The hallmark of chromophobe renal cell carcinoma is multiple chromosomal losses from among chromosomes 1, 2, 6, 10 and 17. Chromophobe renal cell carcinoma with distant metastases or sarcomatoid transformation are uncommon and little is known about their chromosomal abnormalities. We collected six sarcomatoid chromophobe renal cell carcinomas and three primary chromophobe renal cell carcinomas with distant metastases. A cytogenetic analysis by fluorescent in situ hybridization on paraffin-embedded tissue was performed using centromeric probes for chromosomes 1, 2, 6, 10 and 17. We found more than one signal in four of six (66%) sarcomatoid chromophobe renal cell carcinomas, in both sarcomatoid and adjacent epithelial components. Both primary chromophobe renal cell carcinomas and matched metastases showed single signals for all chromosomes studied in two cases and no abnormalities in the remaining case. We concluded that: (1) both epithelial and sarcomatoid components of sarcomatoid chromophobe renal cell carcinoma show different genetic abnormalities from those characteristic of chromophobe renal cell carcinoma; (2) sarcomatoid chromophobe renal cell carcinomas frequently have multiple gains (polysomy) of chromosomes 1, 2, 6, 10 and 17; (3) distant metastases show the same genetic patterns, usually chromosomal losses (monosomy), found in the primary tumors. Keywords: sarcomatoid chromophobe renal carcinoma; metastases; FISH; cytogenetic Most chromophobe renal cell carcinomas are low stage, cured by surgery and have a relatively good prognosis. 1 Losses of chromosomes 1, 2, 6, 10 and 17 are frequent genetic abnormalities in both classic and eosinophilic chromophobe renal cell carcinomas. 2 Chromophobe renal cell carcinomas with distant metastases or sarcomatoid transformation are uncommon. [3][4][5][6] Most have been reported as single cases [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and few cytogenetic data are available. 24 We sought to identify cytogenetic characteristics of sarcomatoid and metastatic chromophobe renal cell carcinomas by interphase fluorescence in situ hybridization (FISH) analysis.
Materials and methods
Tissue Samples, Histochemical and Immunohistochemical AnalysesWe collected six chromophobe renal cell carcinomas with sarcomatoid transformation and three primary chromophobe renal cell carcinomas with matched distant metastases. Two cases with sarcomatoid features were collected from the