[Role of ultrasonography-guided fine-needle biopsy in the selection for surgical treatment in thyroid diseases. Multicenter retrospective study of 5,109 patients].

: FNAB cytology is a very specific diagnostic tool for distinguishing benign from malignant lesions. It allows the histologic type to be diagnosed too. FNAB findings also help select the type of surgery. The value of FNAB cytology was investigated in 5,109 patients examined from 1987 through March 1993. 607 patients has surgical confirmation. 444 patients underwent cytology before surgery, while 163 patients were not submitted to FNAB. Histology diagnosed 116 malignant tumors (19.2%): 83 of them were papillary carcinomas (71.5%), 26 follicular carcinomas (2.6%), 1 primary thyroid lymphoma (0.9%) and 3 medullary carcinoma (2.6%). Seventy-nine of 116 cases had been diagnosed by FNAB cytology, while 37 of 116 were diagnosed at surgery. Aspiration biopsy under US guidance reduced the rate of thyroidectomies from 19.2% to 8.5% because true-positive cases were assessed before surgery. FNAB cytology should be used as a preliminary diagnostic tool, thanks to its high accuracy and to its capabilities of distinguishing benign from malignant lesions for proper medical or surgical treatment. Moreover, FNAB cytology allows potentially malignant lesions to be surgically explored.