Galectin-3 and CD44v6 positivity by RT-PCR method in fine needle aspirates of benign thyroid lesions

To investigate whether the presence of macrophages and Hürthle cells (HC) in benign thyroid lesions could explain the false-positive expression of galectin-3 and CD44v6 detected by reverse transcriptase-polymerase chain reaction (RT-PCR).

For galectin-3 and CD44v6, RT-PCR was performed on RNA isolated from aspirates obtained by ultrasound guided fine needle aspiration cytology (FNAC) from 123 patients with benign thyroid lesions. The results of RT-PCR analysis were evaluated against the definitive FNAC diagnosis.

Galectin-3 expression was found in 29% follicular adenoma (FA), 26% Hashimoto thyroiditis (HT), and in 24% nodular goitre (NG). We found a statistically significant relationship between the presence of macrophages and galectin-3 positivity in NG and HT samples (P < 0.0001 and P = 0.0087 respectively). We found a statistically significant (P = 0.0219) relationship between the presence of HC and galectin-3 positivity in HT and a tendency of such a relationship (P = 0.0838) in NG. CD44v6 expression was found in 29% FA, 33% HT and in 18% NG. We found a statistically significant relationship between the presence of HC and positive expression of CD44v6 in NG (P = 0.0003) and a strong tendency of such a relationship in HT (P = 0.0571). We did not find a statistically significant relationship between the presence of macrophages and CD44v6 positivity. In FA, we did not find a statistically significant relationship between the presence of macrophages or HC and galectin-3 or CD44v6 positivity.

Our results suggest that the presence of macrophages and/or HC may explain the positive expression of galectin-3 and CD44v6 detected by RT-PCR in HT and NG cytological samples.