Ultrasound classification of thyroid nodules: does size matter?

Area of Science:

• Endocrinology
• Radiology
• Cytopathology

Background:

• Thyroid nodules are common, and ultrasound-guided assessment is crucial for risk stratification.
• The American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS) categorizes nodules based on ultrasound features.
• The Bethesda System for Reporting Thyroid Cytopathology classifies fine needle aspiration (FNA) biopsy results.

Purpose of the Study:

• To investigate the correlation between thyroid nodule size and Bethesda cytopathology classification.
• To assess the utility of nodule size in guiding FNA biopsy decisions for ACR-TIRADS categories 3 and 4.

Main Methods:

• A retrospective analysis of 566 thyroid nodules classified as ACR-TIRADS 3 or 4.
• Nodules were stratified into three size categories based on American Thyroid Association guidelines.
• Frequency analysis of Bethesda categories within each size and ACR-TIRADS classification.

Main Results:

• The majority of nodules in both ACR-TIRADS categories were Bethesda 2, irrespective of size.
• ACR-TIRADS 4 nodules showed a significantly higher prevalence of Bethesda 6 (14 times) compared to ACR-TIRADS 3.
• No statistically significant association was found between nodule size and Bethesda classification across ACR-TIRADS categories.

Conclusions:

• Nodule size is not a significant factor in determining the need for FNA biopsy in ACR-TIRADS 3 and 4 thyroid nodules.
• Ultrasound-based risk stratification (ACR-TIRADS) and cytopathology (Bethesda) are primary determinants for managing suspicious thyroid nodules.
• Focusing on nodule size may not be essential for FNA biopsy indication in high-suspicion thyroid nodules.