Value of Additional von Kossa Staining in Thyroid Nodules with “Suspicious for Malignancy” on Cytology

Abstract

Background and Objectives: We investigated the clinical value of additional von Kossa staining in thyroid nodules with “suspicious for malignancy” on cytology. Materials and Methods: From March 2010 to November 2010, 55 patients with 55 nodules which were diagnosed as “suspicious for malignancy” on cytology and had microcalcifications on ultrasound (US) underwent surgery and made up our final study population. We evaluated the role of the von Kossa stain as a preoperative diagnostic factor for thyroid cancer using histopathology as the “gold standard”. Diagnostic performances were calculated of the presence of psammoma bodies on both cytology and the von Kossa staining and of US in predicting thyroid cancers. Results: Of 55 nodules with microcalcifications on US and “suspicious for malignancy” on cytology, 53 (96.4%) were malignant and 2 (3.6%) were benign on histopathology. All pathologically benign nodules were negative on the von Kossa stain. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the von Kossa stain were 28.3%, 100%, 30.9%, 100%, and 5% for diagnosis, respectively. Conclusion: Von Kossa staining can be a valuable diagnostic tool in a thyroid nodule with “suspicious for malignancy” on cytology and microcalcifications on US, objectively.