[The thyroid nodule. Diagnostic considerations].

Thyroid nodule is extremely common. Its prevalence has been estimated to be more than 5% in the adult population. If thyroid nodule is a rare condition, 0.004% a year, identifying those nodules, which are likely to be malignant, is very important for physicians. The evaluation of thyroid is carried out using the fine needle aspiration biopsy (FNAB), the ultrasonography, and scanning with 131I and 99Tc. Before FNAB thyroid scans was the most common test in clinical evaluation of thyroid nodules, used to identify "hot" and "cold" lesions. Hot or warm nodules, about 5%, are seldom malignant, whereas cold or hypofunctional have a 10% to 25% chances of being malignant. FNAB is the elected laboratory test: this procedure is easily, simple, non traumatic, and very acceptable to the patients. Ultrasound is useful in several settings: it provides a non invasive and relatively inexpensive means of following the size of nodule, after medical therapy and FNAB.