Thyroid Nodules

What are thyroid nodules?  Basically, they are lumps in the thyroid.  The thyroid is a butterfly shaped gland in the lower, anterior area of your neck.  It secretes thyroid hormone that controls metabolism and protein production throughout the body.  Many studies find that nodules are common.  Luckily most do not become clinically significant, but about 5% can be a thyroid cancer.

Nodules can be benign (noncancerous) or malignant (cancerous).  There are several types of benign nodules.  Hyperplastic nodules are made up of abnormal over growth of normal cells.  Colloid nodules are partly solid and partly cystic.  The cystic areas are filled with a fluid called colloid, which is created when the thyroid produces thyroid hormone.    A pure cyst can cause a lump and is rarely a cancer.  An adenoma is a benign tumor.  Sometimes the difference between an adenoma and a cancer (carcinoma) can only be determined after surgical removal.    Hashimoto’s thyroiditis, an autoimmune inflammation of the thyroid gland can frequently cause a nodular goiter.  A multinodular goiter is a thyroid with multiple nodules, whereas a uninodular goiter is made up of only one nodule.  The word "goiter” is a term that means enlarged thyroid.  This can be caused by one or multiple nodules or by diffuse enlargement of the thyroid gland.

As noted above, about 5% of nodules can be malignant.  There are several types of thyroid carcinoma (cancer).  Papillary thyroid carcinoma is by far the most common, making up about 80%.  Follicular thyroid carcinoma is the second most common.  It can only be differentiated from a benign follicular adenoma by removal and examination of the entire tumor by a pathologist.  Anaplastic carcinoma makes up less than 5% of thyroid cancer.  It is very fast growing and very aggressive.  Treatment is difficult and the prognosis is poor.  Another uncommon cancer (< 5%) is called medullary thyroid carcinoma.  It can be linked to genetic risk factors.

Nodules are often found by doctors during a physical exam.  Some can be seen on the front of the neck and are brought to someone’s attention when someone notices it moving with swallowing or talking.  Others are found coincidentally on imaging studies ordered to evaluate other problems, such as neck pain, lung problems, carotid artery blockage, etc.

The evaluation of the lesions in the thyroid is best done with ultrasound.  Sometimes a CT (CAT) scan or magnetic resonance imaging (MRI) is used.  A blood test to evaluate the thyroid stimulating hormone (TSH) level will tell if the thyroid is functioning normally.  If the TSH is low, meaning the thyroid is over functioning, then a radioactive iodine uptake and scan needs to be done.  Once nodules are larger than 1-1.5 cm (0.4-0.6 inches) they should be biopsied using fine needle aspiration techniques.

Once a nodule is located in your thyroid, a discussion with your doctor will determine the best course of action for you.