OCCURRENCE OF MULTIPLE MYELOMA AFTER FLUDARABINE TREATMENT OF A CHRONIC LYMPHOCYTIC LEUKEMIA: EVIDENCE OF A BICLONAL DERIVATION AND CLINICAL RESPONSE TO AUTOLOGOUS STEM CELL TRANSPLANTATION

BACKGROUND AND OBJECTIVES: The occurrence of chronic lymphocyte leukemia (CLL) and multiple myeloma (MM) in a single individual is rare and there is no consensus about the clonal relationship of the two disorders and no clinical data about the response to therapy. DESIGN AND METHODS: We describe a 49-year old patient who developed a III stage IgD k MM after fludarabine treatment for a previous diagnosis of CLL and then was submitted to an high-dose treatment with autologous CD34+ selected stem cell support. An immunologic and molecular characterisation of peripheral blood and bone marrow was performed at the time of appearance of the two coexisting neoplasms. RESULTS: By immunophenotyping, monoclonal B-lymphocytes stained with l chains, whereas marrow plasma cells were positive for k chains. The Ig heavy chain rearrangement analysis performed on the bone marrow confirmed the presence of two distinct tumour clones, one of which was also present in the peripheral blood. During an 18 months follow-up after autotransplantation, the CLL-related clone became undetectable, whereas MM persisted with a minimal amount of Bence Jones proteinuria and a 15-20% plasma cell marrow infiltration. INTERPRETATION AND CONCLUSIONS: Our results suggest that in this patient CLL and MM originate from separate B-cell progenitors. Both disorders were responsive to a CD34+ selected ASCT.