The thyroid nodule.

The various techniques for evaluating a thyroid nodule are described and their relative values analyzed. Fine-needle aspiration is the most sensitive and specific test among the leading techniques, the others being ultrasonography and thyroid scanning. A combination of tests is also analyzed. In Plan A, a scan is followed by a fine-needle aspiration; in plan B a scan is followed by thyroid ultrasound; and in Plan C, fine-needle aspiration is followed by a scan only in those subjects with cytologically suspicious lesions. Of the three plans, Plan C is superior from the standpoint of diagnostic accuracy and cost effectiveness. Improvement of existing tests or the addition of new tests for evaluating thyroid nodules will aid in distinguishing between benign and malignant thyroid nodules.