Concomitant chronic lymphocytic leukemia and acute myeloid leukemia with an uncommon immunophenotype

We report a case of simultaneous diagnosis of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML), in which the use of flow cytometry analysis allowed the demonstration of two different cell populations and the study of both immunophenotyping patterns with a large panel of monoclonal antibodies (MoAbs). CLL cells showed a typical immunophenotype with coexpression of B cell markers with CD5, CD23, CD43, and weak surface immunoglobulin light chain restriction expression, whereas the AML population had a very uncommon phenotype with expression of myeloid markers and CD56 and lack of expression of other natural killer (NK) antigens, CD34 and HLA-DR. After chemotherapeutic treatment of AML with two induction courses, the patient achieved complete remission of the AML with persistence of a CD19/CD5 positive population. After consolidation chemotherapy, this latter population was no longer detectable despite the presence of lymphoid nodules in a bone marrow biopsy. Six months after diagnosis, the patient relapsed with AML and died shortly afterwards.