Thyroid and Parathyroid Conditions: Thyroid Nodules, Cysts, and Malignancies

Thyroid nodules are identified incidentally on imaging in most patients. Controversy exists on which patients warrant evaluation of an incidental thyroid nodule. If further assessment of a nodule detected on imaging or examination is pursued, thyroid ultrasonography with cervical lymph node survey and measurement of serum thyrotropin (TSH) may guide management decisions. When the TSH level is low, a nuclear medicine thyroid scan is necessary. Based on size, ultrasonographic features, and nuclear medicine results, patients with thyroid nodules may undergo ultrasonographic surveillance or biopsy with fine-needle aspiration. When fine-needle aspiration is performed, the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) provides a classification system for biopsy results. Molecular testing can be considered in the case of nodules with indeterminate findings based on biopsy. Malignant thyroid nodules and indeterminate nodules with suspicious molecular test results warrant surgical evaluation, whereas others may be monitored with periodic ultrasonography. Approximately 10% of nodules are clinically significant malignancies, and a small number of nodules cause compressive symptoms or progress to functional thyroid disease. Thyroid cancer overall has a 5-year survival of 98%.