The morphologic findings are of acute myelogenous leukemia. Flow cytometric data are also consistent with acute myelogenous leukemia, but in addition flow cytometric studies detect the presence of a lymphoproliferative process, chronic lymphocytic leukemia (CD5+/CD19+). The morphologic findings of abundant basophils in the bone marrow aspirate suggests that a chronic myelogenous leukemia presenting in blast crisis should be ruled out by cytogenetic and/or molecular studies. The association of acute myelogenous leukemia to chronic lymphocytic leukemia has been previously described.
The morphologic findings in this 68 year-old woman are consistent with the rare occurrence of concomitant acute myelogenous (AML) and chronic lymphocytic leukemia (CLL) confirmed by the flow cytometric analysis. The diagnosis of AML-M2 rests upon the bone marrow findings of marked hypercellularity, >30% blasts, >3% myeloperoxidase positive blasts, > 10% granulocytic cells which have matured beyond the blast stage, and <20% monocytic cells. Flow cytometric immunophenotypic studies performed on the bone marrow aspirate demonstrate a CD13,33+/CD34+, CD15+, HLA-DR+, myeloperoxidase positive large non-complex cell population (48% of events).
The possibility that the AML in this case represented CML in blast crisis was considered due to the relatively increased number of basophils in several bone marrow particles. However, genotypic and cytogenetic studies, did not demonstrate the Bcr-abl translocation thus making the diagnosis of blast crisis less likely.
The diagnosis of concomitant CLL in this case was based upon absolute lymphocytosis in the peripheral blood and bone marrow aspirate flow cytometric immunophenotypic findings of monoclonal kappa positive B-cells which coexpressed CD19 and CD5 and had weak surface immunoglobulin. Cytogenetic and FISH studies performed on interphase cells did not reveal evidence for trisomy 12.
The simultaneous presentation of AML and CLL has been noted in a small number of reports. AML may also occur following treatment of CLL with chemotherapeutic agents. Flow cytometric immunophenotypic studies has been shown previously to aid in the diagnosis of concomitant AML and CLL and proved beneficial in this case. In the rare cases of simultaneous presentation, symptomatology due to the presence of AML may lead the patient to seek medical attention, subsequently leading to the discovery of coexistent indolent asymptomatic CLL. The development of other malignancies in patients with CLL has been shown to occur and is possibly due to the decreased immune competence reported in these patients. Some authors hypothesize that the simultaneous occurrence of AML and CLL may be due to a common stem cell defect or leukemogenic factor or possibly a genetic susceptibility in some patients. Concomitant AML and CLL occurring due to chance cannot be excluded. Regardless of the etiology, complete remission of simultaneous AML and CLL, demonstrated immunologically, was achieved in one case report. In this case, the patient's latest BMBx at 1 month following induction chemotherapy demonstrated residual chronic lymphocytic leukemia by flow cytometric immunophenotypic studies, although acute myelogenous leukemia was not identified.
Contributed by Valerie A. Holst, MD, Lila S. Penchansky, MD, and Charles A. Richert, MD