Chromosome changes in sarcomatoid renal carcinomas are different from those in renal cell carcinomas.

Sarcomatoid renal carcinoma (SRC) is an uncommon and highly malignant renal tumor with sarcomatous morphology or with both sarcomatous and carcinomatous components. The tumors are generally referred to as dedifferentiated or transformed renal cell carcinomas (RCC). Information on their genomic changes is scarce. Data from a cytogenetic study of four cases of SRC are presented in this article. Combined with a few other cases from the literature, it appears that genomic changes in most cases of SRC have little in common with those characterizing conventional RCC. Sarcomatoid transformation thus may occur occasionally in RCC without the characteristic chromosome changes but also, and perhaps more frequently, in a subgroup of RCC without the characteristic chromosome changes.