Concomitant chronic lymphocytic leukemia and acute myeloid leukemia: evidence of simultaneous expansion of two independent clones.

The simultaneous appearance of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) has been rarely reported, with AML occurring more frequently as a secondary event in patients receiving cytotoxic drugs for a primary lymphoproliferative disorder. We describe a case of simultaneous CLL and AML documented by morphological and cytometric analysis in a previously untreated patient. In particular, on the basis of morphological and immunological features, the patient was diagnosed as being affected by CD34 + /CD13 + /CD33 + /HLA-DR + /CD7 + FAB-M2 AML, along with a B-CLL characterized by neoplastic cells expressing a VH3-53/D3-22/JH4 Ig, bearing, on average, 3.9% IgVH mutations without evidence of antigen-driven selection. To establish whether the two neoplastic cell populations shared some common molecular signature, we performed IgH gene rearrangement studies on CD34 + /CD19- and CD34-/CD19 + immunomagnetically sorted cell populations: only genomic DNA from the CD19 + /CD34- cell fraction revealed the presence of the IgH gene rearrangement. These results provide evidence that the rare concomitant association of CLL and AML likely arises from simultaneous expansion of two independent clones.