Thyroid Nodules
What are thyroid nodules?
The thyroid gland is located in the lower front of the neck, below the voicebox (larynx) and above the collarbones.
A thyroid nodule is a lump in or on the thyroid gland. Thyroid nodules are detected in about 6 percent of women and 1-2 percent of men; they occur 10 times as often in older individuals, but are usually not diagnosed.
Any time a lump is discovered in thyroid tissue, the possibility of malignancy (cancer) must be considered. More than 95 percent of thyroid nodules are benign (noncancerous), but tests are needed to determine if a nodule is cancerous.
Benign nodules include:
- Multinodular goiter, also called a nontoxic goiter. The word goiter means the thyroid gland has grown too large. This usually happens when the pituitary gland in the brain creates too much thyroid stimulating hormone. If the goiter is small, the problem may be treated with thyroid hormone pills. Surgery is needed if the goiter is large or does not stop growing after taking thyroid hormones. A large thyroid gland can press against the trachea (windpipe) or esophagus (food tube) and cause difficult breathing or eating.
- Benign follicular adenomas. The word follicular means the cells look like a group of small circles under a microscope. If the follicular cells are contained within the nodule, the condition is called benign. If the cells have invaded the surrounding tissue, the diagnosis is cancer.
- Thyroid cysts are nodules filled with fluid. If a nodule has both fluid and solid parts, it is called a complex nodule. They need to be surgically removed if they cause neck pain or difficultly swallowing.
What causes thyroid nodules?
Nodules can be caused by a simple overgrowth of normal thyroid tissue, fluid-filled cysts, inflammation (thyroiditis) or a tumor (either benign or cancerous). Most nodules were surgically removed until the 1980s. In retrospect, this approach led to many unnecessary operations, since fewer than 10 percent of the removed nodules proved to be cancerous. Most removed nodules could have simply been observed or treated medically.
Chronic thyroiditis (Hashimoto's disease) is an inflammation of the thyroid gland that develops slowly. It frequently leads to a decreased function of the thyroid (hypothyroidism). Thyroiditis occurs when the body's immune system destroys the cells in the thyroid gland. Chronic thyroiditis is most common in women and people with a family history of thyroid disease.
What are the symptoms of thyroid nodules?
Many patients with thyroid nodules have no symptoms and are found by chance to have a lump in the thyroid gland during a routine physical exam or an imaging study done for unrelated reasons. A minority of patients may become aware of a gradually enlarging lump in the front portion of the neck or may experience a vague pressure sensation or discomfort when swallowing. A lump in the neck should be brought to the attention of your physician, even in the absence of symptoms.How are thyroid nodules diagnosed?
Fine Needle Biopsy
A thyroid fine needle biopsy is a simple procedure that can be performed in the physician's office. Some physicians numb the skin over the nodule prior to the biopsy, but it is not necessary to be put to sleep, and patients can usually return to work or home afterward with no ill effects.
This test provides information that no other test can offer short of surgery. A thyroid needle biopsy will provide sufficient information on which to base a treatment decision more than 85 percent of the time if an ultrasound is used.
Use of fine needle biopsy has drastically reduced the number of patients who have undergone unnecessary operations for benign nodules. However, about 10-20 percent of biopsy specimens are interpreted as inconclusive or inadequate, that is, the pathologist cannot be certain whether the nodule is cancerous or benign.
In such cases, a physician who is experienced with thyroid disease can use other criteria to make a decision about whether to operate.
Thyroid Scan
A thyroid scan is a picture of the thyroid gland taken after a small dose of a radioactive isotope normally concentrated by thyroid cells has been injected or swallowed. The scan tells whether the nodule is hyperfunctioning (a "hot" nodule). Because cancer is rarely found in hot nodules, a scan showing a hot nodule eliminates the need for fine needle biopsy. If a hot nodule causes hyperthyroidism, it can be treated with radioiodine or surgery.
Neither a thyroid scan nor radioiodine treatment should ever be given to a pregnant woman. Small amounts of radioactive iodine will be excreted in breast milk. Since radioiodine could permanently damage the infant's thyroid, breast-feeding is not allowed for women undergoing radioiodine treatment.
Ultrasound
In thyroid ultrasoundography, high-frequency sound waves pass through the skin and are reflected back to the machine to create detailed images of the thyroid. It can visualize nodules as small as 2-3 millimeters. Ultrasound distinguishes thyroid cysts (fluid-filled nodules) from solid nodules. Recent advances in ultrasonography helps physicians identify nodules which are more likely to be cancerous.
Thyroid ultrasonography is also used for guidance of a fine needle for aspirating thyroid nodules. Ultrasound guidance enables physicians to biopsy the nodule to obtain an adequate amount of material for interpretation.
Even when a thyroid biopsy sample is reported as benign, the size of the nodule should be monitored. A thyroid ultrasound examination provides an objective and precise method for detection of a change in the size of the nodule. A nodule with a benign biopsy that is stable or decreasing in size is unlikely to be malignant or require surgical treatment.
How are thyroid nodules treated?
Most patients who appear to have benign nodules require no specific treatment. Some physicians prescribe the hormone levothyroxine with hopes of preventing nodule growth or reducing the size of cold nodules. Radioiodine may be used to treat hot nodules.
In a patient with a known thyroid nodule, the initial step is to determine the risk for cancer. High-risk factors include:- Being male under age 40
- A history of radiation therapy to the head or neck
- Big lymph nodes in the neck
- Problems swallowing
- Problems speaking
- A family history of thyroid cancer
If the lesion is benign, the patient is monitored via ultrasound for the growth of the nodule or development of new nodules. If there is growth, another biopsy may be performed. If the lesion is malignant, the patient is referred to one of the Thyroid Cancer Program surgeons for removal of the thyroid.
About 10 percent of the time, the pathologist is unable to provide a diagnosis due to lack of specimen from the aspiration. That suggests an increased risk for malignancy, which may require surgery or monitoring.
In most surgeries, the entire thyroid is removed (total thyroidectomy). Lymph nodes also may be removed to determine if the tumor has spread beyond the thyroid gland. Subsequent therapy depends upon the findings at the time of surgery. Some patients may be placed on thyroid hormone and followed with blood tests and ultrasound examinations, while other will receive radioactive iodine to destroy the residual thyroid tissue and then be followed with blood tests and ultrasounds.
Using this type of therapy, the majority of cancers will be either cured or controlled and less than 20 percent will recur. In the case of aggressive disease, a patient may qualify for clinical trials with newer therapies such as targeted chemotherapies.
Key points
- A thyroid nodule is a lump in or on the thyroid gland. Thyroid nodules are detected in about 6 percent of women and 1-2 percent of men; they occur 10 times as often in older individuals, but are usually not diagnosed.
- Any time a lump is discovered in thyroid tissue, the possibility of cancer must be considered.
- More than 95 percent of thyroid nodules are benign.
Next steps
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells you.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your provider if you have questions.
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