FISH analysis in chromophobe renal-cell carcinoma

Loss of chromosomes 1, 2, 6, 10, 13, 17, and 21 is a characteristic finding in chromophobe renal-cell carcinoma (ChRCC). Previously, cytogenetic and molecular genetic techniques were used in demonstrating the chromosomal monosomies in ChRCCs. We performed interphase fluorescent in situ hybridization (FISH) using centromeric probes for chromosomes 1, 2, 6, and 10 on touch imprint smears from six histologically proven ChRCCs. All six ChRCC tumors showed one FISH signal corresponding to one copy number for each of these chromosomes. The percent cells with one FISH signal ranged from 48-88% (chromosome 1), 36-89% (chromosome 2), 26-98% (chromosome 6), and 64-99% (chromosome 10). In addition, 3 of the 6 cases were further studied with centromeric probes for chromosomes 13, 17, and 21. All three revealed monosomy of these three chromosomes. We conclude that interphase FISH performed on touch imprint smears is a relatively simple, rapid, and reliable method for detecting chromosome abnormalities which are specific for ChRCCs.