What is Thyroid Lymphoma?
Thyroid lymphoma is a type of cancer that affects the thyroid gland. It can either be primary or secondary. Primary thyroid lymphoma starts in the thyroid gland first, and later on, can spread to the lymph nodes and other parts of the body. But in secondary thyroid lymphoma, the lymph nodes and other organs are affected first, and later the disease spreads to the thyroid. For this discussion, we’ll mainly focus on primary thyroid lymphomas.
What Causes Thyroid Lymphoma?
Primary thyroid lymphoma is quite rare. It makes up less than 5% of all thyroid cancers and less than 3% of all lymphomas that occur outside the lymph nodes. Usually, this type of lymphoma is seen in people who already have a condition called Hashimoto’s thyroiditis, a chronic, autoimmune condition that affects the thyroid. Research has found a link between this type of thyroiditis and primary thyroid lymphoma.
The risk of developing primary thyroid lymphoma is nearly 60 times higher in people with thyroiditis compared to those without. It generally appears 20 to 30 years after the initial diagnosis of thyroiditis.
Risk Factors and Frequency for Thyroid Lymphoma
Thyroid lymphoma is a rare condition, with only about 2 cases in 1 million people every year. It is more likely to occur in areas where thyroiditis, an inflammation of the thyroid, is more common. It tends to affect women more than men, with a ratio of about 4 to 1. Typically, the diagnosis is made around the age of 65.
Signs and Symptoms of Thyroid Lymphoma
Different types of lymphomas, including DLBCL (a more aggressive type), MALT lymphoma, or follicular lymphomas, can affect how quickly symptoms show up. These symptoms can range from appearing in just a few days to taking several years to develop. However, DLBCL generally has a more aggressive presentation, which means symptoms often appear more quickly.
The main local symptom of thyroid lymphoma is a rapidly growing thyroid gland, also known as a goiter. This growth may cause obstructive symptoms due to the size of the gland pressing on other structures in the neck. These symptoms can include:
- Breathing difficulties, or dyspnea
- Stridor, a high-pitched sound when breathing, caused by tracheal compression
- Difficulty swallowing (dysphagia) due to pressure on the esophagus
- Neck pain
- Swelling in the face caused by compression of neck veins and the superior vena cava
- A hoarse voice due to compression on the recurrent laryngeal nerve
Alongside these local symptoms, people with thyroid lymphoma may also have systemic symptoms, or symptoms affecting the whole body. Common symptoms include the B-symptoms of lymphoma (fever, night sweats, and weight loss) and symptoms of an underactive thyroid, or hypothyroidism. This hypothyroidism could be a result of Hashimoto thyroiditis or because the lymphoma has infiltrated the thyroid gland. The hypothyroid symptoms can include:
- Fatigue
- Inability to tolerate cold
- Constipation
- Dry skin or hair
- Hoarse voice
- Menstrual irregularities
In rare cases, some patients may initially exhibit an overactive thyroid (hyperthyroidism) due to damage to the thyroid follicles by the lymphoma.
During a physical examination, doctors typically find a hard, enlarged thyroid gland that can’t move normally, along with swollen lymph nodes in the neck or above the collarbone. Interestingly, in rare cases, a patient might present with a large distinct nodule instead of a generalized thyroid enlargement.
Testing for Thyroid Lymphoma
If you’re being tested for thyroid lymphoma, here’s what might happen:
Laboratory Tests
There is no specific lab test that can confirm thyroid lymphomas. Often, doctors will run tests to check for signs of low thyroid function, or hypothyroidism, which might include a high level of thyroid-stimulating hormone (TSH) and low levels of T3 and T4 hormones. Signs of Hashimoto’s thyroiditis, an autoimmune condition that can lead to hypothyroidism, can also be common. These might include high levels of antibodies against thyroid proteins.
It’s worth noting that in rare cases, lab results might show high thyroid function, or hyperthyroidism, which is characterized by low TSH and high T3 and T4 levels. If you’re on medication for Hashimoto’s thyroiditis, the lab results might show normal levels of TSH, T3, and T4, meaning that your medication helps keep your thyroid function stable.
Imaging
Your doctor will likely start with an ultrasound of the thyroid. Although this may not show definite signs of lymphoma, it can suggest the possibility if certain patterns are noticed. The ultrasound might show areas that send echoes back more strongly than usual, areas that look like pseudo cysts, or increased blood flow. In one study, nearly half of the patients whose ultrasounds suggested possible lymphoma were confirmed to have the condition.
To check if the disease has spread beyond the thyroid, if the windpipe is involved, or if the lymph nodes are affected, your doctor may opt for a computed tomography (CT) scan or magnetic resonance imaging (MRI). A PET scan, which uses a radioactive drug to highlight areas of concern, might show increased activity throughout the thyroid. Although this doesn’t tell us if it’s lymphoma, it’s useful for staging the disease and measuring the response to treatment.
Biopsy
If thyroid lymphoma is suspected, you’ll probably have a biopsy. This is where a tissue sample is taken and examined to confirm the diagnosis. Usually, doctors start with a fine needle aspiration (FNA), where a small needle is used to draw out cells from the thyroid. However, this only gives a definite diagnosis in 50% to 80% of cases. A core biopsy, where a larger tissue sample is taken, is more sensitive and can show the difference between thyroid inflammation and lymphoma.
In cases where FNA and core biopsy don’t give clear results, doctors may recommend an open surgical biopsy. This procedure provides a larger tissue sample and could help identify the subtype of lymphoma.
Treatment Options for Thyroid Lymphoma
Primary thyroid lymphoma, a rare type of tumor in the thyroid, is treated differently depending on its subtype and severity. The best approach to treat this disease isn’t set in stone, largely because the illness is so uncommon. However, we can apply our knowledge from studies of non-Hodgkin lymphomas, which are similar types of cancers.
For a subtype called DLBCL, which is in its earlier stages (stages IE or IIE), the suggested treatment involves both chemotherapy and radiotherapy. When combined, these methods could potentially provide better success rates for patients over a 5-year period compared to chemotherapy alone. If DLBCL is more advanced (stages IIIE or IV), the treatment combines rituximab, a drug that selectively attacks certain cancer cells, with a range of chemotherapy drugs.
For other subtypes such as MALT lymphoma and follicular lymphoma, early-stage treatment could involve radiotherapy alone or mixed with rituximab-enhanced chemotherapy. If the disease is more advanced, the best treatment could involve rituximab either by itself or combined with other chemotherapy medications.
Surgery isn’t usually recommended for treating primary thyroid lymphoma. This is because potential surgical risks don’t provide extra benefits when compared to radiotherapy and chemotherapy. Symptoms such as breathing difficulties can typically improve soon after starting a specific chemotherapy treatment plan, which helps to avoid the need for surgeries like tracheostomy or thyroid removal.
When hypothyroidism symptoms pop up, maybe as a result of a condition called Hashimoto thyroiditis, the spread of lymphoma throughout the thyroid gland, or lymphoma-related radiation treatment, doctors usually recommend thyroid hormone replacement therapy. One study suggested that, for primary thyroid lymphoma, getting a diagnostic sample of the tumor followed by chemotherapy alone was more effective in achieving full disease remission than surgically reducing the size of the tumor and then using additional treatment methods.
Sometimes, the lymphoma may either be resistant to the initial treatment or may recur shortly after the treatment is completed. This is known as refractory lymphoma. In other cases, the lymphoma may respond to treatment and go into remission but can come back after some time; this is termed relapsed lymphoma. The subsequent treatment options for such cases depend on the subtype of lymphoma and how long it takes for the disease to return after the initial treatment. The decision for these treatments is largely based on findings from non-Hodgkin lymphoma studies and trials.
What else can Thyroid Lymphoma be?
When a doctor is trying to diagnose primary thyroid lymphoma, they need to be aware that other conditions could be causing the symptoms. This condition can cause a rapid growth in the thyroid (a gland in the neck), making the mass in the thyroid hard and not able to move around easily. These symptoms can also be caused by other problems, including:
- Anaplastic thyroid carcinoma, a type of thyroid cancer
- Papillary thyroid carcinoma, another type of thyroid cancer
- Follicular thyroid carcinoma, yet another type of thyroid cancer
- Medullary thyroid carcinoma, one more thyroid cancer type
- Simple colloid goiter and benign thyroid nodules – these are non-cancerous (benign) conditions involving growths or lumps in the thyroid
Even though primary thyroid lymphoma is quite rare, it’s crucial to consider it as a possible diagnosis when a rapidly growing thyroid nodule or goiter is found. Timely diagnosis and appropriate treatment is key to better health outcomes.
What to expect with Thyroid Lymphoma
The chances of recovering from primary thyroid lymphoma, a type of cancer that starts in the thyroid gland, depend on a variety of factors. These include the type and stage of the cancer, the patient’s age, health status, and the treatment regime suggested by the healthcare provider.
Data collected by a body called the Surveillance Epidemiology and End Result (SEER) indicates the percentage of people who remain disease-free for five years after treatment. For different types of thyroid lymphoma, this varies from as high as 96% for MALT lymphoma to 75% for a kind named DLBCL.
Another study from UK lymphoma treatment centers reported various five-year survival rates. On average, across several types of thyroid lymphomas, about half of patients survived for five years or longer after diagnosis and treatment. The rate differs depending on the type of lymphoma, with as much as 75% for indolent B-cell lymphoma and as low as 45% for DLBCL. The study found patients on average survived about 5.7 years with the disease.
Possible Complications When Diagnosed with Thyroid Lymphoma
Thyroid lymphoma complications can be serious and life-threatening. These can include difficulties with breathing due to the throat being squeezed (tracheal compression), problems caused by squeezing of the superior vena cava (a large vein carrying blood into your heart, known as superior vena cava syndrome), and difficulties swallowing due to squeezing of the esophagus (esophageal compression).
Complications can also come from the treatment for thyroid lymphoma. These can include underactivity of the iodine-absorbing gland in your neck due to radiation (radiation-associated hypothyroidism), the development of different types of cancers in the thyroid or other nearby organs due to radiation, and different side effects from chemotherapy. This could include nerve damage in the hands and feet due to vincristine, heart failure due to doxorubicin, and conditions like bloody bladder inflammation or bladder cancer due to cyclophosphamide.
- Difficulties with breathing due to tracheal compression
- Superior vena cava syndrome due to superior vena cava compression
- Difficulties swallowing due to esophageal compression
- Underactivity of the thyroid due to radiation (radiation-associated hypothyroidism)
- Radiation-associated cancers of the thyroid or other organs
- Nerve damage due to vincristine (chemotherapy)
- Heart failure due to doxorubicin (chemotherapy)
- Bloody bladder inflammation or bladder cancer due to cyclophosphamide (chemotherapy)
Preventing Thyroid Lymphoma
Lymphoma is a disease where cancer cells grow uncontrollably in the lymphatic cells, which are an important part of your body’s immune system. When this happens in the thyroid gland, these abnormal cells can cause the gland to enlarge. This can lead to various symptoms associated with the thyroid not working properly and becoming enlarged. Patients might also experience symptoms like fever, night sweats, and weight loss due to the lymphoma itself.
In order to diagnose and understand the stage of the lymphoma, various laboratory tests, imaging such as an ultrasound or a CT scan, and a thyroid gland biopsy, which is a procedure where a small piece of the gland is taken for testing, are needed. Depending on the subtype and stage of the lymphoma, treatment options can vary and will often involve a team of specialists. This team may include medical oncologists who specialize in treating cancer with medicines, radiation oncologists who use radiation therapy to treat cancer, pharmacists who focus on cancer medications, and nurses who specialize in caring for cancer patients.
The prognosis, or the likely outcome of the disease, is influenced by factors like the patient’s age, overall health, type of tumor, and the stage of the cancer. However, if primary thyroid lymphoma, which is lymphoma that originates in the thyroid, is identified and treated promptly, the prognosis can be excellent.
