[Osteosarcoma cell immunophenotype and heterogeneity]

48 cases of osteosarcoma, including 18 cases of osteoblastic type, 16 of fibroblastic type and 14 of chondroblastic type, were studied in accordance with Dahlin's classification. All specimens were stained with 11 specific markers using immunohistochemical ABC methods. Positive immunostaining for BMP was found in all of these cases. The results showed 48 vimentin positive cases, 46 actin positive cases, 5 keratin positive cases and 4 desmin positive cases. Neither cytokeratin nor EMA was identified in any of the cases. Positive reactions to S-100 protein, collagen type IV, UEA-1 and factor XIII were observed in 26, 20, 36 and 13 of the cases respectively. The results of this study confirm that osteosarcoma possesses the unique multidirectional differentiation potential toward osteoblastic, chondroblastic, myofibroblastic, fibrohistiocytic and epithelial cells, and also indicate that immunophenotypic analysis is useful for the diagnosis, differential diagnosis and classification of the tumor cells of osteosarcoma.