Can cut-off points of 10 and 15 mm of thyroid nodule predict malignancy on the basis of three diagnostic tools: i) strain elastography, ii) the Bethesda System for Reporting Thyroid Cytopathology with 27-gauge fine-needle, and iii) histopathology?

Purpose: This study evaluated whether the cut-offs 10 and 15 mm can help distinguish malignant from benign nodules regarding three diagnostic tools: i) strain elastography (SE), ii) the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), iii) histopathology. Methods: From 2012 to April 2015, a retrospective analysis was conducted by enrolling the data of 425 consecutive eligible patients with 500 thyroid nodules. The efficacy of the nodule size, as of the cut-offs, on the estimation for malignancy had been analysed on the basis of the three diagnostic tools. Results: Of the 500 thyroid nodules examined, 80 (16.0%) were under 10 mm and 420 (84.0%) were over 10 mm in diameter. No significant difference was found between over 10 mm with i) TES (Tsukuba Elasticity Score) 4 and 5, area under the curve (AUC) 0.531, ii) TBSRTC (The Bethesda System for Reporting Thyroid Cytopathology) III, IV, V, VI, undetermined and malignant cytology, AUC 0.517, iii) malignant histopathology, AUC 0.509. Similarly, no significance difference was recognized between over 15 mm with i) TES 4 and 5, AUC 0.623, ii) undetermined and malignant cytology, AUC 0.455, iii) malignant histopathology, AUC 0.515 by McNemar test. However, size over 15 mm may strengthen the prediction among TES 4 and 5 and malignant histopathology, as weakens in undetermined and malignant cytology. Conclusions: These preliminary data of 3-year single-center study suggest that assignment of 10 and 15 mm as the cut-off points of the thyroid nodules may not be predictive of malignancy on the basis of three diagnostic tools. Nevertheless, higher cut-off may corrobarate the correlation with TES 4 and 5 and malignant histopathology while attenuation with TBSRTC III, IV, V, and VI, confront with the lower one, 10 mm.