Cytopathological findings from fine-needle aspiration biopsy are accurate predictors of thyroid pathology in patients with functioning thyroid nodules.

The cytopathological findings after fine-needle aspiration biopsy (FNAB) of functioning solitary thyroid nodules (FSTN) are not well defined. This is an important issue, once this procedure is the first step in nodule evaluation. This study evaluated FNAB findings and correlated these findings with histopathology in patients subjected to thyroidectomy. Eleven clinically euthyroid female patients (age range: 19 to 47 years) with FSTN, satisfactory specimens from FNAB and negative antithyroid antibodies were studied. Seven patients had autonomous nodules. The cytopathological findings were of follicular pattern suggestive of neoplasia in one case where the histopathological examination confirmed a follicular adenoma. In all other 6 autonomous cases, the smears were suggestive of colloid goiter and they had surgery due to compressive symptoms (n=4) or subclinical hyperthyroidism (n=2). The histopathological results confirmed colloid goiter in all except one who presented a follicular adenoma. Four patients had functioning thyroid nodules that suppressed their 1311 uptake after receiving T3. The cytopathological findings were considered malignant in one case surgically confirmed to be a papillary carcinoma. In all other 3 non-autonomous cases, the smears were suggestive of colloid goiter and they had surgery due to compressive symptoms (n=1), aesthetic reasons (n=11) or increase in nodule volume (n=1). The histopathological results confirmed colloid goiter. In conclusion, FNAB was an accurate predictor of thyroid pathology in FSTN without false-positive results in the present study.