Reevaluation of thyroid fine-needle aspiration according to bethesda system and histopathological correlation

BACKGROUND: The Bethesda system recently proposed seven diagnostic categories forthe classification of thyroid fine-needle aspiration (FNA) cytology. Using these categories,the experience with FNA from our pathology departmant was studied with emphasis oncytologic-histologic correlation, source of errors, and clinical management.METHODS: Patient cytology data were retrieved by a retrospective search of thyroid FNAin the institutional databases. Cytologic diagnosis were classified as unsatisfactory, benign,atypical follicular cell of unknown significance, suspicious for follicular neoplasm (FN),suspicious for Hürthle cell neoplasm, suspicious for malignancy, and positive for malignancy.The present study included 206 consecutive patients who underwent FNA, and subsequentlysurgery.RESULTS: Of 206 FNA samples, 24 % were classified as unsatisfactory, 58 % wereclassified as benign, 4 % were classified as AFC-US, 9 % were classified as suspicious forFN ( including Hürthle cell neoplasm), 4 % were classified as suspicious for malignancy, and3 % were classified as malignant. The rates for histologically confirmed malignancy in thesecategories were 8 %, 1 %, 38 %, 25 %, 62 % and 100 %, respectively. Sources of errorsincluded diagnoses on inadequate spesmen, sample errors, and overlapping cytologic featuresbetween hyperplastic nodules and follicular adenoma. The sensitivity and specificity ofthyroid FNA for the diagnosis of malignancy were 83.3 % and 100 %, for previous cytologicresults, respectively. The sensitivity and specificity of thyroid FNA for the diagnosis ofmalignancy were 85.7 % and 100 %, for Bethesda system cytologic results, respectively.CONCLUSIONS: The current results indicated that FNA provides an accurate diagnosisof thyroid nodules. The seven diagnostic categories were benefical for triaging patients foreither clinical follow-up or surgical management.