Fine needle aspiration cytology (FNAC) has become a standard diagnostic tool for thyroid nodules. The purpose of this study is to analyze the correlation between FNAC and the final histology to improve the diagnostic value.

We collected 792 patients who had undergone thyroidectomy, and we selected 549 patients who had undergone preoperative FNAC. The FNAC results were classified as non-diagnostic, malignancy, indeterminate and benign. The final pathologic reports were classified into two categories: malignant or benign. The individual histology was also identified. We retrospectively analyzed the pathologic result, the sensitivity, the specificity and the predictive value of the FNAC.

Among 549 patients, their FNACs showed 47 non diagnostic results, 189 malignancies,136 indeterminate results and 177 benign results. The false positive rate was 1.1% and the false negative rate was 12.9%. The final pathology reports were 262 malignancies and 287 benign lesions. There were 42 (30.9%) malignancies among the 136 indeterminate cases. Adenomatous hyperplasia was the most common benign lesion and papillary carcinoma (containing micropapillary carcinoma) was the most common benign lesion.

FNAC is an easy and safe diagnostic tool, but it still has many limitations. It is necessary to reduce the number of non diagnostic results. Technical advances, classification of the advanced categories of cytology and other staining methods can provide more specific results, and this can reduce the rate of performing unnecessary surgery.