RESUMO
BACKGROUND: Preoperative and intraoperative diagnosis of follicular carcinoma (FC), resulting in one-stage surgical treatment of follicular thyroid tumors, is an important issue in thyroid surgery. METHODS: In the 10-year period there were 4158 operations performed on thyroid gland. There were 1559 patients with follicular tumors, 70 (4.4%) of them having FC. We analyzed the groups of patients with FC determined on frozen section (FS) and permanent section (PS) according to duration of clinical symptoms, ultrasound (US) examination, tumor size, patient gender and age, intensity of invasion, localization, and multiple or solitary occurrence of tumor. RESULTS: FC was diagnosed in 39 (55.7%) patients on frozen section (FS). Among the encapsulated (minimal invasion) carcinomas, the FS was accurate in 19 of 33 (57.6%) FC and in 5 of 15 (27.8%) Hürthle cell carcinomas (HCC); among extensively invasive carcinoma in 11 of 14 (78.6%) FC and in 4 of 5 (80.0%) HCC. FC was significantly more common in men (p <.001) and in the right lobe (p <.05). We did not find statistically significant differences concerning duration of symptoms, US examination, tumor size, patient age, and multiple or solitary occurrence of the tumor between the patients with FC diagnosed on FS and the patients with FC diagnosed on PS. CONCLUSIONS: The intraoperative diagnosis of FC is difficult. Although the percentage of false-negative results was relatively high (44.3%), there were no false-positive results. This means that the second operation was avoided in 55.7% of the patients, and no unnecessary thyroidectomies were performed. FS biopsy is an important method in surgery of follicular tumors. Improved technical support and the ability to analyze a greater number of slides will increase the accuracy of the method.