Multiple myeloma exhibiting production of IgD M-protein is a rare subset (appr. 1 %) of all patients. Translocation t(11;14) is, on the other hand, the most common primary translocation in myeloma that involves the IgH locus and cyclin D1, approximately 16–22% of all patients harbor this genetic rearrangement. This cytogenetic abnormality has been previously associated with nonsecretory behavior and also with production of IgE M-protein. Out of 317 myeloma patients treated in our department in 2004–2006, five patients had IgD M-protein (four belonged to IgD-lambda and one to IgD kappa subtype). Cytogenetic analysis by interphase fluorescent in situ hybridization (FISH) revealed the presence of the IgH/Cyclin D1 abnormality in all five of them (100%), while the prevalence of this translocation was 17% in the entire myeloma population seen by our ward and tested by FISH (132 patients). One IgD patient had a complex IgH/MYC/CyclinD1 translocation, also confirmed by conventional cytogenetic analysis of metaphases, while two of five patients had additional copies of IgH and Cyclin D1 genes, possibly indicating atypical translocations and/or hyperdiploidy. Although the number of patients with this rare disease in our report is low (5), we find the uniform presence of translocation t(11;14) a striking occurrence that may explain some of the unusual biological properties of this myeloma subtype.

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