Evaluation of Risk Factors for Malignancy Obtained by Means of Fine Needle Aspiration Biopsies in Thyroid Nodules and Surgical Outcomes of Patients with Bethesda Category III (AUS/FLUS)

Background: The nodules diagnosed as the atypia of undetermined significance" category are a heterogenous group with an indeterminate risk of malignancy. This study aimed to perform a detailed cytological examination of the preparations to determine the cytomorphological criteria that may be useful to distinguish benign cases from malignant ones, correlate them with ultra-sonographic findings, and compare them with the final pathological result in surgically treated patients. Methods: The preparations of patients classified as Bethesda 3 were re-evaluated; presence or absence of one of 11 parameters (hypochromasia, oval nucleus, colloid, intra-nuclear pseudo-inclusions, nuclear grooving, nuclear moldering isolated nuclear enlargement, nuclear irregularity nuclear size, microfollicular pattern, distinct nucleoli) and correlating with surgical outcomes by adding ultrasonographic findings to statistically significant parameters. Results: Two hundred and six fine needle aspirations (FNA) procedures were classified as Bethesda 3. A total of 53 patients underwent surgery; 28 (52.8%) of them were benign, and 25 (47.1%) were malignant. Thirty-two (15.5%) accepted direct surgery 53 patients underwent repeat FNA at 3-6 month intervals and those with malignancy and repeated Bethesda 3 interpretation were operated. One hundred twenty-one (69.5%) patients who did not undergo biopsy were invited for ultra-sonographic controls at 3-6 month intervals. Among the 11 cytomorphologic parameters evaluated, 7 were found to be statistically significant (p<0.05) with malignancy When at least 3 of these parameters were positive, the malignancy rate was 92%. Malignancy was present in 19 (61.3%) of the patients with high risk nodules (TIRADS ? 4), compared to only 6 (35.8%) of the low-risk (TIRADS ? 3); there was a significant correlation between the presence of malignancy and TIRADS score (p=0.015). The preparations that displayed nucleus atypia were closely associated with the ultrasonographically high-risk group.Conclusion:The parameters indicating nuclear atypia, presence of more than 3 cytomorphological factors, TIRADS score ? 4 were significantly associated with malignancy; nuclear atypia were closely associated with the ultrasonographically high TIRADS. No significant correlation was found between the presence of "microfollicular pattern" and malignancy.