Factors affecting the false negativity of fine-needle aspiration biopsy in thyroid nodules with indeterminate cytology

Purpose: False negative results of fine needle aspiration biopsies (FNAB) remain one the most important problems in management thyroid nodules. The aim this study was to evaluate factors affecting false FNAB, especially nodules with indeterminate cytology.
 Materials and Methods: Patients who underwent FNAB subsequent thyroidectomy between January 2017 2020 were included study. performed on suspicious according TIRADS classification. Nodules "atypia/follicular lesion undetermined significance (AUS/FLUS)", "non-diagnostic (ND)" cytology or "follicular neoplasm/suspicious for follicular neoplasm (FN/SFN)" defined as "indeterminate (IC)". analyzed two groups. Group-1, while true positive Group-2. Demographic clinical data, pathologic genetic profiles patients statistically compared all IC group separately.
 Results: final pathology discordant 94 (Group-1) concordant 233 (Group-2). In subgroup, 56 95 IC/Group-1 39 IC/Group-2. accuracy significantly higher presence extrathyroidal extension (71.4% vs. 30.8%), perineural/lymphovascular invasion (60.0% 29.6%), classical variants (68.5% 50.7%), non-encapsulated tumors (67.9% 50.0%) multicentricity (47.2% 24.1%). group, thyroiditis (75.0% 49.2%) high serum Anti-TPO levels 30.7%) increased rate negativity FNAB. High Neutrophil Lymphocyte Ratio (NLR) small tumor size also increase patients.
 Conclusion: diagnostic is variant expected be aggressive due extra-thyroidal extension, invasion, multicentricity. It should kept mind that thyroiditis, level anti-TPO NLR.