CORRELATION OF FINE-NEEDLE ASPIRATION CYTOLOGY AND FROZEN-SECTION BIOPSIES IN THE DIAGNOSIS OF THYROID-NODULES

Aims-To evaluate the correlation of fine needle aspiration (FNA) cytol ogy and frozen section biopsy in the diagnosis of thyroid nodules. Met hods-The medical records of 662 patients who underwent FNA cytology of the thyroid and thyroid surgery were analysed. Frozen section biopsie s were taken from 586 of the 662 patients. The diagnostic correlations of FNA cytology, frozen section, and both FNA cytology and frozen sec tion with definitive histological assessment were evaluated. Results-A mong the 662 patients who received FNA cytology, there were 356 cases (53.8%) diagnosed as benign, 114 cases (17.2%) as malignant, 148 cases (22.4%) as indeterminate, and 44 cases (6.6%) as unsatisfactory. The positive predictive value for the detection of malignancy by FNA cytol ogy was 92.1% and the negative predictive value was 95.2%. The inciden ce of malignancy in the indeterminate cytological diagnosis was 23%. T he diagnosis from frozen sections was benign in 445 cases (75.9%), mal ignant in 134 cases (22.9%), and deferred in 7 cases (1.2%). By frozen section, the positive and negative predictive values were 97% and 95. 5%, respectively. Diagnostic accuracy up to 98% was achieved when FNA cytology and frozen section diagnoses were in agreement. No false posi tives were observed when FNA cytology and frozen sections were both po sitive for malignancy. When FNA cytology and frozen section diagnoses were discordant, frozen section showed a higher accuracy (78.9%) than FNA cytology (21.1%). In the face of an indeterminate or unsatisfactor y cytological diagnosis, the diagnostic accuracy of frozen sections re ached 92.6%. Conclusions-The results confirm that FNA cytology is a us eful tool in the initial evaluation of thyroid nodules. Intraoperative frozen section is a valuable procedure to confirm the cytological dia gnosis and identify malignancy in patients with indeterminate or unsat isfactory cytological diagnosis. With reliance on frozen sections as a n intraoperative guide of thyroid surgery, the possibility of unnecess ary extensive surgery and the need for the second operation are consid erably lower.