[92] Ezrin Immunoexpression in Bone Sarcomas (Osteo-Chondrosarcomas and Ewing/PNET)

A Llombart-Bosch, I Machado, S Navarro, M Alberghini, F Bertoni. Valencia University, Valencia, Spain; The Rizzoli Orthopedic Institute, Bologna, Italy

Background: Ezrin is a cytoskeleton protein involved in metastatic development. Ezrin expression has been described in osteosarcomas and studies have recommended the utility of this protein as a tool to differentiate between chondrosarcomas and chondroblastic osteosarcomas (Salas S, de Pinieux G, Gomez-Brouchet A et al. Virchows Arch. 2009; 454(1):81-7). Ezrin expression in others bone tumors (Ewing/PNET) has been reported in isolated cases.
Design: A total of 397 bone tumors (33 osteosarcomas, 23 chondrosarcomas and 341 Ewing/PNET) were immunostained with ezrin antibody (clone 3C12, dilution 1:250). The immunoexpression was scored as negative; poor (+) moderate (++) strong (+++) cytoplasmic/membranous positivity.
Results: Chondrosarcoma showed low expression of ezrin (30%) and within the positive cases revealed predominantly high grade (Grade III) at histopathological level. Ezrin immunoexpression in osteosarcoma was high (69%), however chondroblastic osteosarcoma did not reveal ezrin expression; therefore, ezrin antibody probably cannot distinguish chondroblastic osteosarcoma from chondrosarcoma as proposed in previous publications. Ewing/PNET revealed ezrin expression in 40.7% of the tumors, with higher expression shown in atypical Ewing sarcoma (58.9%) and PNET (58.6%) compared with conventional Ewing (30%).
Conclusions: Ezrin immunoexpression is heterogeneous in bone tumors and immunostaining did not offer any diagnostic clue in the differential diagnosis of chondroblastic tumor. Additionally, Ewing/PNET frequently reveals ezrin expression. The protein expression seems to be associated with the histological grade, being higher in morphologically high-grade tumors. As previously reported, ezrin could be a molecular therapeutic target in bone tumors, but further studies are required to assess prognostic value. Support: EuroBonet (European network of excellence). Contract No. 018814
Category: Bone & Soft Tissue

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 26, Tuesday Morning


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