An introduction to benign thyroid disease: pathophysiologic, epidemiologic aspects and diagnostic methodology

The role of preoperative noninvasive diagnostic procedures in the management of benign thyroid diseases is critically reviewed and on the basis of a series of more than 13,000 thyroid nodules, sequentially examined, the role of preoperative fine needle aspiration (FNA) cytology in discriminating benign from malignant lesions, is assessed. Retrospective studies were performed to determine the diagnostic accuracy of FNA adopted as routine preoperative screening procedure as compared to intraoperative frozen section (FS) analysis. US-guided FNA was shown to be more accurate allowing the preoperative identification of occult or minimal carcinoma: in fact about 3% of malignant thyroid nodules were detected. Moreover, the operation time is reduced, and unnecessary surgical treatments for benign lesions are eliminated, preventing the need of two-stage cancer surgery. FNA is a cost-effective diagnostic tool with about 20% reduction in the cost of care of patients with thyroid nodules. Most recent methods of molecular biology which seem promising in thyroid tissue sampled by FNA to detect malignant lesions missed by conventional cytology and included in the generic category of "follicular proliferation", are analyzed.