CD4 and acute myeloid leukemia: A subsequent bone marrow aspirate (Fig. 4) demonstrated a markedly hypercellular marrow with 69 % blasts, which by flow cytometry were identified as an abnormal population of myeloid cells expressing CD117, CD13, CD33, human leukocyte antigen-antigen D related (HLA-DR), CD123, lacking CD34, with aberrant CD4 expression, consistent with AML.