Accuracy and significance of fine-needle aspiration and frozen section in determining the extent of thyroid resection.

The records of 46 patients were retrospectively reviewed to determine the accuracy and significance of fine-needle aspiration (FNA) and intraoperative frozen section (FS) in planning the extent of thyroid resection. For all 46 patients, both FNA and FS diagnoses were available for comparison with the final pathologic diagnosis. The sensitivity value for detection of malignancy by means of FNA was 90% compared with 60% by means of FS, although FS diagnoses were more specific (97%) than FNA diagnoses (56%). FNA diagnoses of benign conditions were correct in 20 of 21 (95%) patients. FS diagnoses of benign conditions were correct in 19 of these 21 patients (90%) but, more important, it did not alter the extent of resection or improve the accuracy of diagnosis. Five patients had findings at FNAs that were positive for malignancy. Frozen section confirmed this diagnosis in all five patients but, again, did not alter the extent of resection. Twenty patients had FNA findings that were "suspicious" for malignancy, with 12 of the tumors diagnosed as benign on FS and only one of four (25%) papillary carcinomas diagnosed as positive on FS. Only four of 20 (20%) FNA results that were "suspicious"--but not diagnosed as malignant--were confirmed as malignant on permanent section, whereas 70% of the FS diagnoses were correct in these 20 patients. Overall, only 16 of 46 (35%) FS diagnoses were helpful in determining the extent of thyroid resection. If a diagnosis of a benign or definitely malignant condition has been made by means of FNA preoperatively, FNA alone provides sufficient information for determining the extent of thyroid resection. Frozen section may be helpful if FNA results are suspicious, but it does not have sufficient sensitivity for determining the extent of resection, which should be deferred until permanent sections have been analyzed.