by Adnan Karavelic MD FRCPC
October 18, 2023
A thyroid nodule is an abnormal growth in the thyroid gland. Large nodules can be felt or seen as a lump in the front of the neck. Finding a nodule in your thyroid gland does not necessarily mean that you have cancer. A nodule can be caused by non-cancerous growth or by cancer. Additional tests are required to determine the cause of the nodule.
An imaging test called an ultrasound is usually performed to see the nodule inside the thyroid gland. The ultrasound allows your doctor to measure the nodule and to see if it is solid or filled with fluid. During the ultrasound, a small sample of the nodule may be removed in a procedure called fine needle aspiration biopsy (FNAB). The sample is then put on a slide so it can be examined by a pathologist under the microscope.
There are many conditions that can cause a thyroid nodule. Most thyroid nodules are non-cancerous growths that develop in a condition called nodular thyroid hyperplasia or nodular follicular disease. People with nodular thyroid hyperplasia usually have an enlarged thyroid gland with one or more nodules. This type of growth is also called a goiter. Non-cancerous tumours such as follicular adenoma and Hurthle cell adenoma can also cause thyroid nodules. These tumours are completely surrounded by a capsule that needs to be examined before a final diagnosis can be made. Cancerous tumours such as papillary thyroid carcinoma, follicular thyroid carcinoma, Hurthle cell carcinoma, and medullary thyroid carcinoma can also cause thyroid nodules.