They occur when thyroid cells form a bulge in the thyroid gland and abnormal growths are created.
Although benign (non-cancerous) thyroid nodules are the most common, there is also a small chance of developing malignant thyroid nodules, that is, they contain cancer cells in them.
Most thyroid nodules need some type of evaluation to be able to diagnose and treat thyroid cancer early. Some people have one nodule while others have many.
Thyroid nodules can be solid tissue or tissue filled with blood or other fluid.
Thyroid nodules are quite common, with half of all people having at least one nodule by the age of 60.
There are usually no symptoms when thyroid nodules appear.
These are often discovered accidentally during a routine physical exam or imaging tests like CT scans or neck ultrasounds done for completely unrelated reasons.
Occasionally, patients find thyroid nodules noticing a lump on their neck while looking in a mirror, buttoning their neck, or fastening a necklace.
Abnormal thyroid function tests can occasionally be the reason a thyroid nodule is found.
Thyroid nodules can produce excess amounts of thyroid hormone, triiodothyronine (T3) and thyroxine (T4), which cause hyperthyroidism , and you may have the following symptoms:
- Irritability or moodiness
- Nervousness, hyperactivity.
- Sweat or sensitivity to high temperatures.
- Fast heart rate
- Trembling in the hand.
- Hair loss.
- Frequent bowel movements or diarrhea.
- Missed or light menstrual periods.
However, most thyroid nodules, including those that are cancerous, don’t actually work, which means tests like TSH are normal.
Patients with thyroid nodules rarely have pain in the ear, neck, or jaw.
When a nodule is so large that it has the ability to compress the esophagus or trachea, it can cause a slight tickle in the throat and difficulty swallowing and breathing.
Even less commonly, hoarseness can be caused if the nodule invades the nerve that controls the vocal cords, but this is generally linked to thyroid cancer.
Important points to remember are the following:
- Even when the nodule is cancerous, the tests are usually normal.
- Thyroid nodules usually do not cause symptoms.
- Having a doctor carefully check your neck is the best way to find and make sure of the presence of the thyroid nodule.
We don’t know what causes most thyroid nodules, but they are extremely common.
Nodules run in families, which means they can have a genetic basis.
Approximately all people over the age of 60 have one or more nodules that can be found by medical examination or imaging tests. Virtually all of these nodules are benign.
One of the diseases to which the appearance of these nodules is most attributed is Hashimoto’s thyroiditis.
Iodine deficiency is also known to cause thyroid nodules.
In addition, the risk of thyroid nodules is higher in women than in men, the incidence increases with age and is higher in people exposed to radiation from medical treatments or who have Hashimoto’s disease, which is the most common cause of hypothyroidism ( underactive thyroid).
Your doctor can detect a thyroid nodule by examining your neck to feel for your thyroid gland.
If you have a thyroid nodule, your doctor may use ultrasound to see what the nodule looks like and may take a small sample of the nodule cells to rule out cancer.
When samples of nodule cells are taken for testing, the procedure is called a biopsy or fine needle aspiration (FNA).
The cells are examined microscopically by a pathologist. The biopsy involves the use of a very small needle to capture the cells.
This procedure can be uncomfortable, but not painful.
To help reduce your discomfort, your doctor may numb the skin area with a topical anesthetic, which is a cream that contains short-acting pain relievers.
Also, your doctor may take a blood sample to measure the levels of T3 and T4: thyroid hormones and thyroid-stimulating hormone (TSH).
TSH is a hormone produced by the pituitary gland to regulate the production of T3 and T4 in the thyroid.
These blood tests cannot detect whether a thyroid nodule is cancerous, but they will help rule out other thyroid conditions.
Once the nodule is discovered, your doctor will try to determine if the rest of the thyroid is healthy or if the entire thyroid gland has been affected by a more general disorder, such as hyperthyroidism or hypothyroidism.
Your doctor will look at the thyroid to see if the gland is enlarged and if there are single or multiple nodules.
Initial laboratory tests may include measurement of thyroid hormone (thyroxine or T4) and thyroid stimulating hormone (TSH) in the blood to determine if the thyroid is working normally.
Since it is generally not possible to determine whether a thyroid nodule is cancerous by physical examination and blood tests alone, evaluation of thyroid nodules often includes specialized tests such as thyroid ultrasound and fine needle biopsy.
A key tool for evaluating these nodules is thyroid ultrasound.
This type of test takes a picture of the thyroid using high-frequency sound waves.
Thanks to the precision of this test, it is possible to see precisely if this is a cystic nodule (formed by water) or if it is a solid nodule, in turn, you can identify the specific size of the nodule.
Ultrasound can help identify suspicious nodules since some ultrasound features of thyroid nodules are more common in thyroid cancer than in non-cancerous nodules.
This type of test allows us to identify nodules that are too small to feel on a physical evaluation.
This procedure can be performed by inserting a fine needle into the nodule, when a biopsy is deemed necessary.
Thyroid ultrasound is used after the initial medical exam, to check if the nodules are growing or shrinking over time, or if they require surgery.
Ultrasound is a painless test that many doctors can perform in their own office.
Fine needle aspiration biopsy
When a fine needle nodule biopsy is mentioned, it may be scary at first, but in reality this needle is so small that in most cases local anesthesia is not needed.
For this procedure, the doctor will remove the cells from the thyroid nodule thanks to a biopsy in which a fine needle will be used.
This simple procedure is often done in the doctor’s office.
Sometimes medications such as blood thinners may need to be stopped for a few days before the procedure.
Otherwise, the biopsy usually does not require any other special preparation (without fasting).
Generally, after the biopsy, patients can immediately return to work and home without even applying a band-aid.
Usually, several samples will be taken from different parts of the nodule to give your doctor the best chance of finding cancer cells if they are present.
The cells are then examined under a microscope by a pathologist.
Commonly, the results of these tests indicate one of the following findings:
The nodule is benign (not cancerous).
Up to 80% of biopsies show this result. The risk of missing a cancer when the biopsy is benign is generally less than 3 in 100 tests or 3%.
This is even lower when an experienced pathologist at a major medical center reviews the biopsy.
Generally, benign thyroid nodules do not need to be removed unless they are causing symptoms such as choking or difficulty swallowing. Follow-up ultrasound exams are important.
In most cases, if the nodule grows over time, another biopsy is recommended.
If the nodule is malignant (cancerous)
Approximately 5% of biopsies have this result and, very frequently, it is caused by capillary cancer, which is the most common type of thyroid cancer.
If the biopsy results in a 50-70% risk of cancer, it is considered suspicious.
The next procedure to follow after seeing the results is the surgical removal of the thyroid, always under the recommendation of a surgeon and endocrinologist.
If the nodule is indeterminate
We see this diagnosis as the result of several analyzes and can be seen in up to 20% of cases.
We see the significance of this result if the appropriate number of cells are removed during the fine needle biopsy, but nevertheless, the following examination under the microscope cannot reliably define whether these cells are cancerous or not.
The biopsy result may be indeterminate if the nodule is defined as a follicular lesion. Between 20 and 30% of the time, these nodules are cancerous.
However, the definitive and safe diagnosis can only be made through surgery.
Because the chances that the nodule is not cancerous are better with surgery (between 70 and 80%), the side of the thyroid plus the nodule is removed.
If cancer is found, the remaining thyroid gland usually must also be removed.
If the surgery confirms the absence of cancer, it is not necessary to perform a second surgery to complete the thyroidectomy.
If the cells of the nodule do not have characteristics that could fit into some of the other diagnostic categories, it is considered indeterminate. This result is known as a follicular lesion of determined significance or atypia.
The results that derive from this category very rarely contain cancer, so it is recommended to repeat the surgery to remove the half of the thyroid that has the nodule.
Depending on your doctor’s clinical judgment, these nodules may require a second evaluation or another fine needle biopsy.
Nuclear thyroid exams
Nuclear exploration of the thyroid has been frequently performed in the past to evaluate thyroid nodules.
However, the use of ultrasound and thyroid biopsy has proven to be so accurate and sensitive that nuclear scanning is no longer considered a first-line evaluation method.
This test still plays an important role in the evaluation and diagnosis of foreign nodules that cause hyperthyroidism.
In this situation, a nuclear thyroid scan may suggest that no further evaluation or biopsy is needed.
In most other situations, ultrasound and neck biopsy remain the best and most accurate way to evaluate all types of thyroid nodules.
New tests that examine the genes in the DNA of thyroid nodules are currently available and more are being developed.
These tests can provide useful information about whether the cancer may be present or absent. These tests are particularly useful when the specimen evaluated by the pathologist is indeterminate.
The samples obtained during the normal biopsy are also analyzed with these specialized tests. There are also specialized blood tests that can help in the evaluation of thyroid nodules.
Currently, these tests are only available in specialized centers, although their availability increases over time.
Ask your doctor if these tests are available and could be helpful in evaluating your thyroid nodule.
Most thyroid nodules are not cancerous, and your doctor will simply monitor you with ultrasound and a physical exam at least once a year.
If the nodule continues to grow and / or cause breathing / swallowing problems or develop cancerous features over time, your doctor may recommend surgical removal. If the nodule has cancer cells, an endocrine surgeon will remove it.
Nodules that produce too many thyroid hormones T3 and T4 can be treated with radioactive iodine or alcohol ablation.
Radioactive iodine is given in pill form and causes the thyroid gland to contract and make less thyroid hormone. Radioactive iodine is only absorbed by the thyroid gland, so it does not harm other cells within your body.
Alcohol ablation involves injecting alcohol into the thyroid nodule (s) with a very small needle. Treatment makes the nodules shrink and make less thyroid hormone.