Thyroid nodules are growths on the thyroid gland. They are the most common endocrine problem in the United States, especially in people who have a family history of thyroid disease. Most thyroid nodules do not cause any symptoms, but because 5-7% of thyroid nodules are malignant, it is important to have your thyroid examined.
It gets tricky, because it is difficult to detect nodules by touch or pressure; only about 5% of thyroid nodules can be felt, so many people are unaware they have them. The best diagnostic test is a thyroid ultrasound.
An ultrasound can show what the lesions look like, the size of the lesions, and their location within the thyroid gland. There are specific characteristics about the nodule that can be seen with an ultrasound machine including:
- If the lesion is solid, cystic (fluid-filled), or complex (both solid and cystic); hypoechoic, isoechoic, or hyperechoic; and
- If the lesion shows calcification, halo sign, or irregular shape or vascularity.
These features help the doctor assess risk for thyroid malignancy. The sonographic features associated with malignant nodules are: hypoechoic thyroid nodules, microcalcifications, irregular shape and margins, and intranodular vascularity.
Sonographic features associated with benign nodules are: hyperechoic thyroid nodules, macro or dense calcifications, cystic thyroid nodules, decreased size of nodule over time, and halo sign — a sonolucent rim around the nodule.
Ultrasound exams help decide if a nodule should have an FNA biopsy or ultimately surgical excision.