A thyroid nodule is a growth of thyroid cells that forms a lump within the thyroid gland. Thyroid nodules are quite common, with as many as half of all people having at least one nodule by the age of 60.
There are several different types of thyroid nodules, including:
• Thyroid cysts are typically filled with fluid and usually benign.
• Solid thyroid nodules are nodules filled with cells and protein.
• Complex thyroid nodules (cystic and solid) contain both fluid and solid components.
• Multinodular goiter describes an enlarged thyroid gland containing multiple thyroid nodules.
• Hyperfunctioning thyroid nodules produce excessive amounts of thyroid hormone, which may lead to the development of hyperthyroidism.
Although the vast majority of thyroid nodules are benign (noncancerous), a small proportion can contain thyroid cancer. In order to diagnose and treat thyroid cancer at the earliest stage, all thyroid nodules should be thoroughly evaluated when detected.
Risk Factors and Causes of Thyroid Nodules
Although the causes of thyroid nodules are unknown, they are very common. Fortunately, the vast majority of thyroid nodules are benign.
There are several risk factors that can increase an individual’s chances of developing thyroid nodules. Hashimoto’s thyroiditis, the most common cause of hypothyroidism, is associated with an increased risk of thyroid nodules.
In addition, women are more likely than men to develop thyroid nodules. The chance of developing thyroid nodules increases with age as well. Other risk factors include: Radiation exposure, having a family history of thyroid nodules, and an iodine deficient state.
Symptoms of Thyroid Nodules
Most thyroid nodules do not cause symptoms. However, hyperfunctioning (overactive) thyroid nodules can cause hyperthyroidism symptoms.
Most often, thyroid nodules are discovered incidentally during a routine physical examination, or during imaging studies performed for unrelated reasons. Occasionally, individuals detect thyroid nodules themselves by feeling or noticing a lump in their neck. Sometimes, if a nodule is very large, it may cause neck or facial pain, swollen lymph nodes, shortness of breath, difficulty swallowing, cough unrelated to a cold, voice hoarseness or difficulty speaking.
Fortunately, most thyroid nodules are benign (non-cancerous), so discovering a nodule does not necessarily mean you have cancer. However, it’s still important to see your physician for a thorough evaluation, since early detection provides the best opportunity for successful outcomes.
Diagnosing Thyroid Nodules
If you, or your physician, suspect a thyroid nodule, the workup usually involves performing a physical exam to check your thyroid gland to determine if it’s enlarged and whether a single or multiple thyroid nodules are present.
In addition, your physician will order thyroid blood tests to measure thyroid hormone levels to determine whether your thyroid is functioning normally.
The evaluation of thyroid nodules also includes specialized tests, particularly a thyroid ultrasound and a biopsy, which are the most reliable and accurate diagnostic methods for evaluating all types of thyroid nodules.
Thyroid ultrasound is a key tool for evaluating thyroid nodules. Ultrasound is an imaging study that uses high-frequency sound waves to obtain an image of the thyroid. This non-invasive test can help physicians determine the number and size of nodules on the thyroid, as well as determine whether a nodule is solid, or filled with fluid. Ultrasound can identify nodules that are too small to feel during a physical exam, and also nodules located below the clavicle and behind the thyroid gland. It also helps physicians to identify suspicious nodules that have characteristics that are more common in thyroid cancer than in noncancerous nodules. Thyroid ultrasound is often used to accurately guide a needle during fine needle biopsy. It’s also an important tool for monitoring thyroid nodules that do not require surgery in order to determine if they are growing or shrinking over time.
Fine Needle Aspiration (FNA) Biopsy
Fine Needle Aspiration (FNA) is the most reliable way to determine whether a nodule is benign or malignant (cancerous). FNA biopsy is an outpatient procedure in which the area around the nodule is numbed and a thin, hollow needle inserted into the nodule to aspirate (take out) some cells into a syringe. The physician usually repeats this process a few times, taking samples from several areas of the nodule. This procedure is generally done under ultrasound guidance for preciseness and to ensure that enough cells are extracted for evaluation. The extracted cells are then examined under a microscope by pathologists to determine if they are benign or cancerous. In cases where a diagnosis is not clear after an FNA biopsy, the specimen can be sent for genetic testing for further evaluation.
Because the thyroid gland is so close to the vocal cords, thyroid nodules may sometimes affect them. During a laryngoscopy procedure, a thin, flexible scope is guided to the larynx, allowing the physician to examine the throat and larynx for nodules and other abnormalities, as well as determine how well the vocal cords are functioning.
A thyroid scan is a nuclear medicine imaging study that uses a radioactive iodine tracer to determine the function of the thyroid gland. Typically, this test is only used in cases of hyperthyroidism with the presence of a thyroid nodule. During the test, nodules that produce excess thyroid hormone (called hot nodules) show up on the scan because they absorb more of the iodine tracer. If the nodule absorbs less iodine than the rest of the thyroid gland, then the nodule is called a “cold nodule.” These nodules have a higher chance of malignancy. Hot nodules are almost always benign (noncancerous).
Molecular markers can be a helpful diagnostic tool, particularly for indeterminate thyroid nodules (nodules that are not clearly identified as benign or cancerous during a biopsy). These indeterminate cases were traditionally managed with surgery to establish a definitive diagnosis. However, progress continues to be made in developing molecular markers for use in fine-needle aspiration specimens in order to determine the relative risk of thyroid cancer and reduce unnecessary surgeries.
Proper diagnosis is vitally important in determining the best treatment protocol personalized for you. At Hoag, our multidisciplinary thyroid program team is highly skilled in the diagnosis and treatment of thyroid nodules.
Treatment Options for Thyroid Nodules
Treatment for thyroid nodules depends on the type of nodule you have.
Treatment for Benign Thyroid Nodules
If a thyroid nodule isn’t cancerous, there are several treatment options:
• Observation. Thyroid nodules that are benign, or too small to biopsy, should be watched closely. This usually means having a physical exam, thyroid blood work, and imaging tests, such as ultrasound at regular intervals. You’re also likely to have another biopsy if the nodule grows larger.
• Surgery. Surgery may be recommended even for a benign nodule if it continues to grow, or develops worrisome characteristics over the course of follow up. Surgery may also be considered for large multinodular goiters, and for nodules causing hyperthyroidism that is unresponsive to other treatments. In addition, nodules diagnosed as indeterminate or suspicious upon biopsy may be surgically removed so they can be fully examined for signs of cancer.
• Radioactive Iodine Therapy. RAI may be used to destroy thyroid tissue if the nodule is hyperfunctioning (producing excessive amounts of thyroid hormone), leading to hyperthyroidism.
Treatment for Cancerous Nodules
Fortunately, the majority of thyroid cancers are curable with early intervention and treatment. Surgery is the most common treatment for thyroid cancer. Therefore, in nodules found to be cancerous (and those found to be highly suspicious of being malignant), surgical removal by an experienced thyroid surgeon is the standard treatment. RAI treatment may also be utilized to aid in the eradication of any remaining thyroid cancer cells.
Hoag Thyroid Cancer Program provides a multidisciplinary team of specialists in surgery, medical oncology, endocrinology, radiology, radiation oncology, pathology, and genetic counseling. Hoag’s team also includes a clinical nurse navigator and other professionals who help patients and their families to cope with the emotional and practical aspects of the disease.
This multidisciplinary team approach ensures that patients receive comprehensive and personalized treatment plans that take into account all facets of care. Treatment plans vary, but most often include surgical resection, radioactive iodine treatment, and other targeted therapies specific to the type and stage of cancer for best outcomes.