Galectin-3 immunodetection for improving the performance of conventional thyroid cytology: preliminay results

Introduction: Most of differentiated thyroid carcinomas should be easily revealed by fine-needle aspiration cytology but sometimes preoperative diagnosis is doubtful. Galactin-3 is a carbohydrate –binding protein with affinity for beta-galactosides that plays a significant role in cell-cell and cell matrix adhesion, growth, neoplastic transformation and metastasis. Moreover, galectin-3 immunodetection is related to follicular thyroid malignancies. Our aim is to test Galectin-3 as potential preoperative marker for follicular and papillary carcinomas. Methods: Expression of galectin -3 was tested by fluorescence staining on 40 fresh cytological thyroid samples obtained preoperatively; the samples were fixed, stained using gal-3-specific monoclonal antibodies and treated with Rhodamine Red-conjugated anti-mouse. Counterstaining was performed using Hoechst 33342. After thyroidectomy, we analyzed correlation between gal-3-expression in FNAB and histology. Results : In our series, definitive diagnoses were: 17 multinodular goiter (A), 13 benign follicular lesions (B), 9 papillary carcinomas (C), 1 follicular carcinoma (D). Group A had shown at the FNAB a gal-3-positivity of cells from 0% to 15% (median: 10%); group B from 2% to 95 (median: 15%); group C from 30% to 90% (median: 46%). D had a 100% positivity. Conclusions: Galectin-3 immunodetection could be an useful method to improve conventional cytology’s performance in pre-operative identification of thyroid differentiated carcinomas: one “suspected” FNAB case showing 3% of positive cells proved to be benign at histology ; one “indefinite” FNAB case with 40% of positive cells proved to be malign. Stronger data are needed to establish a cut-off for malignancy.