Fine needle aspiration biopsy of the thyroid gland: a study of 304 cases.

We discuss the interpretation of thyroid aspiration cytology in the light of our experience and review the circumstances in which false positives and false negatives may occur. The technique is reliable but by no means infallible and it should not be regarded as a final diagnostic work-up. Its value lies in selecting patients with thyroid nodules for surgery. In the present series of 304 patients, 79 underwent operation and 37 malignancies were found. The incidence of malignancy among the surgically excised nodules was 47%, in contrast to 14% in the past. We estimated that 268 operations would be required to salvage the same number of malignancies without the use of fine needle aspiration biopsy.