The Expression Of Galectin-3 In Fallicular Thyroid Tumors And Its Clinical Significance

Background: Follicular thyroid tumors(FTT) include thyroid follicular carcinoma(FTC), thyroid atypical adenoma(ATA) and thyroid follicular adenoma(FTA). Pathologic diagnosis is the golden standard for FTT. However, the differential diagnosis of FTT must base on entire thickness, infiltration of the capsule and vascular invasion, not the tissue structure, cytologic atypism or nuclear mitotic figure. With the development of IHC, it is necessary to search a sensitive and specific marker of FTT to improve the pathologic diagnosis. Galectin-3, a member of galectins family, is a kind of beta-galactoside-binding proteins. It has been suggested to play an important role in some physiological and pathological processes, such as pre-mRNA splicing, cell-cell and cell-matrix adhesion, cell growth, neoplastic transformation, metastasis and immune response. Recently, the expression of galectin-3 in fallicular thyroid tumors and its clinical significance has become a hot topic in pathology.Objective: To explore the important significance of galectin-3 in the diagnosis of FTT.Methods: 88 patients diagnosed as FTT in the Third Hospital of JiLin University from 2005 to 2006 were enrolled in this research retrospectively. They were all divided into three groups of FTC, ATA and FTA. The group of FTC(50 patients) was also divided into some subgroups according to the difference of benign lesions around carcinoma, malignancy, invasion, differentiation, histopathological types, metastasis of lymph node and age and gender of the patients. The expression of galectin-3 in all the patients was measured by immunohistochemistery in our research. Furthermore the relationship between the expression of galectin-3 and the biological characters such as the growth, invasion and metastasis was also analyzed.Results: (1) The expression of galectin-3, which was localized mainly in cytoplasm and nuclei, was higher in 50 follicular thyroid carcinoma(with the positive expression rate of 98.0%). But the positive expression rates in 36 nontumorous benign lesion and 26 tumour benign lesion were 0 and 34.62% respectively. The positive expression rate of galectin-3 in FTC was much higher than that in benign lesions (χ2 test, P<0.01). (2) The expression rate of galectin-3 in ATA(91.67%) was higher than FTA(34.26%) significantly (χ2 test, P < 0.05) while there was no significant difference between ATA and FTC(98.0%). (3) The middle-strong positive expression rate of galectin-3 in positive expressed well-differentiated FTC was 86.36% and 40.74% in positive expressed middle-poorly differentiated FTC. There was significant difference between well and middle-poorly differentiated FTC(χ2 test, P<0.05) and no relationship between the differentiation and the positive expression rates of galectin-3 in FTC (χ2 test, P>0.05). (4) The positive expression rate of galectin-3 in extensive invasion FTC was 97.22%, but that in minimally invasive follicular was 100.0%(χ2 test, P > 0.05), it suggested that there was no relationship between the positive expression rate of galectin-3 and invasion in FTC. (5) The positive expression rates of galectin-3 in clear cell type, intermediate type and eosinophilic cell type FTC were 100.0%, 96.88% and 100.0% respectively. It suggested that the positive expression rate of galectin-3 in FTC had no relationship to the histopathological types of FTC(χ2 test, P>0.05). (6) The positive expression rate of galectin-3 in FTC with lymph node metastasis was 90.0%, but that in FTC without lymph node metastasis was 100.0%(χ2 test, P>0.05), it demonstrated that the positive expression of galectin-3 in FTC would not be influenced by lymph metastasis. (7) The positive expression rate of galectin-3 in FTT has no relationship with patient's gender or age.Conclusions: (1) Galectin-3 was commonly high expressed in FTC and negatively in benign lesions. It may be a reliable maker for presurgical diagnosis of FTC. (2) The expression of galectin-3 may be useful to the differential diagnosis of ATA and FTA. (3) Galectin-3 seems not to be an useful marker for the distinction between FTC and ATA. (4) There is no relationship between the expression of galectin-3 and the differentiation of FTC, but there is direct or indirect correlation between middle-strong expression of galectin-3 and the differentiated or malignant degree of FTC. (5) There were no relationship between the expression of galectin-3 and the histopathological types, the invasion degree and the lymph metastasis in FTC.