Detection of chromosome 11q13 breakpoints by interphase fluorescence in situ hybridization - A useful ancillary method for the diagnosis of mantle cell lymphoma

We assessed cytologic specimens from 11 mantle cell lymphomas (MCLs) and 32 other B-cell non-Hodgkin lymphomas (NHLs) for 11q13 breakpoints using a 2- color fluorescence in situ hybridization (FISH) assay that uses an 11q13 pr obe centered on the CCND1 gene and a centromeric chromosome II probe (CEP11 ). The number of nuclei in 200 cells were counted, and results were express ed as an 11q13/CEP11 ratio. All MCLs showed a high percentage of interphase nuclei with 3 or more 11q13 signals (mean, 74.8%: range 57%-90%). In contr ast, in other B-cell NHLs the mean percentage of cells with 3 or more 11q13 signals was 9.2%. All MCLs had an elevated 11q13/CEP11 ratio (mean. 1.38). The mean ratio for other B-cell NHLs was 0.99. Two non-MCL cases, I large B-cell and I B-cell unclassified NHL, had high 11q13/CEP11 ratios of 1.15 a nd 1.30, respectively: Conventional cytogenetic analysis performed on the f ormer case revealed a t(5:11)(q31;q13). Interphase FISH analysis using 11q1 3 and CEP11 probes is a convenient ancillary method for assisting in the di agnosis of MCL. This commercially available assay is simple to use on cytol ogy or imprint specimens, and results can be obtained within 24 hours.