Dedifferentiated Chondrosarcoma: An Ultrastructural Study of Two Cases,with Immunocytochemical Correlations

The clinicopathologic features of two cases of dedifferentiated chondrosarcoma (DCS) are presented, in which anaplastic components showed the electron microscopic features of malignant fibrous histiocytoma, as well as immunoreactivity for alpha-1-antitrypsin and alpha-1-antichymotrypsin. Rare cells also displayed S100 protein in high-grade areas of the primary tumors, but a pulmonary metastasis lacked this determinant. These findings could be interpreted as reflecting a retained potential for primitive chondrogensis in primary DCS, which may be lost in its metastases. In all other respects, this tumor appears to assume the morphological and immunocytochemical attributes of a fibrohistiocytic neoplasm.