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 myasthenia gravis 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.

The thymus gland is a small organ in the upper chest, behind the 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.

🗳️ Have you discussed the pros and cons of thymectomy (surgery to remove the thymus gland) with your MG specialist?

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

Some thymus gland tumors involve cancer, and some don’t. Both types are linked to MG. Between 50 percent and 70 percent of people with myasthenia gravis have hyperplasia, or abnormal growth of the thymus gland.

Additionally, between 30 percent and 65 percent of people with thymoma, a slow-growing tumor of the thymus, also have an autoimmune disease such as myasthenia gravis. An autoimmune disease is a condition in which your immune system attacks your own healthy tissue.

While it’s common for people with thymomas to have myasthenia gravis, it’s less common for people with MG to have thymoma. Between 10 percent and 20 percent of people with myasthenia gravis also have a thymoma.

Thymus gland problems are linked to myasthenia gravis because MG is an autoimmune disease. In people with myasthenia gravis, the immune system attacks certain proteins in the neuromuscular junction — the space where your nerves communicate with your muscles.

Because your thymus gland helps T cells learn how to tell the difference between your own cells and foreign ones, thymus gland changes can lead to autoimmune conditions like myasthenia gravis.

Doctors often recommend testing the thymus gland for abnormalities in people newly diagnosed with myasthenia gravis. Imaging tests provide a clear picture of your thymus gland to check for problems.

“I began having MG symptoms only a few months before finding out that a tumor on my thymus had grown and would need to be removed.”

— An MGteam member

The most common imaging test doctors use to look at the thymus gland 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.

Doctors may also use magnetic resonance imaging (MRI) to distinguish between certain types of thymus problems or as an additional tool if the CT scan is unclear.

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

Thymectomy is just one treatment option for myasthenia gravis. Your healthcare team can guide you through all your treatment options.

Your healthcare team may recommend a thymectomy as part of your MG treatment plan. A thymectomy may be appropriate for people with a thymoma or other types of thymic tumors.

“I had a thymectomy and felt great after. I even reduced my meds. However, I recently had an ocular flare-up that still isn't totally resolved.”

— An MGteam member

Other factors your team will take into consideration include:

• AChR-antibody status — Thymectomies are considered more beneficial for people who test positive for AChR antibodies.
• Severity of MG symptoms — Thymectomy may be recommended for people with myasthenia gravis at any stage but is more common among people with more severe cases.
• Type of MG — Thymectomy is considered beneficial for generalized myasthenia gravis but may be seen as controversial for ocular myasthenia gravis (MG that affects only the eyes).
• Age — Some surgeons are reluctant to perform thymectomy on people over the age of 60 due to health risks.

For thymectomy, your healthcare team must conclude that your health is stable enough for you to undergo surgery. In rare cases, the stress of surgery can cause a myasthenic crisis — a serious complication of myasthenia gravis that can lead to life-threatening breathing problems.

A thymectomy can improve MG symptoms and reduce how much MG treatment you need. However, it doesn’t work right away. It may take years after a thymectomy to see the full effects.

After the procedure, people may continue taking the same medications they used before. Your doctor may adjust the doses and types of medications over time depending on your symptoms.

Many people begin to improve within the first year after a thymectomy. Less than 20 percent of people who underwent thymectomy achieve remission in the first year. But the remission rate rises to about 50 percent within seven to 10 years after surgery.

“My symptoms are being managed really well now since my thymectomy.”

— An MGteam member

Potential benefits of a thymectomy include:

• Less muscle weakness from MG
• Fewer or lower doses of MG medications, such as prednisone, needed
• Fewer hospital stays for MG complications
• Remission

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

While myasthenia gravis may play a role in your symptoms, other conditions can affect your thymus gland, too. It’s good to be aware of symptoms these conditions may cause.

Thymoma and thymic carcinoma (a cancer of the thymus gland) symptoms can include:

• Persistent cough or hoarse voice
• Trouble breathing or gasping for air
• Pain in the chest and throat region
• Swelling in the upper body, neck, or face

If you experience any of these symptoms, contact your healthcare team so you can get tested for thymoma and thymic carcinoma.

If you have any specific questions about your myasthenia gravis or thyroid treatment plans, it’s always best to consult your medical team for advice.