Usefulness of fine-needle aspiration in the diagnosis of thyroid carcinoma

BACKGROUND: Nodular thyroid disease is a frequent occurrence in clinical practice. The numerous diagnostic procedures available make the diagnosis of thyroid carcinoma possible but, if not used rationally, may lead to an unjustified increase in cost with little practical gain. The aim of the current study was to evaluate the usefulness of fine-needle aspiration (FNA) of palpable thyroid nodules after functional evaluation by thyroid scintigraphy. METHODS: The authors retrospectively evaluated 37,895 FNAs performed between 1980-1997. FNAs were performed on palpable thyroid nodules, except unambiguously autonomous ("hot") nodules, at the time of thyroid scintigraphy. Cytologic and histologic diagnoses were compared in 4069 patients to estimate the accuracy of FNA. RESULTS: The sensitivity of FNA was 91.8% and the specificity was 75.5%. A pretest probability of thyroid carcinoma of 4% was reduced to 0.4% in the patients with a cytologic diagnosis of benign nodular goiter, whereas it was increased to 90.7% in those patients with a positive cytologic diagnosis. Only in the case of a cytologic diagnosis of "follicular neoplasm" was the probability of malignancy not changed significantly and histologic evaluation of the nodule was necessary. CONCLUSIONS: In the majority of cases, FNA of palpable thyroid nodules allows for the identification of thyroid carcinoma and the planning of subsequent appropriate therapy. This can be achieved by using simple and inexpensive procedures, if cooperation among clinicians, pathologists, and nuclear physicians is maximized.