Factors Affecting Malignancy in Thyroid Nodules with Non-Diagnostic Fine Needle Aspiration Biopsy Result

Introduction:Non-diagnostic (ND) fine needle aspiration biopsy (FNAB) results are problematic for clinicians who want to accurately diagnose malignancy and avoid unnecessary thyroidectomies. In this study, we aimed to investigate the incidence of malignancy in nodules whose first FNAB result was ND, and ultrasonography (USG) findings affecting malignancy and the effectiveness of repetitive biopsies.Patients and Method:In our clinic, 156 consecutive nodules whose first FNAB were ND according to the Bethesda system and underwent thyroidectomy between 1 January 2011 and 1 January 2018, directly or after repeated biopsies, were retrospectively analyzed.Results:Malignancy was detected in 44 (28%) of 156 nodules that were ND in the first FNAB. Twenty-two (31%) of 72 nodules that underwent FNAB for the second time resulted in ND again. The malignancy rate of nodules with two consecutive ND results was 23%. Of the USG features, a significant correlation was found between malignancy and solid nodule structure (p<0.001), microcalcification (p=0.025), cervical lymphadenopathy (LAP) (p=0.004) and medium-high risk USG pattern (p=0.002). In multivariate analysis, only the solid nodule structure (p<0.002) and the presence of cervical LAP (p=0.013) resulted as independent predictive factors.Conclusion:Diagnostic thyroidectomy is an effective method for reaching the diagnosis in selected patients considering the USG findings.