Evaluation of thyroid nodules by fine needle aspiration cytology - abstract

ABSTRACT

A prospective pilot study was undertaken to correlate the results of fine needle aspiration cytology (FNAC) and routine histology, in cases of nodular goitre, in order to assess the reliability of FNAC, as a diagnostic tool. Forty-eight patients with nodular (clinically single or multi-nodular) goitres had FNAC performed by standard technique under general anaesthesia just before the operation. Cytological evaluation of the aspirate compared with the histology as reported independently by the duty staff pathologist. Of the 48 cases, 13 smears were reported as "inadequate for diagnosis" (most of these near the start of the study) and 3 smears as "inconclusive". The FNAC positive and negative predictive values were respectively 0.75 and 0.72. The FNAC false positive rate of 6 out of 25 (24 percent) is high, but this still means that 19 out of 25 patients with hyperplasia might have been spared surgery. Of more importance is the FNAC false negative rate of 2 out of 7 as this would be the rate of missing a neoplasm and inducing surgical delay. Our results do not compare well with most large series; although FNAC could become, in our hands, a technique reliable enough to guide clinicians in selecting those nodular goitres which should be explored and thereby decrease the rate of unnecessary thyroid surgery, it is a technique requiring experience before reliable results are obtained (AU)