Differences in genetic changes between multiple myeloma and plasma cell leukemia demonstrated by comparative genomic hybridization

Abstract

To analyze the genomic differences between multiple myeloma (MM) and plasma cell leukemia (PCL), a total of 30 cases were studied by comparative genomic hybridization (CGH). In five cases with a low proportion of plasma cells (PC) in bone marrow, an enrichment of PC was performed by using immunomagnetic beads conjugated with the monoclonal antibody B-B4. In 24 out of the 25 MM (96%) and in all five PCL (100%) patients DNA copy number changes were identified by CGH analysis; in the MM case without chromosomal imbalances, the immunomagnetic enrichment of PC had failed. The most recurrent changes in MM patients were gains at chromosomes 15q (48%), 11q (44%), 3q (40%), 9q (40%) and 1q (36%). By contrast, all PCL patients showed gains in 1q. Losses of chromosomal material were significantly more frequent in PCL than in MM patients (P = 0.03): losses on 13q in 80% of PCL vs 28% of MM; and on chromosome 16 in 80% vs 12%, respectively. In addition, PCL patients showed losses of 2q and 6p that were not present in MM. The CGH data show differences in chromosomal imbalances between MM and PCL.