Molecular markers in thyroid fine-needle aspiration biopsy: a prospective study.

BACKGROUND

Fine-needle aspiration biopsy (FNAB) is the most accurate study in the preoperative evaluation of patients with thyroid nodules. However, one of its limitations is the indeterminate or suspicious sample which accounts for 15% to 25% of the cases; both follicular and Hürthle cell neoplasms are included in this category.

OBJECTIVE

To assess the accuracy of the molecular markers HBME-1 and galectin-3 in suspicious or indeterminate FNABs comparing the results with the histologic diagnosis of the thyroidectomy specimen.

MATERIALS AND METHODS

A prospective study was carried out at 2 Health Centers in Santiago, Chile. From July 2003 to March 2008, 418 FNABs with indeterminate or suspicious diagnosis were immunostained with HBME-1 and galectin-3. Immunohistochemistry was performed on a clot obtained by FNAB, which was formalin-fixed and paraffin-embedded. The results were matched with the definitive histologic diagnosis of the thyroidectomy specimen.

RESULTS

Of 418 patients submitted to FNAB with immunohistochemistry, 138 patients underwent surgery. The sensitivity, specificity, positive predictive value, and negative predictive value were 78.67%, 84.13%, 85.51%, and 76.81%, respectively, for HBME-1 and 82.67%, 80.95%, 83.78%, and 79.69%, respectively, for galectin-3. Whereas the results for both markers combined were 94.74%, 75.81%, 82.76%, and 92.16%.

CONCLUSIONS

With the combined use of HBME-1 and galectin-3 in indeterminate FNABs, a 10% increase in sensitivity is achieved. These markers show excellent sensitivity and specificity and may improve patient's selection for surgery.