Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules Measuring Less than 5 mm: Effects on Specimen Adequacy and Diagnosis

Abstract

Objective: We aimed to assess the adequacy and efficacy of ultrasound (US)-guided fine-needle aspiration (US-FNA) for small solid thyroid nodules (SSTNs) with the largest diameter <5 mm and compared these according to nodule size. Study Design: Among 656 SSTNs in 569 patients, each SSTN was classified into 1 of 4 groups according to the largest diameter: 1 mm ≤ group A < 2 mm; 2 mm ≤ group B < 3 mm; 3 mm ≤ group C < 4 mm, and 4 mm ≤ group D < 5 mm. We compared the adequacy and efficacy of US-FNA between these groups using histopathologic results as a reference standard. Results: 571 (87.0%) SSTNs were adequately sampled by US-FNA and 200 of these were histopathologically confirmed. The adequacy of US-FNA for SSTNs varied according to the nodule diameter: the smaller the nodule diameter, the lower the diagnostic adequacy. The diagnostic efficacy of US-FNA for SSTNs showed a significant relationship with nodule size: diagnostic efficacy in groups A and B was lower than in groups C and D. Conclusions: The adequacy of US-FNA for SSTNs tended to decrease with decreased nodule size, and diagnostic efficacy of US-FNA for SSTNs with the largest diameter <3 mm was lower than for those ≥3 mm.

Size and Ultrasound Features Affecting Results of Ultrasound‐Guided Fine‐Needle Aspiration of Thyroid Nodules

“…Compared to prior studies, our total sensitivity and PPV were in the upper range, and the total specificity and NPV were in the lower range because of the small percentage of benign nodules in this pathologically based study. Previous studies reported 1.4% to 10.5% false‐negative rates and 1.9% to 31% false‐positive rates for US‐guided FNA comparing cytologic and corresponding histopathologic results . The total false‐negative and false‐positive rates in this study were 4.7% and 16.7%, respectively.…”

“…Bethesda I FNA results are the main drawback of the FNA technique. Kim et al reported that for 200 resected nodules smaller than 5 mm in diameter, the cytologic results tended to be nondiagnostic in tumors with small sizes. We agree with this conclusion, as tiny nodules have lower tissue volumes for aspiration (Figure ).…”

Factors Influencing the Reliability of Thyroid Fine-Needle Aspiration: Analysis of Thyroid Nodule Size, Guidance Mode for Aspiration and Preparation Method

“…However, the size of the smallest nodule that can be assessed with FNA is unclear. Some authors believe that the accuracy of FNA is reduced in nodules <6 mm [19], whereas other authors have shown that the diagnostic efficacy of FNA is lower for nodules with a maximum diameter of <3 mm [20]. The American Thyroid Association does not recommended routine FNA for nodules <5 mm because highly inadequate cytology specimens are produced [21].…”

Diagnostic value of ultrasound features and sex of fetuses in female patients with papillary thyroid microcarcinoma

“…Nevertheless, FNA has limitations in subcentimeter nodules as a result of its high rates of inadequate cytological specimens and false positive findings, especially for nodules less than 5 mm 4 . Therefore, it is essential to find new methods to improve the accuracy of PTMC diagnosis.…”