Immunohistochemical expression of RANK, GRalpha and CTR in central giant cell granuloma of the jaws.

The aim was to evaluate the phenotypic expression of various cellular osteotropic factors in central giant cell granuloma (CGCG). Paraffin-embedded tissue from 27 aggressive and 10 non-aggressive cases of CGCG was assessed for the expression of RANK, GRalpha and CTR using immunohistochemistry. In addition, a staining-intensity-distribution (SID) score (proportion of stained cells x staining intensity) was used to assess immunoreactivity of each marker. The results showed that the multinucleated giant cells (MGC), mononuclear stromal cells (MSC) and endothelial cells were intensely positives for GRalpha, moderate for RANK and weak-to-moderate for CTR in all clinical groups, whereas spindle-shaped cells were intensely immunoreactive to GRalpha and unreactive to CTR and RANK. Although neither difference in RANK and GRalpha expression nor the SID score between the clinical forms of CGCG was observed, a statistically significant difference for CTR was evident. Furthermore, the comparison of the marker expression and SID score showed a significant correlation for all three markers within the clinical groups, except for GRalpha in the non-aggressive lesions where a weak and no significant correlation was detected. It was concluded that although the MGC share some similarities with the osteoclasts, they demonstrate phenotypic differences from each other that suggest a distinct precursor. The expression of RANK, GRalpha and CTR also suggest a role for these receptors in the resorptive activity of different cellular groups in CGCG and may lead to a more effective use of therapeutic inhibitors of bone resorption for the treatment of these disorders.