Poster session n. 2

Abstract # 570: RANKL and RANK Expression in GCTB: an Immunohistochemical Study M Roudier, et al, Amgen Inc. Giant cell tumor of bone (GCTB) results in osteoclast-mediated osteolysis. RANKL, via its receptor RANK, is essential for osteoclast formation, function and survival. OPG is a soluble decoy receptor for RANKL and a physiological inhibitor of RANKL function. We used immunohistochemistry to evaluate RANK, RANKL, and OPG expression in a series of archival GCTB specimens.

Results and Conclusions RANKL was expressed in spindle-shaped cells with one or two nuclei in all GCTs. RANK was expressed in pauci- and multinucleated cells in all GCTs. OPG was observed on both types of cells in all GCTs. RANKL expression in spindle-shaped cells suggests that these cells are of osteoblast lineage. The pauci- and multinucleated RANK-expressing cells are likely to be reactional to the RANKL-expressing cells. RANKL expression in spindle cells suggests that treatment with RANKL inhibitors may eradicate the lytic component of the tumor and may provide a treatment for unresectable GCTB.

The Clinicopathologic Significance of Macrophage Migration Inhibitory Factor (MIF) Expression in Osteosarcoma MIF (macrophage migration inhibitory factor) Cytokine involved in many immune responses implication in angiogenesis, tumor growth, invasion and metastasis Purpose To investigate the expression of MIF and its clinicopathologic significance in osteosarcoma Materials and methods 58 osteosarcoma patient samples Immunohistochemistry

Results & Summary MIF expression : 64% (Gr 1 and Gr 2 staining) Metastasis developed in 19% of Gr 0, 38% of Gr 2 and 67% of Gr 3 patients. Correlation of MIF expression and the development of distant metastasis. (p=0.005) 5 year survival 89% in Gr 1, 84% in Gr 1, 34% in Gr 2 Significantly low survival rates in Gr 2 patients (p=0.001) Correlation of MIF expression with overall survival in osteosarcoma MIF was an independent prognostic factor in osteosarcoma.