[The "cold" nodule of the thyroid gland: 20 years experience with 2,071 patients and diagnostic limits of fine needle biopsy].

The files of 2071 patients with (Tc99m)-scintigraphically "cold" thyroid nodules (CTN) attending a teaching hospital were analysed retrospectively. Between 1975 and 1995 altogether 49 endocrinologists with varying degrees of experience carried out the clinical evaluation as well as fine needle aspiration biopsy (FNAB), and 33 pathologists undertook the cytological interpretation. By clinical criteria the CTN of 1272 patients were deemed benign, whilst malignancy was suspected in 301 patients (81% and 19% of evaluable cases, respectively). A cytological diagnosis was made in 47.3% of all FNAB performed ("benign" in 611 patients, "follicular neoplasia" in 86, and "malignant" in 39 patients; 39.3%, 5.5% and 2.5%, respectively). 36.5% of the clinically suspect CTN and all nodules with a cytological diagnosis of either "follicular neoplasia" or "malignant" in patients who could be followed up after the FNAB procedure were treated surgically, leading to a total of 420 histological diagnoses. 76% and 35% of the CTN classified as being suspicious of malignancy in the preoperative clinical and cytological evaluation, respectively, were found to be malignant on histology. A clinical assessment of "no abnormality" and "normal" cytology missed a malignant lesion in 16.3% and 15% of cases, respectively. Thus, under routine teaching hospital conditions, the selection of patients with CTN for surgery cannot be based on cytological criteria alone. The FNAB in this setting should be employed exclusively to supplement the clinical and scintigraphically findings.