Suspicious thyroid nodules 4 cm require a diagnostic lobectomy regardless of their benign fine needle aspiration results

Background/objective: The diagnostic accuracy of fine needle aspiration biopsy (FNAB) seems limited in large thyroid nodules with Bethesda Cat. 2 result. We aimed to determine the incidence of carcinoma with benign cytology and the reason for the high false-positive rate in thyroid nodules >= 4 cm. Methods: The records of 103 patients with thyroid nodules >= 4 cm with preoperative cytological diagnosis of Bethesda Cat. 2 who underwent thyroidectomy were consecutively reviewed. Characteristics between patients with malignant vs. benign pathology were compared. Results: Forty patients (38.8%) had malignancy. Malignancy was subclassified into follicular variant of papillary thyroid carcinoma (43%), minimally invasive follicular thyroid carcinoma (20.0%), and minimally invasive Hurthle cell thyroid carcinoma (10.9%). Patients with malignant cytology had significantly more suspicious ultrasound findings than those with benign cytology (p = 0.001). Conclusions: Preoperative FNAB showed high false-negative rates in patients with thyroid nodules >= 4 cm with benign cytology. These nodules have a high malignancy rate with suspicious ultrasound findings. (C) 2021 Asian Surgical Association and Taiwan Robotic Surgery Association. Publishing services by Elsevier B.V.

Automated summary

Fine needle aspiration biopsy (FNAB) has limited diagnostic accuracy in large thyroid nodules with Bethesda Cat. 2 result. In nodules >= 4 cm, there is a high false-negative rate with benign cytology, and these nodules often have suspicious ultrasound findings with a high malignancy rate.