Differential expression of galectin-3 in medullary thyroid carcinoma and C-cell hyperplasia

OBJECTIVE AND DESIGN Galectin-3 is a beta-galactoside-binding protein that plays a role in cell adhesion and tumour progression. It was shown recently to diagnose malignant follicular thyroid lesions accurately. The reliability of this marker in the differential diagnosis between medullary thyroid carcinoma and C-cell hyperplasia was studied by immunohistochemistry. PATIENTS Tissue specimens were obtained from 34 patients belonging to families with medullary thyroid carcinoma who underwent prophylactic thyroidectomy for RET gene mutation and/or abnormally increased plasma calcitonin levels. RESULTS Galectin-3 was expressed in 23 of 25 cases of medullary thyroid carcinoma and in none of the nine cases of C-cell hyperplasia only, giving a sensitivity of 92% and a specificity of 100% for the diagnosis of carcinoma. A significant association was found between higher galectin-3 expression and occurrence of lymph node metastases ( P < 0.05). CONCLUSIONS Galectin-3 is a reliable diagnostic marker of medullary thyroid carcinoma, and its use may provide relevant information for prognosis and therapy.