Relative accuracy of fine-needle aspiration and frozen section in the diagnosis of well-differentiated thyroid cancer

The need for and extent of thyroid surgery for a thyroid nodule is usually primarily based on fine-needle aspiration (FNA) and frozen section diagnosis. The relative role of these modalities in 66 patients who had undergone FNA and subsequent thyroidectomy with frozen section was investigated. Cases that demonstrated discordance between FNA and frozen section (n = 22; 33%) were identified, and all slides were re-reviewed by a cytopathologist using current established cytologic criteria. A change in diagnosis was made in 13 cases with an increase in accuracy of FNA from 71% to 88%. The accuracy of frozen section (92%) did not change appreciably with re-review (94%). The accuracy of FNA and frozen section combined was found to be 98%. The rate of discordance decreased from 33% to 13% with re-review. When strict histologic and cytologic criteria are applied, FNA and frozen section are accurate and complementary methods that help in determining the operative management of thyroid masses. However, when FNA yields a diagnosis of “follicular neoplasm,” frozen section is unlikely to change this diagnosis.