Medical Evaluation
Thyroid cancer is often found in a routine physical examination when the doctor feels a painless lump in the neck. Both benign and malignant thyroid nodules can feel soft or firm, smooth or irregular when examined by the doctor. The doctor will order tests and perform some procedures to see if the nodule is benign or cancerous.
Ultrasonography is a painless and safe technique to view the thyroid nodule using sound waves to produce an image. The main use of thyroid ultrasound is to assess the nodule size, see whether it is solid or fluid-filled (cystic) and to guide placement of a needle for sampling fluid (fine needle aspiration biopsy).
A biopsy or fine needle aspiration (FNA) is necessary to determine if a nodule is benign or malignant. This procedure often requires the expertise of a cytopathologist, a doctor trained to obtain the specimen and to process and examine tissue for diagnosis. FNA results for certain thyroid cancers would be enough to determine if surgery (thyroidectomy) is necessary. However, FNA results that show "follicular cells" or "Hürthle cells" may be seen in both benign and malignant thyroid conditions. A biopsy is necessary to make the distinction by looking at more tissue under the microscope. The biopsy may be done as a "frozen section" during surgery, just prior to thyroidectomy.
Thyroid Nuclear (radionuclide) Scan. This is an imaging test to determine if a nodule is producing thyroid hormone or not. A small amount of radioactive material (Iodine-131 or I-131) is either swallowed or given intravenously. The thyroid gland takes up the radioactive chemical. An active nodule that produces thyroid hormone would pick up radioactive tracer and show up on X-ray film. Such an active (hot) nodule is usually a benign (non-cancerous) follicular or hyperplasic lesion. If little or no tracer is picked up, then the (cold) nodule is most likely cancer.
Patients with benign nodules are treated with thyroid hormone to suppress TSH. About 50 percent of these nodules will shrink. Malignant and "suspicious" nodules should be removed, as should "cold" nodules detected by radioactive Iodine-131 scanning.
More on Thyroid Cancer Needle Aspiration Biopsy
In the Encyclopedia:
Thyroid biopsy
Thyroid cancer
This article was reviewed and updated June 2007.
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