Suspicious thyroid nodules with gradual size reduction: Ultrasound-pathology correlation by core needle biopsy specimen

초록

Purpose: To evaluate suspicious thyroid nodules with size reduction during the follow-up periods are malignancy or not. Methods: From November 2010 to July 2011, we enrolled 16 nodules of 16 patients (11 female and 5 male; mean age, 55 years) who had suspicious thyroid nodules, but showed size reduction (>30% decrease in maximum diameter) during the follow-up period (mean, 37 ± 27 months). All patients had suspicious thyroid nodules which showed previous nondiagnostic FNA readings and subsequently underwent US-guided CNB. US images were analyzed for internal content, shape, margin, echogenicity, presence of micro- and macro-calcification, inner isoechoic rim, and low-echoic halo. The histological features of CNB specimens were reviewed by one experienced pathologist. Results: All nodules had malignant US features at the time of CNB, but 7 of 16 (44%) nodules had malignant US features at initial FNA. Nine (56%) nodules were cystic or mixed cystic and solid on initial US. Inner isoechoic rim was present in 15 (94%), and low-echoic halo in 13 (81%). All nodules were confirmed to be a benignancy by CNB. 12 CNB specimens were available to pathologic analysis. The central portions were mainly composed of fibrosis (n=12, 100%), hemorrhage (n=8, 67%), atypia (n=1, 8%), and relatively few follicular cells in most cases. The peripheral portions had enough follicular cells in 11 cases. Two thyroid nodules were confirmed to be nodular hyperplasia and Hurthle cell adenoma by surgery. Conclusion: All thyroid nodules with suspicious US features with size reduction were benignancy and they were mainly composed of internal fibrosis and hemorrhage. CNB is helpful to diagnose and understand this unusual phenomenon as well as to prevent repeated FNA or surgery.