Galectin-3 and HBME-1 expression in oncocytic cell tumors of the thyroid

Oncocytic cell tumors (OCTs) of the thyroid include oncocytic cell adenomas (OCAs) and oncocytic cell carcinomas (OCCs). Oncocytic variant of papillary carcinoma (OVPC) has also been described. These tumors may present similar diagnostic problems as their non-oncocytic counterparts, in both conventional histology and fine-needle aspiration biopsies. Several markers were shown able to distinguish benign from malignant thyroid follicular tumors, galectin-3 and HBME-1 being the most promising ones. Controversial data have been reported on their discriminatory potential in the small series of OCTs so far analyzed. We aimed to assess the role of galectin-3 and HBME-1 in a large series of 152 OCTs (including 50 OCAs, 70 OCCs and 32 OVPCs). The expression of PPAR protein was also evaluated. Using a biotin-free detection system, the sensitivity of galectin-3 was 95.1%, while that for HBME-1 was nearly 53%. The combination of galectin-3 and HBME-1 increased the sensitivity up to 99%. However, for both markers, the specificity was 88%, lower than that reported for non-oncocytic follicular tumors. PPAR protein overexpression was absent in all OCAs tested and present in only 10% of OCCs, confirming previous reports on the low prevalence of PAX8-PPAR translocations in OCT and ruling out its role as a potential diagnostic marker of malignancy.