Fine-needle aspiration biopsy of the thyroid. The problem of suspicious cytologic findings.

Cases in which thyroid nodules yielded suspicious cytologic findings on fine-needle aspiration biopsy were prospectively studied during a 3-year period. Of 1970 patients, 333 (17%) had suspicious cytologic findings; from this group, the cases of 253 patients were studied. The cytologic diagnoses were 96 (38%) H urthle cell neoplasms, 84 (33%) follicular cell neoplasms, and 73 (29%) nonspecific diagnoses. A thyroid scan was obtained in 123 of 203 (61%) patients with a solitary nodule, and the nodules were hypofunctional in 102 (83%). Malignant lesions were found in 60 (24%) of the 253 patients. Our findings are consistent with reports that 20% of patients who have a fine-needle aspiration biopsy will have suspicious cytologic findings and that of these, 20% may have a malignant lesion. Thyroid scanning will not distinguish between benign and malignant thyroid lesions that are suspicious on cytologic examination. Surgical excision of all suspicious lesions seems reasonable.