Fine needle aspiration biopsy in the diagnosis of thyroid nodules

The fine needle aspiration (FNA) biopsies performed on thyroid nodules at Turku University Central Hospital from 1983 to 1988 were reviewed. Of the 1,054 total aspirated nodules, 194 were investigated histologically after thyroid surgery (191 cases) or at autopsy (3 cases). Two cases with an insufficient FNA sample, 4 with an incidental occult papillary carcinoma and 2 cases with carcinoma outside the nodule investigated by FNA biopsy were excluded from the series, leaving 186 histologically confirmed nodules in the final analysis. Three (3%) of the 107 cases with an FNA biopsy diagnosis of benign, 4 (8%) of the 52 with an FNA diagnosis of equivocal, 3 (20%) of the 15 with an FNA diagnosis of suspicious and all 12 (100%) with an FNA diagnosis of malignant were histologically malignant. If only an unequivocally malignant cytologic finding is considered positive, FNA biopsy had a diagnostic specificity of 100%, a sensitivity of 55% and an accuracy of 95% among the histologically confirmed cases. Follow-up revealed no cases of cancer among the 863 thyroids that were not explored surgically. It is concluded that FNA biopsy is a practical method with considerable diagnostic value in the evaluation of thyroid nodules.