[Cancer in thyroid nodules: evaluation of ultrasound and fine-needle aspiration biopsy]

Thyroid nodules are a very common clinical problem and fine-needle aspiration biopsy (FNAB) is its main diagnostic test. Recently, it has been shown that some ultrasonographic features are associated to an increased risk of cancer, but a comparison between FNAB and ultrasonography (US) or its combination is not available. The aim of this study was to evaluate FNAB and US performance, isolated or combined, for cancer diagnosis in thyroid nodules.

Eighty patients, with palpable solitary thyroid nodules or multinodular goiters, who were to undergo surgery, were selected among 289 patients seen in our clinic between March, 1995 and July, 1997. US and FNAB were performed by one of us. US was considered positive for cancer when microcalcifications, absent halo or hypoechogenicity were seen. FNAB was considered positive for cancer when it was either suspicious or compatible with malignancy. Both methods (FNAB and US) were evaluated in parallel combination (positive when FNAB or US was positive) and in serial combination (positive when both, FNAB and US, were positive).

Sensitivity and specificity of FNAB and US for cancer diagnosis in thyroid nodules were, respectively, 87% and 62%, and 81% and 70%. Serial combination of FNA and US had sensitivity of 69% and specificity of 91%, and parallel combination resulted in sensitivity of 94% and specificity of 52%.

The US had good accuracy in the evaluation of thyroid nodules, and can help us take some decisions in the clinical practice, supplementary to FNA. Nevertheless, the quality of the ultrasound examination depends on the experience of the examiner and on the characteristics of the equipment, so new studies are necessary to evaluate these factors to the current usage of ultrasonographic characteristics in the evaluation diagnostic of thyroid nodules.