Abstract
Chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) coexistence in the same patient has been rarely reported, more frequently due to treatment with chemotherapeutic agents. Blood parameter changes in cancer patients may be interpreted as disease progression or iatrogenic effects related to aggressive treatment, leading to delayed diagnosis. In our article, we call attention to the possibility of AML development in CLL patients and its diagnostic challenge.