Thyroid Nodules: Too Many Fine Needle Biopsies?

Background: Fine needle biopsies are used to diagnose thyroid cancer. Nevertheless most thyroid nodules are benign so FNA is performed too often. It is very important to recognize which echographic features can help to predict benignity and avoid unnecessary biopsies. Purpose: To prospectively evaluate several ultrasonographic patterns, and the presence of comet tail artifacts, for predicting thyroid nodule benignity. Material and Methods: US findings in 1326 nodules (1079 patients) that underwent fine needle biopsies in our institution from April 2013 to February 2015 were prospectively reviewed. FNA was performed jointly by the cytology and radiology department. Nodules were assessed searching for the following US pattern appearances: spongiform, macrocystic “Honeycomb” (HC), Entirely Cystic (EC), cyst with spongiform avascular colloid clot (CCC), echogenic nodule and giraffe pattern in a thyroiditis background and presence of comets tail artifacts. Positive Predictive Value (PPV) and specificity to predict benignity were achieved. Results: 1252 nodules were included in our study, 1167 were benign and 85 malignant (confirmed by surgery). Ultrasound patterns of the 1167 benign nodules were distributed as: 17.9% spongiform, 3.8% CCC, 1.8 % HC and 1.9 % EC. In thyroiditis background, 4.1% showed echogenic nodule and 0.8% giraffe pattern. Also, 168 benign nodules showed comet tail artifacts. All nodules that presented any of the ultrasound patterns described before were benign. None of the malignant nodules showed any of the patterns evaluated. The occurrence of any pattern described when strictly evaluated, had 100% PPV and specificity to predict benignity. Conclusion: A significant number of thyroid nodule biopsies can be avoided when adequate ultrasound approach patterns are used.