Expanding role of fine-needle aspiration cytology in thyroid diagnosis and management.

In non-iodine-deficient areas, 4% to 7% of the population are reported to have thyroid abnormalities. Prophylactic operations of these nodules in the thyroid are not indicated and not cost-effective, as at least four of five nodules are colloid goiter and only a few are malignant. The need for a reliable preoperative diagnosis is great, and fine-needle aspiration (FNA) is now considered the first choice during workup for thyroid nodules. The steps in the FNA procedure are clinical examination and localization of the target lesion, aspiration, preparation of smears, and collecting material for ancillary microscopy techniques. All these steps must be exercised to allow optimal use of FNA. It can also be combined with various other methods, such as immunohistochemistry of thyroglobulin and calcitonin, analysis of nuclear DNA, DNA preparation for molecular biology analyses, and magnetic resonance spectra. The accuracy of the clinical routine in our unit was evaluated by studying the 5-year outcomes of almost 4000 FNAs of the thyroid. The results were good, with only a few false-negative and false-positive results; but the problem of differentiating follicular adenoma from follicular carcinoma remains a significant problem. It is now well established that FNA biopsy and cytology is the best modality available for the workup of thyroid nodules and is widely utilized in endocrine surgical centers worldwide.