Peripheral Blood Blast Erythrophagocytosis After Chemotherapy in a Patient with Acute Monoblastic Leukemia

Abstract

Hemophagocytosis is a property of histiocytic lineage cells; it is rarely performed by leukemic blasts. This phenomenon happens in approximately 1% of acute leukemias, particularly acute myeloid leukemia (AML) and especially those of monoblastic or monocytic lineage. Associations have been found with some chromosomal abnormalities, especially t(8;16). The presence of blast hemophagocytosis may speed-up the diagnosis of some of these cytogenetic abnormalities. We aim to report a case of peripheral blood blast erythrophagocytosis after chemotherapy for the treatment of acute monoblastic leukemia. It is about 29 years old male treated for acute monoblastic leukemia without chromosomal abnormalities at the onset, with two relapses for the first and second induction cures. Peripheral blood smear performed during the follow up showed 73% of blasts, 3.6% of them with erythrophagocytosis. Several genetic abnormalities are known to be associated to leukemic cell hemophagocytosis, involving particularly the chromosome 8 and explaining a part of the leukemogenesis. These abnormalities are rare and associated to a poor prognosis. The mechanism behind this blast behavior is still unclear and authors suggest some hypothesis to explain this phenomenon: the presence of binding receptors involved in phagocytosis on blasts, karyotype instability and evolution during the course of the disease and the involvement of treatment toxicity.