Detection of translocation t(11;14)(q13;q32) in mantle cell lymphoma by fluorescence in situ hybridization

To assess an unequivocal diagnosis of mantle cell lymphoma (MCL), we have d eveloped a fluorescence in situ hybridization (FISH) assay, enabling the de monstration of t(11;14)(q13;q32) directly on pathological samples. We have first selected CCND1 and IGH probes encompassing the breakpoint regions on both chromosomes. Then, we have defined experimental conditions enabling us to obtain bright clear-cut signals Ln all of the samples, independently of the initial fixation conditions. We have analyzed single-cell suspensions from 26 formalin-fixed, paraffin-embedded MCL samples with this set of prob es. In all cases, we have found a fusion signal (ie, a t(11;14)(q13;q32) tr anslocation) in 14% to 99% of cells (median, 87%). So far, IGH-CCND1 fusion s have been detected in all of the 51 MCL patients that we have analyzed by FISH (either on paraffin-embedded tumor samples or on peripheral blood sam ples). Regarding the low sensitivity of other techniques used to diagnose t (11; 14)(q13;q32) (ie, 70% to 75% for cytogenetics and 50% to 60% for polym erase chain reaction), our FISH assay is by far the most sensitive techniqu e. Moreover, because of the quality of the fluorescent signals and the rapi dity of the experiment, this technique is widely applicable, even in routin e cytogenetics or pathology laboratories. As MCL patients are usually refra ctory to standard therapy, an unambiguous diagnosis is needed to propose ad apted therapeutic strategies, and this highly sensitive assay may be of gre at value for accurate diagnosis in difficult cases.