Accuracy of fine‐needle aspiration cytopathology to differentiate malignant and benign thyroid nodules with ≥4 cm diameter: A retrospective study

Abstract Background Thyroid nodules (TN) are commonly present in the general population and are usually pathologically benign. An initial diagnosis with fine‐needle aspiration (FNA) cytopathology could help clinical decision‐making with fewer complications. As the previous studies suggest surgical procedures for >4 cm TNs, we aimed to investigate the accuracy of preoperative FNA cytology to predict malignancy risk in these nodules in a sample of the Iranian population. Methods Patients with ≥4 cm TNs who had preoperative FNA cytology, underwent nodulectomy and had a histopathological report were included. Each patient's preoperative demographic, ultrasonographic, and cytology data were gathered. After surgery, resected samples were assessed pathologically and diagnosed as benign or malignant. Finally, data were analyzed to evaluate the presurgical accuracy of the FNA cytology. Results We identified 41 (51.25%) patients with malignant legions among our study population ( N = 80). The pathology reports were indeterminate in 3 patients with follicular neoplasm. Bethesda scores were substantially higher in patients with malignancy. The sensitivity, specificity, and false‐negative rate of FNA cytology reports using the Bethesda system were 73.7%, 74.2%, and 26.3%, respectively. There was no association between malignancy and TNs' size, neither their volume nor their highest diameter. Conclusion FNA cytology is not as sensitive and specific in nodules>4 cm as in smaller ones. However, it can still be used alongside other diagnostic procedures in malignancy screening. Clinicians should make more complex decisions considering various influential factors to avoid missing malignant lesions and reduce diverse probable complications of highly invasive diagnostic surgery. Further prospective research on >4 cm TNs and their multiple features' association with malignancy is required for more precise judgment.