False-negatives in thyroid nodule aspiration cytology.

To the Editor—We congratulate Cheung et al1 for providing local data on the accuracy of fine-needle aspiration cytology (FNAC) of non-toxic thyroid nodules. In 2003, we retrospectively analysed the results of 192 FNAC of thyroid nodules performed in Queen Elizabeth Hospital between January and June 2001. Forty-three of those patients underwent thyroidectomy and a comparison of the histopathological findings with the FNAC results yielded false-positive and false-negative rates of 0% and 5% respectively, similar to Cheung et al’s series. As in their series, the retrospective nature of our analysis precluded prospective monitoring of thyroid nodule growth. The false negative rate could be an underestimation, since our mean follow-up period was only 24 months after FNAC.