The sonographic pattern of nodule and thyroid fine needle aspiration cytology in the evaluation of thyroid malignancy risk

Introduction: Thyroid fine-needle aspiration biopsy (TFNAB), which is basically planned according to the ultrasonographic features is of clinical importance; since it helps early diagnosis of malignancy, facilitates the selection of patients who will undergo thyroid surgery and prevents unnecessary surgical procedures. In our study, we aimed to evaluate the adequacy of TFNAB as well as the retrospective investigation of the link between the estimated malignancy risk and the descriptive features, radiologic findings and biopsy cytology of patients who underwent ultrasonography guided TFNAB.Methods: In this study, the ultrasonographic characteristics of 659 thyroid nodules belonging to 523 patients who underwent TFNAB between 2018 and 2021 were evaluated. The correlation between the risk of malignancy and demographic data, thyroid hormone levels, and ultrasonographic characteristics of nodules was examined. The diagnostic accuracy performances of European thyroid imaging reporting and data system (EU-TIRADS) classification prepared by the European Thyroid Association (ETA), the risk classification systems recommended by the American Thyroid Association (ATA) and the Society of Endocrinology and Metabolism of Turkey (TEMD) were compared with The Bethesda System for Reporting Thyroid Cytopathology (Bethesda). The adequacy of biopsy was also evaluated. The data which is obtained from the study was statistically analyzed by means of SPSS 20.0 (Statistical Package for the Social Sciences; SPSS Inc. Chicago, IL, USA) program.Results: In this study, the biopsies of 41 (6.2%) among 659 thyroid nodules appeared to be malignant. A statistically significant correlation was detected between malignancy and hypoechogenicity (p=0.011), microcalcification (p=0.005), irregular margins (p=0.028), and accompanying pathological lymph node (p=0.002). Compared to the surgical pathology results, the accuracy that was closest to that of Bethesda System (AUC: 0.778) (Area Under Curve) was found in EU-TIRADS (AUC:0.715). In the biopsies performed in our own endocrinology clinic (43.7% of the total biopsies), the ratio of non-diagnostic results was found to be 8.3%, whereas it was 29.1% in the biopsies performed in other clinics (56.3% of the total biopsies).Conclusion: It should always be kept in mind that, in the cytologic evaluation, the ultrasonographic nodule pattern recommended by the guidelines is very important in the management of patients, because cytology may show false negative and false positive results as well as unclear or non-diagnostic pathological findings. However, clinicians should also understand that classification systems may have strengths and weaknesses. Our study also emphasizes the importance of how experienced a clinic performing biopsy is as well as the role of cytopathologist in obtaining diagnostic results in biopsy.Keywords: Thyroid nodule, neoplasia, ultrasonography, biopsy fine-needle