Development of myeloma and secondary myelodysplastic syndrome from a common clone

We report the case of a 49-year-old woman who presented with a monoclonally IgG kappa expressing myeloma since October 1989. Four years later, after 24 cycles of Melphalan-containing chemotherapy, bone marrow (BM) cells of the patient cytologically revealed myelodysplastic changes for the first time. Cytogenetic examination of the BM obtained in January 1994 showed two clonally aberrant main lines. Each of them represented one of the hematological neoplastic diseases. The quantitatively major clone (MDS-clone) showed a deletion of the long arm of chromosome 7, typical for secondary myeloid disorders. The other clone (myeloma (MM) clone) was characterized by a reciprocal translocation between the short arm of chromosome 8, band q24, a region known to contain the c-myc gene, and the long arm of chromosome 2, band p12, where the Ig kappa gene is located. An unusual finding, however, was that an abnormality of the long arm of chromosome 16 could be detected in both obviously unrelated clones. In the further course of the disease, the MDS and MM clones could be detected, both of them showing cytogenetically a clonal evolution characterized by additional clonal abnormalities. Our data stress the significance of cytogenetics in detecting typical clonal abnormalities in different malignant hematological disorders and in detecting "clonal evolution" as an indicator of the progress of the disease. Moreover, our data suggest that MM and MDS may arise from a common stem cell, which may be characterized by a clonal cytogenetic abnormality.