Value of ultrasound-guided fine-needle aspiration biopsy of thyroid nodules in an endemic goitre area

The aim of this study was to determine the value, advantages and limitation s of ultrasound-guided fine-needle aspiration biopsy (US-FNAB) in an endemi c goitre area. US-FNAB was performed on all outpatients who presented with hypoechoic and/or hypofunctional and/or growing nodules. A total of 4518 US -FNABs were performed and 718 patients from this series underwent surgery, Cytological results of the primarily performed US-FNAB of these patients we re compared retrospectively with the histological results. US-FNAB results were grouped as (1) non-malignant (n=303), (2) non-malignant follicular pro liferation (n=177), (3) malignancy cannot be ruled out (n=133), (4) maligna nt (n=61), (5) inadequate (n=34), and (6) sampling error; biopsy of a non-m alignant nodule (n=10). Nodules as small as 5 mm in diameter could be biops ied, gaining representative material. US-FNAB found a malignant or suspicio us cytology in 65 out of 87 cases with malignant histology (74.71%). Diagno sis of early tumour stages was often possible: 12 of 18 thyroid carcinomas biopsied and smaller than 10 mm in diameter had malignant or suspicious cyt ology (groups 3 and 4). US-FNAB was performed incorrectly within non-malign ant nodules in ten patients (1.39%) with multinodular goitre (ten papillary carcinomas, nine smaller than 10 mm), Regarding the cytology of groups 1 a nd 2 as benign and those of groups 3 and 4 as malignant, US-FNAB performanc e was as follows: sensitivity 87.84%, specificity 78.50%, negative predicti ve values 98.13%, positive predictive values 33.51% and accuracy 79.53%. Bi opsies with inadequate material were obtained in 4.73% of all biopsies. No major adverse effects occurred. Re-biopsies in 61 cases did not alter the c ytological outcome in those cases where adequate material was obtained. US- FNAB is a valuable method in the pre-operative assessment of thyroid nodule s in order to select patients for surgery, as malignancy can often be detec ted even in early tumour stages. However, even with ultrasonographic guidan ce, the minimal tumour size detectable by US-FNAB is around 5 mm, The cytol ogical interpretation in cases with regression and microfollicular prolifer ation also sets limits on the method, However, patients with non-malignant cytologies can be followed up safely by sonography due to thp high NPV nf U S-FNAB ac long ac thyroid nodules do not become larger. Re-biopsies seem to be of limited value as long as adequate material was obtained by US-FNAB.