What are the keys to successful thyroid FNA interpretation?

There is much concern expressed in the literature regarding the lack of predictive power of the thyroid fine needle aspiration/ biopsy (TFNAB) approach to defining the nature of clinically detected thyroid nodules. This has been exacerbated in the past decade or more by the routine use of ultrasonography (US) in examining the thyroid as well as the introduction of molecular testing in the realm of thyroid pathology. Some have even gone so far as to suggest replacing the TFNAB with molecular signature testing to reduce the degree of uncertainty for a specific cytological diagnosis. This review addresses those concerns with a re-emphasis on understanding the basic keys to successfully evaluating a patient with a thyroid nodule by routine TFNAB examination. These keys include bringing to bear an experienced group of physicians in an integrated team approach, a sharpened focus on the TFNAB cytological categories and a grounded understanding of the predictive ability of molecular testing in a given patient when the cytological interpretation creates too much uncertainty in the minds of the patients and clinicians in attempting to reach a decision on how to manage a thyroid nodule. With this practical approach in mind, the false-negative and false-positive rates of "negative (benign)" and "positive (malignant)" thyroid aspirates should be no more than 1%; and the prevalence of an "indeterminate" aspirate - the area in TFNAB attracting the most attention for improvement with novel biomarkers - should be 10% or less. Thus, physicians should be capable of managing at least 90% of patients undergoing TFNAB in a confident manner without further testing beyond the routine, future re-examination of the patient's nodule to re-assess for any change in its nature or its impact on the patient's quality of life. The other 10% can then be considered for molecular testing in a manner tailored to those individuals truly in need of a more sophisticated - and expensive - approach to the characterization of their thyroid nodules. As the era of US has matured - just as with the era of serum PSA testing for prostate cancer in men - we have experienced a paradigm shift: Given the incidence of thyroid nodules in the U.S. adult population in comparison with the risk of dying of thyroid malignancy, the main role of TFNAB is to reduce the need for surgical intervention.