The Evaluation of Malignancy Rates of Nondiagnostic Cases in Thyroid Fine-Needle Aspirations

Aim: In this study, it was aimed to investigate the malignancy rates of nondiagnostic (ND) thyroid fine-needle aspiration cytology (FNAC) material by evaluating either the result of the second FNAC or resection/biopsy materials.Method: Among the 1165 thyroid FNAC cases evaluated in the Pathology Department of Başakşehir Çam and Sakura City Hospital within 9 months (October 2020-June 2021), 102 cases (8,7%) diagnosed with ND were included in the study. At the end of the 6-15 months follow-up period after the diagnosis of ND, the results of the second FNAC or resection (thyroidectomy, lobectomy)/biopsy of the cases were evaluated. Diameter and sonographic features of thyroid nodules (solid, cystic, mixed) were also noted.Results: 49% of the cases (n:50) had a second FNAC. Resection/biopsy was performed in only 12 (11,8%) cases. Of these 62 cases, 39 were diagnosed by second FNAC and 7 by resection/biopsy as benign (74,1%), and 5 cases were diagnosed as malignant by resection/biopsy. 7 cases were diagnosed as nondiagnostic again after the second FNAC. Final diagnosis (by resection) of the case whose second FNAC result was reported as suspicious for malignancy was papillary microcarcinoma. This case was included in the group ‘diagnosed as malignant only by resection/biopsy. In other words, malignancy was detected in 5 of 62 patients who underwent a second FNAC or resection/biopsy. The risk of malignancy was found to be 8% in the patient population included in the study with the diagnosis of ND.Conclusion: A low rate of NE results were found in this ultrasound-guided thyroid series (8,7%). After the second FNAC or resection, malignancy rates was found to be 8%. Although this result is compatible with the results of some studies, it is considerably lower than others. It would be appropriate to follow up on ND nodules with their clinical/sonographic features. Additional studies with large series will be more helpful in determining the malignancy rates of the ND group.