Immunocytochemical expression of Ki67 and laminin in Hurthle cell adenomas and carcinomas

Background: Hurthle cell neoplasms may occur as a benign adenoma or carcinoma; the latter displays comparatively aggressive clinical behaviour. Fine-needle aspiration cytology (FNAC) represents a reliable tool for screening Hurthle cell lesions before surgery. Nevertheless, the cytological interpretation of these lesions is not always unequivocal. We analyzed cell growth and cellular adhesiveness by means of two different antibodies, Mib1 (Ki67) and laminin. Aim: The aim of the study was to analyze Ki67 and laminin immunocytochemical expression on FNAC to evaluate their usefulness in the preoperative differential diagnosis of Hurthle cell neoplasms. Results: A higher expression of Ki67 has been recorded in malignant lesions as compared to benign ones (8% to 20% vs 1% to 5% nuclear staining respectively; p <0.001). An increased reactivity of anti-laminin antibody was recorded in the cytoplasm of cells from all malignant lesions. In Hurthle cell adenomas this adhesion molecule showed an intensity ranging from low to moderate. Moreover, a few benign lesions showing a moderate proliferative activity were associated with evident laminin expression. Conclusion: These findings support the hypothesis that benign Hurthle cell lesions with a high cellular proliferation associated with an increased laminin expression could define a subset of lesions prone to malignant transformation. Conversely, since all cases with low expression of both laminin and Ki67 always correspond to adenomas, we suggest that the different expression of these two antibodies on FNAC can provide a further tool for the preoperative identification of lesions at low risk of malignancy, thus avoiding unnecessary surgery.