Once a nodule is discovered, the goal is to figure out whether the nodule is benign (not cancer) or malignant (cancer). The first step is to decide if the child has any increased risk of cancer by asking about their medical history, including exposure to radiation. It’s important to have a thorough physical exam of the thyroid and neck, to determine the firmness of the thyroid and nodule and to feel if there are abnormal lymph nodes in the neck. The next step is to check that the thyroid gland is producing normal amounts of thyroid hormone by checking levels of thyroid hormone (T4, thyroxine) and thyroid-stimulating hormone (TSH) in the blood.
It is not possible to know whether a nodule is cancerous or not just from the physical examination and blood tests. A thyroid ultrasound is needed and used to determine if a fine needle aspiration (FNA) biopsy should be performed.
Thyroid ultrasound (US) is the best tool to diagnose a thyroid nodule and to estimate the risk of cancer. US uses high-frequency sound waves to take a picture of the thyroid gland; it is not painful and does not use any radiation. This test tells doctors the size of the nodule and whether it is solid, fluid-filled (cystic), or a combination of both (partially solid and partially cystic). The images obtained of the thyroid gland and nodule can help identify nodules that look suspicious for cancer, but it cannot actually diagnose cancer. If a nodule looks like it could be cancerous, the next step is to perform an FNA biopsy of the nodule using a tiny needle (skinnier than a needle used for a blood draw). Ultrasound is often used to guide the needle directly into the nodule through the skin of the neck. The cells removed from the nodule are then examined by a specialist under a microscope to see if they look like cancer (see the FNAB nodules in children brochure to learn more about how this procedure is performed, as well as how to prepare for it).
In children with benign thyroid nodules, ultrasound is used in follow-up visits to see whether the nodule is growing or changing.
NUCLEAR THYROID SCANS:
Most children with thyroid nodules are producing normal amounts of thyroid hormone; however, if they are found to have a low TSH, the nodule itself may be making excess thyroid hormone (called an autonomously functioning thyroid nodule). The best test to see if the nodule is producing thyroid hormone is a thyroid nuclear scan. This test uses a tiny amount of radioactive iodine or technetium (also called radiocontrast): the nodule will absorb more of the radiocontrast if it is overactive (a ‘warm’ or ‘hot’ nodule). The radioactive iodine is either swallowed or the technetium is given intravenously. Most autonomous nodules are benign, but based on the US appearance, a FNA may be needed to confirm the diagnosis.