Specific genetic changes of diagnostic importance in chromophobe renal cell carcinomas.

The histologic diagnosis of chromophobe renal cell carcinomas is often uncertain because of phenotype overlap among different types of kidney cancers. Recently, in a novel genetic classification of renal cell tumors, a combination of monosomies of chromosomes 1, 2, 3, 6, 10, 13, 17, and 21 have been suggested to have a diagnostic value for this unique type of tumor. Therefore, we have analyzed fresh and paraffin-embedded tissues obtained from 42 chromophobe renal cell carcinomas for allelic losses at the above-mentioned chromosomal regions by employing microsatellite markers. Loss of chromosomes 1, 2, 6, 10, 13, and 17 was detected in between 75% and 95% of tumors, and loss of chromosome 21 was observed in 54% of cases. All but one tumor showed a combination of monosomies at the specific chromosomes. Thus, applying the set of microsatellite markers used in this study, a PCR-based diagnosis of chromophobe renal cell carcinomas could be established within 1 to 2 days. The general applicability of this approach to fresh and paraffin-embedded tissues allows a correct genetic characterization in all cases where a diagnosis based on histopathology remains uncertain.