Fine-needle aspiration (FNA) is the most effective diagnostic means in the management of nodular thyroid disease. Therefore, we decided to evaluate the diagnostic reproducibility of FNA and the usefulness of repeated FNA in benign nodular thyroid disease. We evaluated 799 satisfactory aspirations performed in 306 patients (298 females) aged 14-84 years, followed for 2-12 years. FNAs were performed on an annual basis. Of all patients, 299 (97.71%) maintained benignity: 230 (75.16%) repeated the same cytologic pattern, and 69 (22.54%) showed diagnostic variations within benign pathologies. In 3 patients (0.98%) the diagnosis changed to suspicious and in 4 (1.30%) to papillary carcinoma in the whole group. Of these 4 cases, 1 was diagnosed in the second (0.57%) and 3 in the third repeat FNA (2.25%). In 6 cases in which increased nodular size was observed, no change to malignancy was detected, while 3 of the carcinomas found showed no changes in size.
In conclusion: (1) The variation in cytologic diagnoses within benign pathologies can be attributed to the coexistence of nonuniform pathologies. Aspirations performed in different sites of the nodule would contribute to obtain a more representative specimen. (2) In the absence of suspicious clinical changes and with at least three FNAs confirming the cytologic diagnosis of benignity, the follow-up of nodules by FNA could be discontinued and (3) In our experience, the diagnostic change from benign to malignant after three repeat FNAs appears to indicate that it would be advisable to perform three procedures.