Immunostaining of galectin-3 and CD44v6 using fine-needle aspiration for distinguishing follicular carcinoma from adenoma

To evaluate the clinical applicability of galectin-3 and CD44 variant 6 (CD44v6) immunostaining in fine-needle aspiration cytology (FNAC) of thyroid follicular tumors, 79 cytological specimens (35 follicular carcinomas and 44 follicular adenomas) were studied. The positive rates of galectin-3 and CD44v6 were 89 and 74% in follicular carcinoma, respectively, and 25 and 30% in follicular adenoma, respectively. There were no significant correlations between the expression of galectin-3 or CD44v6 in follicular carcinoma and characteristics such as capsular invasion, vascular invasion, metastasis, or tumor size. Positive staining of either galectin-3 or CD44v6 resulted in a diagnostic sensitivity of 97% and a specificity of 52% for follicular carcinoma among follicular tumors. Immunostaining of galectin-3 or CD44v6 using cytological specimens can provide independent information on conventional morphological findings of cytology to distinguish follicular carcinoma from adenoma.