Diagnosing Benign and Malignant Thyroid Nodules
Suspicious and Non-Suspicious Tumors in the Gland
Aug 29, 2009
Some medical estimates state that up to 10% of the general population has thyroid nodules that are detectable by feel (fingertip-palpation), while autopsy studies have revealed that up to 50% of the population has them. Most thyroid nodules do not pose a problem, while others cause difficulty with swallowing or breathing and others cause an imbalance in thyroid hormone levels.
Even less common are thyroid nodules that contain cancer cells or “malignancy” but most are benign, meaning they are not cancerous. Malignant thyroid nodules are diagnosed more often in women than in men and are also found more often in younger patients under the age of 20-years and older patients at the age of 70-years and older.
Common Vs Suspicious Nodules
The most commonly detected thyroid nodules in the general population are those that are not solid but contain fluid within them, giving them a soft texture or what are sometimes referred to as “cystic nodules”. These type do not pose a risk of containing malignancy, the vast majority of the time and so are usually not referred for additional testing beyond palpation to determine their size and texture.
Having a number of nodules in one’s thyroid gland (multi-nodular), rather than a singular one also helps to rule out the possibility of thyroid cancer. Lone thyroid nodules and those that are very firm in texture are often referred for additional testing that might include tissue biopsy and/or imaging tests.
Hot Nodules
This term is used to describe thyroid nodules that begin to act like normal thyroid tissue, meaning they absorb iodine and begin producing thyroid hormone as if they are part of the gland. A nuclear imaging scan, followed by oral or intravenous dosing of a patient with radioactive iodine, will show that the nodule is a “hot area” on the scan which means it is absorbing large amounts of iodine within the thyroid gland. These type are rarely suspicious of containing malignancy but often cause hyperthyroidism in patients who have them. This may require surgical removal of the nodule and or part or all of the thyroid gland.
Solid Cold Nodules and Malignancy
These type have a firm texture when palpated and may be found singular or less-commonly within a group of nodules. These, type can take up space in the thyroid gland and cause a degree of hypothyroidism, meaning slowed production of thyroid hormone. They are often also of significant size that presents more concern, which would be in the 3-centimeter and larger category. Even if nodules are smaller but are of solid texture, they are often referred for imaging scans. This might include an MRI scan with contrast, a thyroid ultrasound or a Radionuclide Scan in which a dose of “radioactive iodine isotope-123” is administered to a patient, followed by taking images with a nuclear camera.
If a nodule shows up as a “cold area” on the test result, meaning an area that appears blank because it did not absorb the radioactive iodine, this can indicate malignancy and the patient would likely be referred for thyroid removal. The tumor/nodule would either require removal of the affected lobe, referred to as a “lobectomy” or “partial thyroidectomy” (sub-total) but more commonly will require total thyroidectomy, followed by radiation treatment to eradicate any remaining cancer cells.
The patient would afterward require thyroid hormone replacement due to the missing thyroid gland and resulting hypothyroidism but hormone therapy may be delayed for weeks following completion of radiation treatments. The most common malignancies found in thyroid nodules, are papillary, follicular, medullary and anaplastic (most radical type) cancers.
Tissue Biopsies
In some cases the diagnostic tests for detecting or ruling-out malignant cells in thyroid nodules are tissue biopsies. Some nodules require surgical biopsy, if they are found growing toward the inside of the throat but most are detectable from the outside of the throat. These can be biopsied by “Fine-Needle Aspiration”, a test using a long hypodermic needle, inserted into the neck to extract a tissue sample after the patient is given a local anesthesia. The sample is then analyzed for detection of any suspicious cells.
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