Background: Thyroid nodules are frequently seen in the general population. Preoperative discrimination between benign and malignant nodules is essential to avoid unnecessary surgery. Fine-needle aspiration cytology has greatly improved the clinical management of thyroid nodules. Follicular neoplasms, representing the indeterminate group by fine-needle aspiration cytology (FNAC), constitute a diagnostic problem. The aim of the study was to assess the diagnostic effect of galectin-3 and minichromosome maintenance protein2 (MCM2) expression in distinguishing benign from malignant thyroid nodules preoperatively.
Patients and methods: This was a prospective study that enrolled 79 patients who presented with thyroid enlargement and who were referred for fine-needle aspiration to the Cytology unit of Kasr Al-Aini Hospital, and the National Cancer Institute, between April 2008 and November 2009. Morphological and immunocytochemical analyses of FNA-derived cell block preparations were evaluated. Immunocytochemical assays using mouse monoclonal antibodies galectin-3 Ab-1 and MCM2 Ab-1 were performed preoperatively on follicular thyroid proliferations that were candidates for surgery, and their diagnostic accuracy was compared with the final histological findings.
Results: Sixty patients were included in the study and 19 were excluded (unsatisfactory results or lack of histological diagnosis). In this prospective study, FNAC, diffuse overexpression of galectin-3 and mean of MCM2 labeling index could discriminate benign from malignant thyroid lesions with sensitivities of 60, 90, and 66.7%, specificities of 100, 100, and 83.3%, and diagnostic accuracies of 80, 95, and 75%, respectively.
Conclusion: Galectin-3 expression is a very useful complementary marker for FNAC, increasing its sensitivity to detect malignant cases, especially if assessed semiquantitatively. The mean of MCM2 labeling index was higher in malignant thyroid lesions and it is a promising marker for future study, as high MCM2 scoring significantly suggests the lesion’s behavior.