Ultrasonographic Evaluation of Pediatric Thyroid Nodules: Adult Risk Stratification Systems, 2021 K-TIRADS Revision, and Future Refinements.

Although pediatric thyroid cancer is rare, it has characteristics distinct from those of adult thyroid cancer. Thyroid nodules in children present a higher risk of malignancy, more frequent lymph node and distant metastases, and distinct molecular profiles compared to adults. Despite a more aggressive initial presentation, the long-term prognosis for children is excellent, with paradoxically low mortality rates, even in patients with distant metastases. Therefore, it is questionable whether ultrasound-based risk-stratification systems primarily developed for adults can be directly applied to children. The 2021 Korean Thyroid Imaging Reporting and Data System (K-TIRADS) introduced pediatric-specific biopsy cut-offs and risk-adapted considerations, improving sensitivity, specificity, and overall accuracy. Nevertheless, challenges remain in achieving better diagnostic performance. Specific considerations must also be noted when evaluating pediatric thyroid nodules, such as the diffuse sclerosing subtype of papillary thyroid cancer and intrathyroidal ectopic thymus. Overdiagnosis and age-related heterogeneity further complicate risk assessment and management. Future guidelines could adopt stratified approaches based on patient age and sonographic mimickers, with additional integration of molecular profiling and artificial intelligence-assisted decision support. This review summarizes the current state of ultrasonographic evaluation of pediatric thyroid nodules, including the 2021 K-TIRADS, and discusses future refinements for pediatric-specific ultrasound risk-stratification systems.