tumors may increase, as radiation can damage DNA and lead to abnormal cell growth in the nerve sheath. Previous chemotherapy exposure and repeated radiation to the same area further increase long-term cellular instability within nerve tissue.

Warning signs of a malignant tumor include rapid growth, severe or worsening pain, weakness in a nearby limb, and changes in sensation. If your tumor shows unusual features under a microscope, your care team may order more imaging tests to guide treatment and lower the risk of spread.

9. Advanced Age

As you grow older, your risk of many tumors increases, including schwannomas. These tumors often appear in adults rather than children, with many cases found in people over age 30 and becoming more common in middle age and later years. Over time, small changes can build up in the genes that control cell growth, and when these changes affect Schwann cells, they may grow into a tumor.

Age also allows more time for random genetic errors to occur, and most schwannomas are not inherited but develop by chance after years of normal cell activity. Certain types, such as vestibular schwannomas, often appear in adults between ages 30 and 60, and you may not notice symptoms right away because these tumors usually grow slowly. Advanced age raises the likelihood of schwannoma because of the natural changes that happen in your cells over time.

10. Radiation Exposure

Radiation exposure increases your risk of developing a schwannoma. Schwannomas grow from Schwann cells, which form the protective covering around your nerves. When radiation damages the DNA inside these cells, it can change how they grow and divide. High doses of radiation pose the greatest risk. A large dose given over a short time can injure healthy tissue and increase the chance of tumors forming later.

Lower doses spread out over time tend to cause less harm, but repeated exposure can still affect your cells. Radiation can reach your body in different ways. Certain medical treatments use radiation to treat cancer. Accidents, environmental exposure, or past radiation therapy to the head, neck, or spine can also affect nearby nerves.

Your age at the time of exposure matters. Children and young adults face higher risk because their cells divide more quickly, and they have more years ahead for a tumor to develop. Damage to only one part of your body is usually less harmful than exposure to your whole body, but nerves in the treated area can still be affected.