RESUMO
BACKGROUND: Fine-needle aspiration biopsy has been well established as a diagnostic technique for selecting patients with thyroid nodules for surgical treatment, thereby reducing the number of unnecessary surgical procedures in cases of non-malignant tumors. OBJECTIVES: To evaluate the sensitivity, specificity, accuracy, and positive and negative predictive values of FNAB in cases of a solitary thyroid nodule. METHODS: The preoperative FNAB results in 170 patients who underwent thyroidectomy due to a solitary thyroid nodule were compared retrospectively with the final postoperative pathologic diagnoses. RESULTS: In cases of a solitary thyroid nodule, FNAB had a sensitivity of 79%, specificity of 98.5%, accuracy of 87%, and positive and negative predictive values of 98.75% and 76.6% respectively. All cases of papillary carcinoma diagnosed by FNAB proved to be malignant on final histology, while 8 of 27 cases of follicular adenoma detected by preoperative FNAB were shown to be malignant on final evaluation of the surgical specimen. CONCLUSIONS: FNAB cytology reduces the incidence of thyroidectomy since this method has excellent specificity and sensitivity and a low rate of false-negative results. It proved to be cost-effective and is recommended as the first tool in the diagnostic workup in patients with thyroid nodules.
