[Diagnostic strategy for a thyroid nodule]

Solitary thyroid nodules present as localized tumefactions of the thyroid gland readily detectable clinically. They are frequent (2-5% of the general population) and due to a variety of causes, each requiring a specific treatment; hence the need for a systematized diagnostic approach. On scintigraphic grounds, one can distinguish between "warm" or "extinctive" nodules (10% and 20% of the cases respectively), which are a priori benign, and "cold" nodules (70%), which in 1 out of 10 cases correspond to a differentiated epithelioma with excellent post-operative prognosis. Three methodological data call for comments: (1) the images supplied by technetium may differ from those supplied by radioactive iodine, which remains the reference radioisotope; (2) there is no clinical criterion of malignancy, but fluid-containing nodules are almost invariably benign; (3) needle cytology is the best means of selecting nodules for surgery and histology which is the only reliable diagnostic examination. We therefore propose, albeit with due caution, a diagnostic approach based on the sequence scintigraphy-needle exploration and cytology and aimed at limiting surgery to purely therapeutic purposes.