Galectin-3 Is Not an Universal Marker of Malignancy in Thyroid Nodular Disease in Children and Adolescents

Current methods of research into thyroid nodular disease (TND) based on the polymerase chain reaction (PCR) and reverse-transcription (RT) permit the detection of some markers, even in poorly cellular biological material. The findings from fine-needle aspiration biopsy (FNAB), the most commonly used procedure in TND, do not always correlate with the postoperative histopathological diagnosis, sometimes giving a false negative result. The aim of this present study was to improve the classical cytological evaluation of the material obtained with ultrasound-guided biopsy with a RT-PCR based technique in order to detect carcinoma even in a minimally invasive form. Aspirate from the 30 patients included in the study was smeared for conventional cytology (H+E and MGG staining) and the leftover material in the needle was frozen for subsequent PCR analysis. Fine-needle aspiration specimens were evaluated for the presence of galectin-3 (GAL-3), the most promising molecular marker of malignancy. As a positive control for cells of follicular origin, thyroglobulin (Tg) gene expression was performed. RT-PCR was performed on extracted RNA and with specific primers for the screened genes, based on a one-step reaction with a Biometra PCR machine. Tg expression was observed in 23 aspirates, among which 10 were positive for the expression of GAL-3 [3 cases of PTC, 1 an oxyphilic variant of FTC, 1 an oxyphilic variant of follicular adenoma (FA), 1 a foetal variant of FA, 2 of Hashimoto thyroiditis (HT) and 2 of HT with coexisting FA]. Our results are the first evidence that GAL-3 expression, previously documented in thyroid carcinoma of follicular origin, is also present in Hashimoto thyroiditis. This study reveals some limitations in nodule or multiple nodules of benign character. If the diagnosis of HT is excluded, then the usefulness of the method in the diagnosis of malignancy may still be very high.