Three cases of multiple myeloma developing into melphalan-related chronic myelomonocytic leukemia

From 1980 to 1987, three cases of chronic myelomonocytic leukemia (CMML) were encountered among 68 cases of multiple myeloma who survived more than three years from the diagnosis. The incidence (4.8%) of secondary myelodysplastic syndrome (MDS) is almost identical to previous reports, but case reports of chronic myelomonocytic leukemia were rare. In Japan, there are few reports of multiple myeloma patients who later developed secondary MDS or acute myelogenous leukemia (AML). In our cases, none of the 31 patients treated with cyclophosphamide developed secondary MDS, while three of 37 patients treated with melphalan developed CMML. This difference is not statistically significant.