[Malignancy markers in the cytodiagnosis of thyroid nodules. Thyroid peroxidase]

The enzyme thyroid-peroxidase (TPO) possesses in thyroid malignancy an immunological alteration disclosed by an anti-TPO monoclonal antibody termed MoAb47: a negative immunostaining with MoAb47 thus represent a marker of malignancy for thyroid tumors. The present work has been intended to investigate the ability of TPO immunodetection to assist the diagnosis of malignancy in fine-needle aspirates (FNA) of thyroid nodules. The study concerns 300 patients with histologically proven thyroid nodules. The results of TPO immunodetection have been compared to the final histological diagnosis and in 279 cases, to the results of standard cytological analysis. From 248 benign nodules, 215 yielded more than 80% positive cells. All malignant nodules had less than 80% positive cells and most of them less than 40%. According to these results, with 80% positive cells as the threshold between benign and suspicious or malignant results, the sensitivity of the method for the screening of malignancy is 100%, its specificity 86.7% and its overall accuracy 89%.