Aim: We aimed to evaluate four immunohistochemical markers (HBME-1, Galectin-3, Cytokeratin-19 and CD56) used alone or in panels in a series of papillary thyroid carcinoma (PTC) and thyroid tumors of uncertain malignant potential (TT-UMP) cases.
Materials and methods: We performed an immunohistochemical analysis on a tissue micro-array of 11 PTCs [six classic (CPTC), five follicular variant (FVPTC)] and 31 TTs-UMP. A control group of 11 benign thyroid lesions/tumors was also included.
Results: CD56, whose expression is reduced or absent in thyroid carcinomas, was the most sensitive marker (81.8%), showing a "malignant" profile in 5/6 CPTCs and 4/5 FVPTCs. It was followed by HBME-1 (63.6% sensitivity). Cytokeratin-19 and Galectin-3 were the least sensitive antibodies (45.6%), but the most specific ones (100%). Three panels consisting of CD56 and/or Cytokeratin-19/Galectin-3 and HBME-1 and/or CD56 reached the highest sensitivity (90.9%) and the highest negative predicting value (87.5 and 83.3, respectively). In TTs-UMP, Cytokeratin-19, Galectin-3, HBME-1 and CD56 stained negatively in most of the cases (90.3%, 83.9%, 87.1% and 61%, respectively) and no statistically significant differences compared to the benign thyroid lesions' immunoprofile could be observed.
Conclusions: New panels of antibodies, consisting of CD56 and/or Cytokeratin-19/Galectin-3 and CD56 and/or HBME-1 that were found to be highly sensitive for PTC in our study, are reported. Applying these panels to TTs-UMP seems also useful. Our results showed that these tumors have an immunoprofile similar to the benign thyroid lesions, suggesting that they are most likely to have a benign rather than a malignant biological behavior.