[Objective] To investigate the value of ultrasound-guided fine needle aspiration cytology (FNAC) in the diagnosis of C-TIRADS4 thyroid nodules complicated with Hashimoto"s thyroiditis (HT).[Methods] A total of 1142 thyroid nodules (579 with HT and 563 without HT) who underwent FNAC in Rizhao Central Hospital from June 2020 to December 2023 were selected. All patients underwent two-dimensional ultrasonography indicating C-TIRADS4 thyroid nodules. The diagnostic performance of FNAC was compared between the HT(+) group and the HT(-) group.[Results] Among the 579 nodules in the HT(+) group, there were 77 cases (13.3%) of Bethesda class II, 162 cases (28.0%) of class III, 6 cases (1.0%) of class IV, 130 cases (22.5%) of class V, and 204 cases (35.2%) of class VI. Among the 563 nodules in the HT(-) group, there were 82 cases (14.6%) of class II, 101 cases (17.9%) of class III, 11 cases (2.0%) of class IV, 121 cases (21.5%) of class V, and 248 cases (44.0%) of class VI. The positive rate of thyroid nodule FNAC in the HT(+) group was significantly lower than that in the HT(-) group (P=0.006). The sensitivity, accuracy and specificity of FNAC in the HT(+) group were 78.6%, 81.5% and 95.4%. The sensitivity, accuracy and specificity of FNAC in the HT(-) group were 87.2%, 88.4% and 98.1%. The sensitivity and accuracy of FNAC in the HT(+) group were lower than those in the HT(-) group. The differences were statistically significant(P<0.05).[Conclusion] FNAC is an effective method for the diagnosis of thyroid nodules, and has high specificity in C-TIRADS4 thyroid nodules. however, the presence of HT reduces the sensitivity and accuracy of diagnosis. |