Thyroid Nodules with Isolated Macrocalcifications:Malignancy Risk of Isolated Macrocalcifications andPostoperative Risk Stratification of Malignant TumorsManifesting as Isolated Macrocalcifications

ABSTRACT

Objective@#To determine the malignancy risk of isolated macrocalcifications (a calcified nodule with complete posterioracoustic shadowing) detected on ultrasonography (US) and to evaluate the postoperative American Thyroid Association (ATA)risk stratification of malignant tumors manifesting as isolated macrocalcifications. @*Materials and Methods@#A total of 3852 thyroid nodules (≥ 1 cm) of 3061 consecutive patients who had undergone biopsybetween January 2011 and June 2018 were included in this study. We assessed the prevalence, malignancy rate, and sizedistribution of isolated macrocalcifications and evaluated the histopathologic features and postoperative ATA risk stratificationof malignant tumors manifesting as isolated macrocalcifications. @*Results@#Isolated macrocalcifications were found in 38 (1.2%) of the 3061 patients. Final diagnosis was established in 30(78.9%) nodules; seven malignant tumors were diagnosed as papillary thyroid carcinomas (PTCs). The malignancy rate of theisolated macrocalcifications was 23.3% in the 30 nodules with final diagnoses and 18.4% in all nodules. Among the sixsurgically-treated malignant tumors, five (83.3%) had an extrathyroidal extension (ETE) (minor ETE 1, gross ETE 4), and two(33.3%) had macroscopic lymph node metastasis. Four (66.7%) malignant tumors were categorized as high-risk tumors, one asan intermediate-risk tumor, and one as a low-risk tumor using the ATA risk stratification. Histopathologically, out of the sixmalignant tumors, ossifications were noted in four (66.7%) and predominant calcifications in two (33.3%). @*Conclusion@#The US pattern of isolated macrocalcifications (≥ 1 cm) showed an intermediate malignancy risk (at least 18.4%).All malignant tumors were PTCs, and most showed an aggressive behavior and a high or intermediate postoperative ATA risk.