Malignancy Risk Stratification of Thyroid Nodules with Macrocalcification and Rim Calcification Based on Ultrasound Patterns

Abstract

Objective: To determine the association of macrocalcification and rim calcification with malignancy and to stratify the malignancy risk of thyroid nodules with macrocalcification and rim calcification based on ultrasound (US) patterns.

Materials and methods: The study included a total of 3603 consecutive nodules (≥ 1 cm) with final diagnoses. The associations of macrocalcification and rim calcification with malignancy and malignancy risk of the nodules were assessed overall and in subgroups based on the US patterns of the nodules. The malignancy risk of the thyroid nodules was categorized as high (> 50%), intermediate (upper-intermediate: > 30%, ≤ 50%; lower-intermediate: > 10%, ≤ 30%), and low (≤ 10%).

Results: Macrocalcification was independently associated with malignancy in all nodules and solid hypoechoic (SH) nodules (p < 0.001). Rim calcification was not associated with malignancy in all nodules (p = 0.802); however, it was independently associated with malignancy in partially cystic or isoechoic and hyperechoic (PCIH) nodules (p = 0.010). The malignancy risks of nodules with macrocalcification were classified as upper-intermediate and high in SH nodules, and as low and lower-intermediate in PCIH nodules based on suspicious US features. The malignancy risks of nodules with rim calcification were stratified as low and lower-intermediate based on suspicious US features.

Conclusion: Macrocalcification increased the malignancy risk in all and SH nodules with or without suspicious US features, with low to high malignancy risks depending on the US patterns. Rim calcification increased the malignancy risk in PCIH nodules, with low and lower-intermediate malignancy risks based on suspicious US features. However, the role of rim calcification in risk stratification of thyroid nodules remains uncertain.

Keywords: Calcification; Data systems; Risk assessment; Thyroid nodule; Ultrasonography.

Conflict of interest statement

The authors have no potential conflicts of interest to disclose.

Copyright © 2021 The Korean Society of Radiology.

Figures

Fig. 1. Flow diagram of patient enrollment. CNB = core needle biopsy, FNA = fine-needle aspiration, US = ultrasound

Fig. 2. A 55-year-old woman with a 1.2-cm right thyroid lobe nodule.

The ultrasound image shows solid hypoechoic nodule with macrocalcification with posterior shadowing (arrow). A final diagnosis of conventional papillary carcinoma was established based on surgical pathology findings.

Fig. 3. A 48-year-old woman with a 2.7-cm left thyroid lobe nodule.

The ultrasound image shows a solid, predominantly isoechoic nodule with incomplete rim calcification (short arrows) and a microcalcification (punctate echogenic foci) (long arrow). A final diagnosis of minimally invasive follicular thyroid carcinoma was established based on surgical pathology findings.

Fig. 4. A 63-year-old woman with a 2.0-cm left thyroid lobe nodule.

The ultrasound image shows a solid hypoechoic nodule with incomplete rim calcification (short arrows) and suspicious ultrasound features of nonparallel orientation (taller than wide) and microcalcification (punctate echogenic foci) (long arrow), as well as multiple large echogenic foci. Findings from repeated ultrasound-guided fine-needle aspirations were nondiagnostic and core needle biopsy revealed benign follicular nodule with degeneration. A follow-up ultrasound performed 9 years after the initial fine-needle aspiration showed no change in the size of the nodule.