US-Guided Fine-Needle Aspiration of Papillary Thyroid Microcarcinoma in Non-Screening Settings: Diagnostic Errors and Mitigation Strategies
- 1Security Force Hospital, Riyadh, Saudi Arabia.
Abstract
BackgroundPapillary thyroid microcarcinoma (PTMC, [≤]1 cm) is increasingly diagnosed, and a subset behaves aggressively. Preoperative ultrasound (US) and fine-needle aspiration (FNA) accuracy in this size range, particularly with multinodular disease, is poorly defined outside East Asian screening cohorts.
Materials and MethodsWe retrospectively analyzed 180 consecutive PTMC cases (2017- 2026) with preoperative US and FNA and compared them with 191 benign thyroidectomy controls. ROC analysis identified an optimal size cutoff. We compared sensitivity, specificity, PPV, NPV, and accuracy across tumor-size subgroups, before/after 2023, and with/without dominant nodules (DNs) [≥]2 cm.
ResultsROC analysis identified 5 mm as the optimal cutoff (AUC 0.80). FNA sensitivity was 44.4% overall, falling to 14.1% for tumors <5 mm versus 61.2% for [≥]5 mm, with specificity uniformly high (94.8%). US showed a similar pattern (sensitivity 23.4% vs. 64.7%) but lower specificity (69.6%), driven largely by calcification and Hashimotos-related hypoechogenicity. Combined FNA+US improved sensitivity to 59.4%. DNs [≥]2 cm markedly reduced FNA true-positive rates (67.9% vs. 10.8%; OR 17.4). Excluding DN cases raised FNA sensitivity to 67%, NPV to 84.2%, and accuracy to 85.2%. Post-2023 experience significantly improved all metrics (sensitivity 34.4% to 54.4%).
ConclusionFNA and US sensitivity for PTMC decline sharply below 5 mm and in multinodular glands with dominant nodules, while specificity/PPV remain high. A 5 mm threshold, operator experience, and selective avoidance of FNA in dominant-nodule-bearing multinodular goiters (favoring direct surgical referral) can meaningfully improve diagnostic performance and guide management.
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BibTeX
@misc{el2026usguided,
title = {{US-Guided Fine-Needle Aspiration of Papillary Thyroid Microcarcinoma in Non-Screening Settings: Diagnostic Errors and Mitigation Strategies}},
author = {I. EL HAG and M. T. Al Shammary and R. Tallab and S. Patil and A. Alghamdi},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.06.26364827},
url = {https://www.medrxiv.org/content/10.64898/2026.10.06.26364827v1},
note = {CC0},
}
RIS
TY - UNPB
TI - US-Guided Fine-Needle Aspiration of Papillary Thyroid Microcarcinoma in Non-Screening Settings: Diagnostic Errors and Mitigation Strategies
AU - I. EL HAG
AU - M. T. Al Shammary
AU - R. Tallab
AU - S. Patil
AU - A. Alghamdi
PY - 2026
DA - 2026/10/06
PB - medRxiv
DO - 10.64898/2026.10.06.26364827
UR - https://www.medrxiv.org/content/10.64898/2026.10.06.26364827v1
AB - BackgroundPapillary thyroid microcarcinoma (PTMC, [≤]1 cm) is increasingly diagnosed, and a subset behaves aggressively. Preoperative ultrasound (US) and fine-needle aspiration (FNA) accuracy in this size range, particularly with multinodular disease, is poorly defined outside East Asian screening cohorts. Materials and MethodsWe retrospectively analyzed 180 consecutive PTMC cases (2017- 2026) with preoperative US and FNA and compared them with 191 benign thyroidectomy controls. ROC analysis identified an optimal size cutoff. We compared sensitivity, specificity, PPV, NPV, and accuracy across tumor-size subgroups, before/after 2023, and with/without dominant nodules (DNs) [≥]2 cm. ResultsROC analysis identified 5 mm as the optimal cutoff (AUC 0.80). FNA sensitivity was 44.4% overall, falling to 14.1% for tumors <5 mm versus 61.2% for [≥]5 mm, with specificity uniformly high (94.8%). US showed a similar pattern (sensitivity 23.4% vs. 64.7%) but lower specificity (69.6%), driven largely by calcification and Hashimotos-related hypoechogenicity. Combined FNA+US improved sensitivity to 59.4%. DNs [≥]2 cm markedly reduced FNA true-positive rates (67.9% vs. 10.8%; OR 17.4). Excluding DN cases raised FNA sensitivity to 67%, NPV to 84.2%, and accuracy to 85.2%. Post-2023 experience significantly improved all metrics (sensitivity 34.4% to 54.4%). ConclusionFNA and US sensitivity for PTMC decline sharply below 5 mm and in multinodular glands with dominant nodules, while specificity/PPV remain high. A 5 mm threshold, operator experience, and selective avoidance of FNA in dominant-nodule-bearing multinodular goiters (favoring direct surgical referral) can meaningfully improve diagnostic performance and guide management.
ER -