Fine needle aspiration and core needle biopsy techniques in the diagnosis of nodular thyroid pathologies

It is widly accepted that Fine Needle Aspiration Biopsy (FNAB) is the main test to distinguish benign from malignant thyroid lesions. Nevertheless, this technique presents some limits such as the possibility of false-negative or inadequate samples and it is unable to cytologically discriminate among adenomathosus goiter, follicular adenoma and well-differentiated follicular carcinoma. The aim of this study was to evaluate the possibility of restricting these limitations using Core Needle biopsy (CN) technique. Therefore we selected for CN, 40 out of 136 patients who underwent FNAB during a one year period; among these patients only 32 agreed a to this technique. Forty-two out of 136 patients underwent surgery; 29 of them were subjected to both biopsies. Sixteen of the diagnostic microbiopsies have been histologically confirmed. We had no discordant cases between cytological and microhistological diagnosis, except for one case which appeared cytologically colloid goiter, microhistologically follicular neoplasm and histologically follicular adenoma. In this case it was not possible to microhistologically discriminate benign from malign follicular lesion. In our experience not all patients accepted CN biopsy as well as FNAB and, moreover, this technique showed no advantage over FNAB diagnosis. On this base we think that actually FNAB should be the main procedure in the diagnosis of the thyroid lesions. It is easily performed, accepted by the patients and has a low cost-benefit ratio. If the sample is not diagnostic it can be easily repeated and false-negative cases could be discovered thanks to an adequate clinical and ultrasonographical follow-up of the patients.