Thyroid Mass
A thyroid mass is an abnormal growth or lump that forms in the thyroid gland, the small butterfly-shaped organ at the base of your neck. While these masses are very common—affecting up to 60% of adults—most are not cancerous and don’t cause symptoms, though proper evaluation is important to rule out serious conditions.
Table of contents
- What Is a Thyroid Mass?
- Where the Thyroid Is Located
- Types of Thyroid Masses
- Who Gets Thyroid Masses?
- Symptoms of Thyroid Masses
- Causes and Risk Factors
- How Thyroid Masses Are Diagnosed
- Understanding Cancer Risk
- Treatment Options
- Outlook and Prognosis
What Is a Thyroid Mass?
A thyroid mass, also called a thyroid nodule, is a lump or abnormal growth of cells that forms within the thyroid gland[1][2]. These lumps can be solid or filled with fluid. The American Thyroid Association defines a thyroid nodule as a distinct area within the thyroid gland that looks different from the surrounding thyroid tissue when viewed through medical imaging[5].
Most thyroid masses don’t cause any symptoms, and people often don’t know they have them until a healthcare provider finds one during a routine medical exam or when it shows up on a scan done for another health reason[2][6]. Sometimes people discover a thyroid nodule themselves by noticing a lump in their neck while looking in a mirror, buttoning a collar, or fastening a necklace[6].
Where the Thyroid Is Located
- Thyroid gland
- Neck
- Trachea (windpipe)
- Esophagus
The thyroid is a small, butterfly-shaped endocrine gland (a gland that makes hormones) located at the base of your neck, just below your Adam’s apple and above your breastbone[2][3]. It sits in front of your trachea, or windpipe. The gland has two lobes—a right lobe and a left lobe—connected by a thin piece of tissue called the isthmus[15].
Your thyroid produces hormones that control many important body functions, including your heart rate, body temperature, blood pressure, and metabolism (how your body uses energy)[3][12]. The thyroid uses iodine, a mineral found in some foods and in iodized salt, to make these hormones[15].
Types of Thyroid Masses
Thyroid masses can be classified in several ways. They may be single (solitary nodule) or multiple (more than one nodule), and they can be cystic (fluid-filled) or solid[12]. When someone has multiple nodules, the condition is sometimes called a multinodular goiter[5].
Approximately 23% of solitary nodules represent a dominant nodule within a multinodular goiter[5]. Most thyroid nodules are noncancerous, meaning more than 90% of detected nodules in adults are benign[7][12].
When thyroid masses do turn out to be cancerous, they can be classified into different types. Papillary thyroid cancer is the most common type, making up to 80% of all thyroid cancers. This cancer type grows slowly and, although it often spreads to lymph nodes in the neck, it responds very well to treatment and is highly curable[3]. Follicular thyroid cancer accounts for up to 15% of thyroid cancer diagnoses and is more likely to spread to bones and organs like the lungs[3]. Other less common types include medullary thyroid cancer (about 2% of cases) and anaplastic thyroid cancer (about 2% of cases), which is the most aggressive type[3].
Who Gets Thyroid Masses?
Thyroid nodules are extremely common. Healthcare providers find them in approximately 5% to 7% of adults during a physical examination, but when ultrasound imaging is used, studies reveal that 20% to 76% of adults have thyroid nodules[7][12]. Up to 60% of adults will have at least one thyroid nodule during their lifetime[5]. Autopsy data has shown a 50% prevalence of thyroid nodules larger than one centimeter in patients without previously diagnosed thyroid disease[5].
Thyroid nodules are about four times more common in women than in men[7][12]. When thyroid nodules do become cancerous, women are three times more likely to develop thyroid cancer compared to men[1][3]. The disease is commonly diagnosed in women in their 40s and 50s and men in their 60s and 70s[3].
Thyroid nodules are less common in children, though even children can develop them[3][7].
Symptoms of Thyroid Masses
Most thyroid nodules don’t cause any symptoms[2][6][7]. However, if you have several nodules or large nodules, you may be able to see or feel them[2][12].
In rare cases, thyroid nodules can grow large enough to cause symptoms such as[2][12]:
- Trouble with swallowing or breathing
- Hoarseness or voice changes
- Pain in the front of your neck
- Swelling at the base of the neck
- Enlargement of your thyroid gland (called a goiter)
Some thyroid nodules can make too much thyroid hormone, a condition called hyperthyroidism (overactive thyroid)[2][12]. Symptoms of hyperthyroidism include[12]:
- Unexplained weight loss
- Increased sweating
- Rapid or irregular heartbeat
- Feeling shaky or nervous
- Tremor
- Increased appetite
- Diarrhea and more frequent bowel movements
- Difficulty sleeping
Thyroid nodules may also be associated with low thyroid hormone levels, called hypothyroidism (underactive thyroid)[12]. Symptoms of hypothyroidism include[12]:
- Fatigue
- Weight gain
- Dry, coarse skin and hair
- Constipation
- Depression
- Feeling cold
- Frequent, heavy menstrual periods
Causes and Risk Factors
Researchers don’t know why most thyroid nodules form[7][12]. However, several factors can increase your risk of developing thyroid nodules or thyroid cancer.
Exposure to radiation is a known risk factor for both benign and malignant nodules of the thyroid[1][5]. Significant radiation exposure to the head, neck, or chest—typically from treatment of another cancer—increases the risk of thyroid cancer[1]. People who have been exposed to radiation may develop thyroid nodules at a rate of 2% annually, and the incidence of cancer has been documented as high as 20% to 50% in palpable nodules of previously irradiated thyroid glands[5].
A family history of thyroid cancer also increases risk. If an immediate family member has papillary thyroid cancer, their first-degree relatives are at increased risk for developing it (2 to 10 times higher risk)[23]. About a quarter of people with medullary thyroid cancer have a family history of the disease, and a faulty gene (genetic mutation) may be to blame[3].
Other factors that can increase the risk of thyroid nodules include[5][7][12]:
- Living in countries where food isn’t fortified with iodine
- Increasing age
- Iron-deficiency anemia
- Smoking
- Obesity
- Metabolic syndrome
- Alcohol consumption
- Increased levels of insulin-like growth factor-1 (a hormone)
- Uterine fibroids
How Thyroid Masses Are Diagnosed
When a thyroid nodule is found, your healthcare provider will check the lump or nodule in your neck to rule out cancer and to make sure your thyroid is working properly[9][22]. Tests might include:
Thyroid function tests: These blood tests measure levels of thyroid-stimulating hormone (TSH) and hormones your thyroid gland makes. These tests can show if you have too much or too little thyroid hormone[9][22]. Blood tests may also check for antithyroid antibodies[15].
Ultrasound: This test uses sound waves to make images of your thyroid gland. A thyroid ultrasound shows the shape and structure of nodules[9][15][22].
Fine-needle aspiration biopsy: A biopsy of nodules can make sure there’s no cancer. During this procedure, a healthcare professional puts a very thin needle in the nodule and removes a sample of cells. Ultrasound imaging might guide the needle. The biopsy most often is done in a healthcare professional’s office and takes about 20 minutes with few risks. The samples go to a lab for study under a microscope[9][15][22].
Thyroid scan: A thyroid scan tells more about the thyroid nodules. During this test, radioactive iodine is put into a vein in your arm. You then lie on a table while a special camera makes an image of your thyroid on a computer screen. Nodules that make too much thyroid hormone, called hot nodules, show up on the scan because they take up more iodine than typical thyroid tissue. Hot nodules are rarely cancer. Some nodules take up less iodine and are called cold nodules. They can be cancer, but a thyroid scan can’t tell which cold nodules are cancer and which are not[9][22].
Understanding Cancer Risk
Although more than 90% of detected nodules are noncancerous, thyroid nodules are clinically important because they may represent thyroid cancer in approximately 4.0% to 6.5% of cases[5][7][12]. Only about 3 out of 20 thyroid nodules turn out to be cancerous[3].
You or your healthcare provider might feel a lump or growth in your neck. Don’t panic if you have a thyroid nodule—most nodules are benign (not cancer)[3]. Only a small number of thyroid nodules are diagnosed as cancer[15].
Most thyroid cancers are highly curable, with treatments that are very successful. Thyroid cancer is generally highly treatable, with an excellent cure rate[3]. The overall 5-year survival rate for people with thyroid cancer is 98%, with long-term survival being 95% or higher[13]. This is especially true if the cancer is localized and has not spread to any surrounding areas[14].
Close to 53,000 Americans receive a thyroid cancer diagnosis every year. About 2,000 deaths result from the disease each year[3][13].
Treatment Options
Treatment depends on the type of thyroid nodule you have[9][22].
For Noncancerous Thyroid Nodules
Watchful waiting: This means simply watching your condition. It often means having a physical exam and thyroid function tests regularly[9][22]. Many thyroid cancers remain stable, microscopic, and slow-growing[13].
Thyroid hormone therapy: Some nodules may be treated with thyroid hormone medication[9][22]. If you have hypothyroidism, it is usually treated and controlled with thyroid hormone therapy using levothyroxine, a drug that replaces thyroxine, which is normally made by the thyroid[8].
Radioiodine therapy: If nodules make too much thyroid hormone, treatment options include radioactive iodine therapy. The thyroid gland absorbs nearly all the iodine in the body, so radioiodine treatment targets and destroys cancerous cells located in the thyroid gland as well as other areas of the body that have thyroid cancer cells[14].
Surgery: In some cases, surgery may be needed to remove the nodule[9][22].
For Thyroid Cancer
The treatment options for patients with thyroid cancer include[13][14]:
Surgical removal of the thyroid gland: Surgery is the main treatment for thyroid nodules and tumors. Doctors may remove part of or the entire thyroid. A thyroidectomy removes the thyroid gland. If nearly all of the gland is removed, it is known as a near-total thyroidectomy. If the entire thyroid gland is removed, it is called a total thyroidectomy. A lobectomy removes the lobe, or portion of the thyroid gland, that contains the cancer. If the cancer has spread to surrounding lymph nodes, they will be taken out in addition to the affected thyroid[14].
After a near-total or total thyroidectomy, a patient will need to take daily thyroid hormone pills to account for their missing thyroid gland[14].
Radioactive iodine therapy: This is often used as a follow-up to surgery and is only considered for treatment of papillary thyroid cancer and follicular thyroid cancer, not for medullary thyroid cancer[14].
Radiation therapy: High energy X-rays or other types of radiation can be used to kill cancer cells. This form of treatment can be used in more advanced thyroid cancer[14].
Targeted therapy and molecular-targeted therapies with tyrosine kinase inhibitors: These newer treatment options are available for certain types of thyroid cancer[13][14].
Outlook and Prognosis
The prognosis for most patients with thyroid nodules is excellent[1]. Most thyroid nodules are noncancerous and don’t require treatment beyond monitoring.
For those with thyroid cancer, the prognosis is also very good. Most thyroid cancers are highly curable and very treatable. The prognosis for most patients with thyroid cancer is excellent, meaning that the thyroid cancer is not life-threatening and very treatable[10]. Treatments for most thyroid cancers are very successful, and the increasing treatment options for patients with thyroid cancer have kept the mortality rate from this cancer low, despite the increase in its incidence[13].
Early diagnosis and appropriate treatment can improve prognosis and reduce mortality[13]. The earlier cancer can be diagnosed and treated, the better the outcome[7][12].