Thyroid Nodules

WHAT IS A THYROID NODULE?

A thyroid nodule is a growth or lump in the thyroid gland typically either felt on the front low part of the neck or seen by ultrasound. More than 90% of thyroid nodules are benign, but in some cases, they can signify thyroid cancers. Most nodules are small and not typically noticeable. However, if a lump in the thyroid is felt, this definitely should be evaluated by ultrasound to further characterize the nodule. Thyroid nodules are very common and become more common as people get older, but they can occur at any age. Overall, 5% of women and 1% of men have thyroid nodules that can be felt on physical examination. Autopsy studies have shown that very small nodules are even more common, appearing in as many of half the population that are 65 or older.

Thyroid Surgery

What if I see a lump on my neck?

Most nodules are too small to make a noticeable difference in the appearance of the neck. However, visible nodules should always be evaluated. In children and teenagers, thyroid nodules are markedly different than in adults. Cancer rates for thyroid nodules in children run between 20-30% and any nodule in a child should be evaluated immediately. Early stage thyroid cancer has no symptoms! There is no way to tell (by symptoms) whether someone has early stage thyroid cancer. In later stages, concerning symptoms for thyroid cancer would include:

Abnormally large lymph nodes or swollen glands in the neck that do not go away after more than a month.
Hoarseness present for more than three to four weeks that does not go away.
Difficulty breathing or shortness of breath.
Difficulty swallowing hard or firm foods, pills, or a sensation of a lump low in the neck when swallowing.
Unexplained chronic cough or chronic throat clearing.

TYPES OF THYROID NODULES

The best way to characterize a thyroid nodule is with ultrasound. Today’s high-resolution ultrasound allows for a definitive look inside the thyroid, and ultrasound characteristics can be used to judge the potential dangers associated with the thyroid nodule.

High-Risk Thyroid Nodules

There are particular characteristics seen on ultrasound which can determine that a thyroid nodule is at high risk for thyroid cancer. These would include the presence of microcalcifications. These are small bright white dots that appear in the background of a solid thyroid nodule. More than 90% of patients with microcalcifications turn out to have thyroid cancer. Microcalcifications are a concerning feature seen on ultrasound and if a nodule is greater than 1.0 cm with this type of feature then it definitely needs an FNA biopsy. Most thyroid nodules are smooth and regular. When the borders are irregular, we see a high rate of cancer in those nodules. The American Thyroid Association estimates between 70-90% of those with irregular borders or if the borders are extending outside the thyroid capsule that those characteristics are indicative of a high risk of cancer.

Intermediate Risk Nodules

Most of the time when a thyroid nodule is evaluated, you will find smooth, regular borders, and this puts the nodule at a lower cancer risk than described above. When we look at thyroid nodules on ultrasound, we compare the density of the nodule to the density of the surrounding thyroid tissue. If the nodule is darker than the surrounding tissue then this is called a hypoechoic thyroid nodule and typically these lesions are at intermediate risk for thyroid cancer, meaning 10-20% of patients with these would turn out to have thyroid cancer.

Low-Risk Nodules

If the nodule density matches that of the surrounding thyroid it is described as isoechoic and this carries a lower risk of malignancy where we see roughly a 5-10% rate. In that same category of low risk are hyperechoic nodules which appear brighter on ultrasound than the surrounding thyroid tissue. While many thyroid nodules are solid, there are some that have a mixture of solid and fluid within those. These are sometimes called complex cysts or mixed solid and cystic nodules. These tend to carry either a low or very low risk of malignancy depending upon the structure.

Very-Low Risk Nodules

Finally, there is a type of nodule called spongiform which has a very distinct ultrasound pattern. This is in the lowest risk category where less than 3% of those lesions ever turn out to be cancer. Because they are at very low risk, they can be observed safely without FNA when they are smaller than 2 cm. When they exceed this size, FNA biopsy is recommended for them.

Thyroid Cysts

Also seen very frequently in the thyroid are thyroid cysts. These are not true nodules. They are completely fluid filled and have no solid component and as such pose no risk for thyroid cancer and do not need fine needle aspiration biopsy. Multiple thyroid cysts within the thyroid are frequently found, especially among women. This is very common and carries no cancer risks! So, if you’ve been told you have a multicystic thyroid gland, have no fear! Cysts not only pose no risk of cancer, but they also have no effect on thyroid function. Occasionally, thyroid cysts will become very large and can be unsightly. Ultrasound guided needle drainage can reduce the cyst. Some thyroid cysts reaccumulate immediately after drainage. Thyroid cyst sclerosis can be employed in many of these cases to eliminate the problem. In rare circumstances, cysts need to be removed surgically. As with all thyroid surgery, choose your surgeon wisely as complication rates vary with experience. Removing a thyroid cyst surgically is a very low risk procedure in the hands of an experienced, high-volume thyroid surgeon.

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Keith Forwith

Thyroid Nodules

WHAT IS A THYROID NODULE?

Thyroid Surgery

What if I see a lump on my neck?

Keith Forwith

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