High incidence of chromosome 1 abnormalities in a series of 27 renal oncocytomas - Cytogenetic and fluorescence in situ hybridization studies

Context.-It has recently been shown by cytogenetics that there is a high incidence of chromosome 1 abnormalities in renal oncocytomas. Objective.-To confirm the cytogenetic results by fluorescence in situ hybridization (FISH) analysis. Design.-Nine additional cytogenetic analyses were added to those reported in our recent study, with a total of 27 tumors studied, which makes it the largest series of renal oncocytomas studied to date by cytogenetics and/or FISH. We used the LSI 1p36/LSI 1q25 Dual Color Probe Set to make the analyses. Results.-In this study, combined cytogenetics and FISH showed loss of chromosome arm 1p1 in 48% of renal oncocytomas. By FISH, deletion of 1p36.3 was observed in 59% of renal oncocytomas, whereas by cytogenetics, abnormality in chromosome 1 was seen in 32% of tumors. However, the incidence of chromosome 1 abnormalities among 9 bilateral tumors was much higher than in single tumors (88% vs 28%, respectively). Loss of only the 1p36.3 site occurred in 2 renal oncocytomas with translocation of chromosome 1, as shown by cytogenetics. Concordance between the 2 techniques, when they were used simultaneously to detect chromosome 1p1 abnormality, was 82%. Conclusions. This study further confirmed our prior results demonstrating the widespread occurrence of chromosome 1 abnormalities in renal oncocytomas. Although no abnormalities in chromosome I in tumors with normal karyotypes were detected by FISH using the current set of probes, a much higher incidence of such abnormalities was found in bilateral tumors, suggesting that genetic alterations related to the development of renal oncocytoma reside in this region.