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International Journal of Endocrinology
Volume 2016, Article ID 3803647, 6 pages
http://dx.doi.org/10.1155/2016/3803647
Research Article

Does Tumor Size Influence the Diagnostic Accuracy of Ultrasound-Guided Fine-Needle Aspiration Cytology for Thyroid Nodules?

1Department of Surgery, Seoul National University Boramae Medical Center, 20 Boramae-ro 5-gil, Dongjak-gu, Seoul 156-70, Republic of Korea
2Department of Surgery, Haeundae Paik Hospital, Inje University College of Medicine, 875 Haeundae-ro, Haeundae-gu, Busan 612-030, Republic of Korea
3Department of Surgery, Seoul National University Hospital, College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea
4Cancer Research Institute, Seoul National University, College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea
5Division of Surgery, Thyroid Center, Seoul National University Cancer Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea
6Department of Radiology, Seoul National University Hospital, College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea
7Department of Pathology, Seoul National University Hospital, College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Republic of Korea

Received 26 May 2016; Revised 12 August 2016; Accepted 30 August 2016

Academic Editor: Diego Russo

Copyright © 2016 Do Hoon Koo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Fine-needle aspiration cytology (FNAC) is diagnostic standard for thyroid nodules. However, the influence of size on FNAC accuracy remains unclear especially in too small or too large thyroid nodules. The objective of this retrospective cohort study was to investigate the effect of nodule size on FNAC accuracy. Methods. All consecutive patients who underwent thyroidectomy for nodules in 2010 were enrolled. FNAC results (according to the Bethesda system) were compared to pathological diagnosis. The nodules were categorized into groups A–E on the basis of maximal diameter on ultrasound (≤0.5, >0.5–1, >1-2, >2–4, and >4 cm, resp.). Results. There were 502 cases with 690 nodules. Overall FNAC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95.4%, 98.2%, 99.4%, 86.4%, and 96.0%, respectively. False-negative rates (FNRs) of groups A–E were 3.2%, 5.1%, 1.3%, 13.3%, and 50%, respectively. Accuracy rates of groups A–E were 96.8%, 94.8%, 99%, 94.7%, and 87.5%, respectively. Conclusion. Although accuracy rates of FNAC in thyroid nodules smaller than 0.5 cm are comparable to the other group, thyroid nodules larger than 4 cm with benign cytology carry a higher risk of malignancy, which suggest that those should be considered for intensive follow-up or repeated biopsy.