Traditionally the extent of thyroidectomy in patients with nodular thyroid disease has been based on fine needle aspiration cytology and intraoperative frozen section examination. The value of routine frozen section examination for intraoperative diagnosis of thyroid cancer and determination of extent of thyroidectomy is controversial and needs to be evaluated.

We reviewed the fine needle aspiration cytology, frozen section examination, and final pathology of 142 consecutive patients who underwent thyroidectomy for nodular thyroid mass in an 3-year period. The diagnosis were classified as indeterminant, benign, or malignant. The utility and impact of the diagnosis from fine needle aspiration or frozen section on the operative procedure performed was analyzed.

Fine needle aspiration cytology (FNA) as a diagnostic test for thyroid nodules demonstrated an indeterminant rate of 23.9% (34 patients), with diagnostic accuracy of 93.9% for malignant disease. In frozen section (FS) results, the indeterminant rate was 19.7%, and the diagnostic accuracy 98.3% for malignant disease. Of the 50 patients with the benign results on FNA, 3 patients was diagnosed as malignancy on FS. Of the 34 patients with indeterminant results on FNA, the intraoperative FS diagnosis showed 16 patients of benign, 3 patients of malignancy, and diagnosis on 15 patients was deferred to permanent section; in 15 patients, benign disease was diagnosed in 12 patients, and 3 patients were diagnosed as malignancy. And one of 10 patients with inadequate result on FNA was diagnosed as malignancy on FS. Therefore the decision about the extent of surgical thyroid resection was changed in 7 patients (4.9%) based on the FS results, and including the 16 patients diagnosed as benign on FS with indeterminant results on FNA, overall, in 23 patients (16.2%) the intraoperative surgical decision was affected by FS.

The fine needle aspiration cytology and intraoperative frozen section examination showed the limitation on diagnosis of follicular neoplasm, but intraoperative frozen section examination proved useful in determining the extent of operation and affected intraoperative decision making in thyroid surgery.