[A case of vesical carcinoma with sarcomatous changes--immunohistochemical and electron microscopic observations].

The immunohistochemical and electron microscopic characteristics of a vesical carcinoma with a sarcomatous change in a 90-year-old man are described. Keratin was strongly positive in the carcinomatous region and was also identified in the sarcomatous region. CEA was present only in the carcinomatous region. Both the carcinomatous and sarcomatous regions were negative for S 100 protein, myoglobin, lysozyme, and desmin. Electron microscopically, a few tumor cells with tonofilaments were observed in the sarcomatous region. Many tumor cells in the sarcomatous region had no characteristic structures suggestive of epithelial or mesenchymal origin. However, transitional types of tumor cells, between the epithelial cells and the cells with neither epithelial nor mesenchymal differentiation, were noticed. Therefore, this suggested that the sarcomatous region was a site of immature epithelial cell proliferation.