Malignancy rate in sonographically suspicious thyroid nodules of less than a centimeter in size does not decrease...

Area of Science:

• Endocrinology
• Oncology
• Cytopathology

Background:

• Thyroid nodules are common, and fine needle aspiration cytology (FNAC) is crucial for diagnosis.
• Subcentimeter nodules present unique challenges in diagnostic accuracy and management decisions.

Purpose of the Study:

• To evaluate the malignancy and nondiagnostic rates of FNAC in subcentimeter thyroid nodules based on subdivided size.
• To determine if nodule size alone should influence the decision to perform FNAC.

Main Methods:

• Retrospective review of 2,756 subcentimeter thyroid nodules and 7,105 nodules ≥1 cm with suspicious sonographic features.
• Analysis of FNAC results, including malignancy, nondiagnostic rates, and suspicious for malignancy, stratified by nodule size intervals.

Main Results:

• Subcentimeter nodules with suspicious sonographic features had a higher malignancy rate (19.7%) than larger nodules (7.8%).
• Nondiagnostic FNAC rates increased significantly in smaller nodules (<5 mm vs 6-9 mm; 24.3% vs 18.1%).
• Malignancy rates were similar between smaller and larger groups, but 'suspicious for malignancy' was higher in smaller nodules.

Conclusions:

• Sonographic findings and clinical risk factors, not just nodule size, should guide the decision for FNAC in subcentimeter thyroid nodules.
• Smaller nodule size correlates with increased nondiagnostic cytology results, impacting diagnostic yield.