Approach to the Patient with a Cytologically Indeterminate Thyroid Nodule

Background: Fine-needle aspiration remains the primary diagnostic intervention for the evaluation of most thyroid nodules larger than 1-1.5 cm. Although most aspirates provide diagnostic cytology, approximately 15-25% will be classified indeterminate (often referred to as follicular neoplasm, suspicious for carcinoma, or atypical). In such cases, abnormal cellular findings preclude interpretation of benignity, although only a minority will prove cancerous upon final histopathology. Nonetheless, patients with indeterminate aspirates are commonly referred for consideration of hemi- or near-total thyroidectomy. Recently, improved understanding and novel investigation of clinical, radiological, cytological, and molecular factors has allowed improved stratification of cancer risk. Conclusion: Although surgery continues to be commonly recommended, strategies for such patients should increasingly seek to define treatment based on the estimation of an individual's thyroid cancer risk in comparison with associated operative risk and morbidity. In doing so, the rate of unnecessary surgical procedures and associated complications can be reduced. (J Clin Endocrinol Metab 93: 4175-4182, 2008)