Chordomalike soft tissue sarcoma in the leg: a light and electron microscopic and immunohistochemical study.

A soft tissue tumor in the leg of a 67-year-old woman is described. This large tumor below the knee area infiltrated extensively the deep and superficial soft tissues but did not involve the bones. The tumor cells formed nodules resembling the architecture seen in chondroid tumors and chordoma. The tumor cells were often vacuolized, and there was extracellular myxoid matrix similar to that in chordoma or myxoid chondrosarcoma. Immunohistochemistry showed keratins 8 and 19, epithelial membrane antigen, and vimentin in most tumor cells, and there was also S-100 protein positivity in a number of tumor cells. Electron microscopy showed desmosomelike cell junctions and bundles of intermediate filaments resembling those seen in many epithelial neoplasms. Thus the tumor resembled chordoma in many respects. Because clinically no other primary tumor was found, this tumor is probably a chordomalike primary soft tissue sarcoma different from typical extraskeletal myxoid chondrosarcoma or chordoid sarcoma.