Acute myelomonocytic leukemia in a patient with multiple myeloma: evidence for different clonal origin.

A case of 77-year-old female with multiple myeloma (IgG-k) developed acute myelomonocytic leukemia (AMMoL) following a myelodysplastic stage after chemotherapy with melphalancyclophosphamide combinations for 6 years. The leukemic blast cells expressed both myeloid antigens (CD11b, CD13, CD14, CD15, CD33 and CD34) and T/B lymphoid antigens (CD2, CD4, CD22 and PCA1). Cytogenetic analysis revealed a chromosome deletion -7. Analysis of immunoglobulin genes showed the heavy chain genes in germ line configuration. These findings indicate that the AMMoL was a therapy-related stem cell leukemia and was a clonal origin genetically different from multiple myeloma irrespective of plasma cell phenotype.