Value of additional von Kossa staining in thyroid nodules with echogenic spots on ultrasound.

Purpose: To evaluate the clinical value of additional von Kossa staining on cytology in thyroid nodules with echogenic spots on ultrasound (US).

Materials And Methods: 342 thyroid nodules were analyzed for cytology and von Kossa staining was performed to detect microcalcifications. We compared diagnostic performances and accuracies of FNA and FNA with von Kossa staining to detect malignancy. We evaluated associations of aggressive pathologic features and von Kossa positivity in the surgically confirmed papillary thyroid carcinoma (PTC) group.

Results: Two hundred and thirty two (67.8%) nodules were malignant and 110 (32.2%) were benign on cytopathology. Compared to cytology alone, additional von Kossa staining slightly improved sensitivity from 89.7% to 90.9% (P=0.081). In 207 cases of surgically confirmed PTC, von Kossa positivity was an independent predictor of central lymph node metastasis in PTCs by multivariate analysis (odds ratio, 2.218; P=0.021).

Conclusions: Adding von Kossa staining to cytology improved the sensitivity of thyroid nodules with echogenic spots on US. Positive von Kossa stains in PTCs may also be useful in predicting central lymph node metastasis.