You may not have given much thought to your thymus gland before being diagnosed with myasthenia gravis (MG). However, thymus gland problems are common in people with this autoimmune disorder. Learning more about the link between your thymus gland and MG can help you understand why thymectomy (surgical removal of the thymus) is a treatment option for some people with MG.

In this article, we’ll discuss seven things to know about your thymus gland and MG.

1. The Thymus Is Part of Your Immune System

The thymus gland is a small organ in the upper chest, behind the sternum (breastbone). Its main function is to help train new white blood cells (WBCs) before they enter your bloodstream.

WBCs are made in your bone marrow and then travel to your thymus. In the thymus, new WBCs mature into T cells. T cells are a type of WBC that helps fight infection and protect you from dangerous cells in your body, such as cancer cells. Your thymus gland helps T cells learn how to tell apart your own healthy cells from harmful ones. This helps prevent your immune system from attacking your own tissues instead of only germs, such as bacteria or viruses. After the T cells mature in your thymus gland, they travel to your lymph nodes, where they help your immune system fight infection.

Additionally, the thymus gland produces hormones that help regulate your immune system.

2. Thymus Problems Are Linked to Myasthenia Gravis

Research shows there is a link between abnormalities with the thymus gland and MG. However, researchers don’t fully understand how the thymus gland contributes to MG in some people.

Some thymus gland problems involve cancer, and some don’t. Both types are linked to MG. Between 50 percent and 70 percent of people with MG have thymic hyperplasia, which is inflammation of the thymus gland.

Additionally, between 30 percent and 65 percent of people with a slow-growing type of thymic cancer called thymoma also have MG. While it’s common for people with thymomas to have MG, it’s less common for people with MG to have thymoma. About 10 percent of people with MG are found to also have a thymic tumor.

The reason thymus gland problems are linked to MG is still not fully understood. The link likely exists because MG is an autoimmune disease, a condition in which your immune system attacks your own healthy tissue. In people with MG, the immune system attacks proteins in the neuromuscular junction — the space where your nerves meet your muscles.

Your thymus gland helps T cells learn how to tell the difference between your own cells and foreign ones. Thymus gland abnormalities can lead to autoimmune conditions like MG.

3. Imaging Tests Check for Abnormalities

Doctors often recommend testing the thymus gland for abnormalities in people newly diagnosed with MG. Imaging tests provide a clear picture of your thymus gland to check for problems. The most common imaging test used is a computed tomography (CT) scan. A CT scan uses computer technology and X-rays to create detailed images of your thymus gland and the surrounding tissues. Magnetic resonance imaging (MRI) is also used and provides better detection of tumors, cysts, and other abnormalities of the thymus.

Talk to your health care provider to see if you need to be tested for thymic abnormalities.

4. Removing the Thymus Gland May Help With MG Weakness

Surgical removal of the thymus gland — known as a thymectomy— is a treatment option that may improve weakness in people with MG. Research shows that a thymectomy may reduce the need for medication to treat MG. After thymectomy, some people even achieve permanent remission, where all symptoms of myasthenia gravis disappear without medication.

Thymectomy is just one treatment option for MG. Your health care team can guide you through all your treatment options.

5. Thymectomy Is Recommended for Some People With MG

Your health care team may recommend a thymectomy if you’re under 60 and have moderate to severe muscle weakness from MG. A thymectomy may also help if you have mild muscle weakness that affects the muscles that control breathing or swallowing.

However, a thymectomy may not be right for you if you have:

• Mild MG symptoms
• Ocular MG (muscle weakness that affects only the eye muscles)
• Certain antibodies (immune proteins) related to MG
• MG symptoms that start after age 60

A thymectomy is generally recommended for everyone who has a thymoma or other thymic tumors, no matter how severe their muscle weakness is.

To have a thymectomy, your health care team must feel that your disease is stable enough for you to undergo surgery. In rare cases, the stress of surgery can cause a myasthenic crisis — a serious complication of MG that can cause life-threatening breathing problems.

6. It May Take Years To See the Benefits of a Thymectomy

A thymectomy can improve MG symptoms, but it may take years to see the full effects. After the procedure, most people will continue taking the same medications they used before. However, your doctor may adjust the doses and types of medications over time.

Most people begin to improve within the first year after a thymectomy. From 20 percent to 40 percent of people may experience remission after a thymectomy. Thymectomy procedures that remove more of the thymus gland may have a higher chance of remission, with 40 percent to 60 percent of people achieving remission within five years.

Potential benefits of a thymectomy include:

• Less muscle weakness from MG
• Reduced doses of corticosteroid medications, like prednisone (sold as Deltasone and other brand names)
• Fewer MG medications needed
• Lower doses of MG medications
• Fewer hospital stays for MG complications

It’s important to know that everyone responds to MG treatment differently, and your results may vary. Talk to your health care provider about the potential benefits and risks of a thymectomy.

7. Adults Don’t Need Their Thymus Gland

Your thymus gland plays an important part in helping train T cells. However, this function mostly takes place during childhood. Once you reach adulthood, your thymus gland function isn’t as important. In fact, your thymus gland begins to shrink when you go through puberty. Because your thymus gland isn’t as important as an adult, removing it won’t affect your body’s immune system.

A 2023 study found a possible link between getting a thymectomy and an increased risk of death and cancer. However, more research is needed to find out if this association is caused by the thymectomy or another reason.

Other risks associated with thymectomy are related to the surgery itself, such as:

• Excessive bleeding
• Infection
• Lung problems such as pneumonia or collapsed lung
• Buildup of lymphatic fluid or blood between your lungs and your chest wall
• Myasthenic crisis
• Need for prolonged mechanical ventilation (respirator)

Talk to your health care team about the potential risks and benefits of a thymectomy.

Find Your Team

MGteam is the social network for people living with myasthenia gravis and their loved ones. On MGteam, thousands of members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Have you discussed thymectomy with your MG specialist? If you’ve had a thymectomy, did your MG symptoms improve? Share your experience in the comments below, or start a conversation by posting on your Activities page.