Evaluation of Thyroid Nodules in Patients With Fine-Needle Aspiration Biopsy

The incidence of thyroid nodules has increased in the last 50 years due to the widespread use of imaging methods and incidental detection of small thyroid nodules. Thyroid fine-needle aspiration biopsy (FNAB) is the most accurate, reliable, and cost-effective test to evaluate thyroid nodules.

In this research, we aimed to elucidate thyroid fine-needle aspiration cytology (FNAC) to understand how suspicious cases predict malignancy.

Within this research's scope, 411 patients over 16 years old who were evaluated in Izmir Katip Celebi University, Ataturk Training and Research Hospital Internal Medicine (Izmir, Turkey) outpatient clinic for thyroid nodules between 2018 and 2022 and underwent thyroid FNAC followed by thyroid surgery were analyzed retrospectively. The age, gender, thyroid FNAC, operation type, and histopathology of all the patients were reviewed. Individuals with a history of head and neck cancer were excluded from the analysis.

No statistically significant relationship between the pathology results and demographic characteristics was found. A statistically significant correlation existed between the pathology and FNAB results (p<0.05). Although 84.5% of the patients were diagnosed as benign, 14.7% as suspicious, and 0.8% as malignant in FNAC, all of these cases were diagnosed as benign in final histopathology results. Similarly, 21.9% of the patients were diagnosed as benign, 58.8% as suspicious, and 19.4% as malignant in FNAC and all of these cases were diagnosed as malignant in final histopathology results. A correlation was determined between the two measurements (Cohen's kappa (κ)=0.557; p<0.001). The test's sensitivity was 47%, and the specificity was 99.1%. According to the FNAC results, the rate of being diagnosed with malignancy (positive predictive value (PPV)) was 93.9%, and the rate of being diagnosed as benign (negative predictive value (NPV)) was 85.8% for the individuals initially diagnosed as benign.

Although FNAB remains the most important diagnostic tool to identify benign cases with a high accuracy rate, the operation decision is not clear in suspicious atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS) cytology findings. In conclusion, this study highlights the importance of FNA results and helps in surgical decision-making by emphasizing that the possibility of malignancy in the post-operative final histopathology report is higher, especially in the presence of suspicious FNAC results.