The Combined Role of Ultrasound and Ultrasound Guided Fine-Needle Aspiration of Thyroid Nodules : The MDACC Experience

Thyroid nodules are a common problem found in up to two-thirds of the population on ultrasound examination. Nodules are often encountered incidentally on exams performed for other purposes. The prevalence increases with age and with radiation exposure and is higher amongst women. Approximately 5-15% of nodules are malignant; therefore, deciphering which nodules warrant attention is important. Factors that increase a nodules’ likelihood of being malignant include: history of radiation exposure, male patient, age over 45 years and family history amongst others (Table 1). A thyroid nodule is a discrete lesion seen within the thyroid gland that is distinct from the surrounding thyroid parenchyma. Thyroid nodules can be discovered on palpation or ultrasonographic examination or other imaging modalities (CT, MRI or FDG-PET scan etc). Nonpalpable nodules discovered by imaging modalities done for other purposes are often termed “incidentalomas”. Workup of Thyroid Nodules When the thyroid nodule is discovered, a complete history and physical examination should be performed. A pertinent history should include: history of thyroid disease, history of thyroid cancer or thyroid cancer syndromes (familial polyposis, cowden’s, carney’s, multiple endocrine neoplasias), and hoarseness. On physical exam, one should note the size of the thyroid and the nodules, associated lymphadenopathy, associated fixation of nodules to surrounding structures, signs of thyrotoxicosis and vocal cord paralysis. Laboratory and radionuclide investigation Once thyroid nodules are discovered, a serum TSH should be checked. If the serum TSH is suppressed, then a radionuclide thyroid scan is performed to determine if the nodule of interest is a “hot” nodule. Radionuclide scans include either technetium 99mTc pertechnetate scans or 123I scans. “Hot” nodules are indicative that the nodule is hyperfunctioning and tracer uptake is greater than the surrounding normal thyroid. Given that “hot” nodules rarely harbor malignancy, biopsy of these nodules is not usually warranted. Treatment for thyrotoxicosis should then ensue.