FNA Cytology and Frozen Section Examination in Patients with Follicular Lesions of the Thyroid Gland

Patients with solitary thyroid nodules should have fine-needle aspiration (FNA) cytology as the initial screening test, but the most of those referred to a surgeon usually undergo frozen section examination (FS). The aim of this retrospective study was to assess the usefulness of FNA cytology and FS together in patients with a solitary thyroid nodule (TN). Two-hundred and ten patients with a TN and FNA cytology suggesting follicular neoplasm underwent intraoperative FS and subsequent hemithyroidectomy or total thyroidectomy. There were 47 (22.4%) men and 163 (77.6%) women, with a median age of 43 years (range 18-76 years). In all patients, ultrasound-guided FNA was successfully performed using 22-G needle prior to surgery. Smears of the FNA samples were stained by May-Grünwald-Giemsa stain and evaluated immediately by the cytologist. Final histology was follicular carcinoma in 23 (10.9%), follicular adenoma in 181 (86.2%), and hyperplasia in 6 (2.9%) patients. No difference (p=NS) in age of the patients, and greatest diameter on the TN was found between groups. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 13.0%, 97.3%, 37.5%, 90.0%, and 88.1% for FNA cytology, and 17.4%, 100%, 100%, 90.8%, and 91.0% for FS, respectively. The combination of FNA plus FS did not significantly improve the results. In conclusion, both FNA cytology and FS are highly specific tests, but their sensitivity is low, even when they are used in combination. Thus, in patients with smears suggesting follicular neoplasm, FS should be considered unnecessary because it does not affect the intraoperative decision making. FS is most useful in those cases that are diagnosed as suspicious for papillary carcinoma by FNA.