[Renal cell carcinoma with a spindle-cell element--sarcomatous or sarcomatoid?]. / Renaalselkarsinoom met 'n spoelvormige selelement--sarkomateus of sarkomatoïed?

In this study the light microscopic and electron microscopic findings in two renal cell carcinomas with spindle-cell elements are described. The ultrastructural features of the spindle-cell element of sarcomatoid renal cell carcinoma have previously been documented, namely pentalaminar desmosomes, basal lamina formation and intracytoplasmic lumina with microvilli. The electron microscopic findings in the 2 cases described here showed mesenchymal rather than epithelial differentiation. It would appear that some renal cell carcinomas with a spindle-cell element are true carcinosarcomas, rather than sarcomatoid renal cell carcinoma.