The Association of Non-diagnostic Result and Thyroid Cancer in Patients Who Underwent Fine Needle Aspiration Biopsy

Based on the Bethesda Thyroid Cytopathology Reporting System 2017, the risk of non-diagnostic (ND) cytology malignancy was reported to be 5–10%. The present study aimed to determine the non-diagnostic rates in patients who underwent thyroid fine needle aspiration biopsy due to thyroid nodules, to investigate the factors affecting thyroid cancer diagnosis in patients whose fine needle aspiration biopsy result was non-diagnostic, to determine the malignancy rates in patients with the non-diagnostic cytological result, and to compare them with the literature. Patients who underwent thyroid fine needle aspiration biopsy under the guidance of thyroid ultrasonography (USG) between January 2011 and January 2020 and whose results were non-diagnostic were included in this study. Patients whose fine needle aspiration biopsy results turned out to be non-diagnostic were retrospectively screened in the automation system of our hospital. In our research, the malignancy rate of thyroid nodules whose fine needle aspiration biopsy result was non-diagnostic at baseline was 2.7% (23/846). Of the 846 patients with non-diagnostic cytological diagnosis included in our study, 114 (13.4%) underwent surgery. Of the 114 patients who underwent surgery, 23 (20.1%) had malignant pathology results. In our study, T4 level (p = 0.003), age (p < 0.001), and microcalcification (p < 0.001) were statistically associated with malignancy. The findings showed that the presence of microcalcification, low age, and low T4 level increases the risk of malignancy in patients whose fine needle aspiration biopsy cytology result was non-diagnostic. Clinicians may consider these findings as complementary markers for patient management protocols whose repeated fine needle aspiration biopsy results were non-diagnostic.