Malignancy Risk Stratification in Thyroid Nodules with Benign Results on Cytology: Combination of Thyroid Imaging Reporting and Data System and Bethesda System
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The indications of repeat fine-needle aspiration (FNA) for thyroid nodules with benign results of the Bethesda system were investigated.
A total of 1,398 nodules were classified according to the Thyroid Imaging Reporting and Data System (TIRADS). TIRADS category 3 included nodules without solidity, hypoechogenicity or marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, and taller-than-wide shape on ultrasonography (US). Categories 4a, 4b, 4c, and 5 included nodules with one, two, three or four, or five suspicious US features, respectively. The malignancy risks, and odds ratio (OR) with 95 % confidence interval (CI) were calculated. Analyses were performed for all nodules, nodules >10 mm, and nodules ≤10 mm.
Of 1.398 nodules, 43 (3.1 %) were malignanct. The malignancy risks of benign nodules with categories 3, 4a, and 4b were 0.7, 1.2, and 0.7 %, respectively, whereas those for nodules with categories 4c and 5 were 9.8 and 22.2 %, respectively. The ORs of nodules with categories 4c and 5 were 19.4 (95 % CI 5.0–76.2) and 50.6 (95 % CI 10.4–245.0), respectively. In nodules >10 mm, the malignancy risks of categories 4c and 5 were 2.7 and 20 %, respectively, and the ORs were 10.7 (95 % CI 1.2–93.7) and 236.1 (95 % CI 12.6–4426.4), respectively. In nodules ≤ 10 mm, the malignancy risks of categories 4c and 5 were 12.6 and 22.6 %, respectively, and the ORs were 10.1 (95 % CI 1.3–78.0) and 18.9 (95 % CI 2.1–168.9), respectively.
Repeat US-guided FNA should be considered in benign thyroid nodules with three or more suspicious US features regardless of size.
KeywordsThyroid Nodule Nodule Size Benign Nodule Irregular Margin Malignancy Risk
This study was supported by a faculty research grant of Yonsei University College of Medicine for 2013 (6-2013-0074).
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