Renal cell carcinoma: comparison of morphological and flow cytometric parameters of primary tumour and invasive tumour lying within the renal vein.

Histological assessment and DNA flow cytometry have been performed on 15 kidneys containing primary adenocarcinomas which had invaded the renal vein. Comparison of morphological variables showed that samples of the intravenous tumour were more commonly composed of granular cells (53 per cent) than were samples from the main tumour mass (16 per cent), and were also of higher nuclear grade. In 7 of 14 kidneys, DNA studies showed either a higher S-phase fraction (five cases) or DNA aneuploidy (two cases) in tumour cells lying within the renal vein. The mean S-phase fraction was also shown to increase in higher nuclear grades. Thus, both morphological and biological differences exist between invasive tumour cells lying within the renal vein and those in the main tumour. This is a useful model for the investigation of venous invasion and may give a better prediction of the metastatic potential of renal cell carcinoma.