Diagnosis of follicular carcinoma of the thyroid: role of sonography in preoperative diagnosis of follicular nodules.

The purpose of this study was to evaluate sonographic examination, as well as other clinical tests, for clarifying the parameters for predicting follicular carcinoma in follicular nodules of the thyroid. Nine hundred and ten consecutive patients with follicular nodules were pathologically classified as having follicular carcinoma (109 patients) or benign tumor (811 patients). Benign tumors included follicular adenoma (237 patients) and adenomatous thyroid nodules (574 patients). A case-control study was performed for follicular carcinomas and benign tumors. "Thyroglobulin 1000 ng/ml≦", "cytology class 3≦", and a "solid pattern", "low-echoic level of internal echo", and "jagged borders" of follicular carcinomas were found to be significantly higher than those of benign tumors. The sensitivities of a solid pattern (79.8%) and a low-echoic level (75.2%) were found to be relatively higher than those of other features and findings. The specificities of thyroglobulin 1000 ng/ml≦(84.0%), cytology class 3≦, and jagged borders (86.2%) were found to be relatively higher than those of other features and findings. We concluded that thyroglobulin 1000 ng/ml≦ and cytology class 3≦ in clinical features, and a solid pattern, low-echoic level, and jagged borders on sonography, indicated an increased risk of follicular carcinoma of the thyroid in follicular nodules.