A thyroid nodule is a lump or growth in the thyroid gland. It can be noticed on routine physical examination, on imaging studies for another problem or frequently felt by the patient.
Thyroid nodules are very common. Up to half of all people have at least one thyroid nodule, although most do not know about it.
Thyroid nodules may arise from benign or malignant cells which have grown large enough to be noticed. Occasionally, a thyroid nodule is cystic (fluid filled sac) which is reassuring and rarely will have cancer. Many times thyroids have multiple nodules in a condition called Multinodular Goiter. In this case, frequent monitoring of the nodules is important to determine their growth patterns. A dominant nodule that is growing may require a fine needle biopsy.
Reassuringly, about 95 percent of all thyroid nodules are caused by benign (non-cancerous) conditions.
Diagnostic tests can determine if a thyroid nodule is benign or malignant (cancerous). Blood tests for Thyroid Stimulating Hormone (TSH) are frequently done to determine if the thyroid is overactive or underactive but usually do not help in determining the nature of the nodule.
- Thyroid ultrasound — A thyroid ultrasound should be performed in all patients with a suspected thyroid nodule or nodular goiter. Thyroid ultrasonography is used to answer questions about the size and anatomy of the thyroid gland and nearby structures in the neck. Thyroid ultrasound findings can be used to select nodules that require fine needle aspiration (FNA) biopsy.
- Fine needle aspiration — In most cases, the TSH level is normal, and the next step is the fine needle aspiration (FNA). FNA uses a thin needle to remove small tissue samples from the thyroid nodule. The tissue is examined with a microscope.
- This test is accurate in identifying cancer in a suspicious thyroid nodule. In some cases, the biopsy does not contain enough tissue to make a diagnosis, and a repeat biopsy is necessary. In other cases (10 percent), the result of the biopsy is indeterminate. Surgery is frequently recommended for indeterminate nodules for a definite diagnosis.
- Thyroid scan — Most people do not have to have a thyroid scan – only those who have a low TSH level. In these cases, the thyroid scan is the first step after the blood test (instead of the fine needle aspiration).
Thyroid Nodule Treatment
The appropriate thyroid nodule treatment depends upon the type of thyroid nodule that is found
- Benign thyroid nodules — Benign thyroid nodules usually develop as a result of overgrowth of normal thyroid tissue. Surgery is not usually recommended, and the thyroid nodule can be monitored over time. If the thyroid nodule grows, a repeat biopsy or surgery may be recommended. Some surgeons recommend excision of nodules over 4 cm.
- Indeterminant or suspicious nodules may require observation or surgery depending on the risk of malignancy based on the characteristics of the cells under the microscope, the size and appearance on ultrasound, and risk factors associated with each patient. In these cases, discuss with your surgeon whether or not surgery is right for you.
- Malignant thyroid nodules (thyroid cancer) — Only about 5 percent of all thyroid nodules are malignant. Most patients with thyroid cancer have an excellent chance for cure or long-term survival.
- The treatment of thyroid cancer will depend on the type of cancer. Thyroid cancers require surgical removal of the thyroid gland and sometimes one or more treatments with radioactive iodine, followed by thyroid hormone (T4) suppressive therapy.