Fine-needle aspiration cytology and frozen section examination in pre- and intraoperative diagnosis of thyroid cancer

In contrast to thyroid nodules thyroid cancer is a rare condition, which requires an early diagnosis and treatment. Patients with nontoxic solitary thyroid nodules (NSTN) both fine-needle aspiration cytology (FNAC) and intraoperative frozen-section examination (IFSE) are usually requested for the adequate surgical planning. The aim of this study was to evaluate the usefulness of FNAC and IFSE in patients with NSTN undergoing surgery. We retrospectively analyzed a series of 606 patients with a SNTN who underwent both preoperative FNAC and IFSE prior to partial or total thyroidectomy. There were 118 (19.5%) men and 488 (80.5%) women, with an overall median age of 44 years (range 16-81 years). Final pathologic examination showed 500 (82.5%) benign nodules, including 239 (39.4%) follicular adenomas, and 106 (17.5%) thyroid carcinomas, of which 80 (75.5%) papillary, 18 (17.0%) follicular, 5 (4.7%) undifferentiated, and 3 (2.8%) medullary carcinomas. Patients with benign tumors were significantly (p=0.002) younger. In the preoperative differential diagnosis between hyperplastic thyroid nodules and thyroid tumors, sensitivity, specificity, positive predictive value (PPV), negative-predictive value (NPV) of FNAC were 93.6%, 98.9%, 92.1%, 99.4% and 95.9%, respectively. In the detection of malignancy sensitivity, specificity, specificity, PPV, NPV, and accuracy were 94.3%, 99.8%, 98.8%, 99.0%, and 98.8% for FNAC, and 95.3%, 99.0%, 100%. and 99.2% for IFSE (p=NS, chi-squared test). The combination of FNAC and IFSE did not improve significantly (p=NS) the results. In fact, IFSE suggested a thyroid cancer in only one of the 6 patients with false negative FNAC, and failed to detect malignancy in 5 of 18 (27.8%) follicular carcinomas. In conclusions, in patients with NSTN and an adequate FNAC suggesting malignancy IFSE may be unnecessary, land in those with follicular tumors the results of both FNAC and IFSE should not affect the final intraoperative decision-making.