Acute myeloid leukemia (AML) is a clonal hematopoietic neoplasm due to acquired oncogenic mutations that disrupts differentiation, resulting in the accumulation of immature myeloid blasts in the marrow. The marrow replacement by blasts results in marrow failure and complications related to anemia, thrombocytopenia and neutropenia. AML can affect all ages, but the incidence increases throughout life. AML is divided into four categories, one of which is AML with myelodysplasia-related changes. AML with myelodysplasia-related changes is a common type of AML in elderly patients. The diagnosis requires at least 1 of 3 following criteria: 1. Previous myelodysplasia or myelodysplastic/myeloproliferative neoplasm; 2. Dysplasia of > 50% of erythroid, megakaryocytic, and/or granulocytic lineage cells; 3. MDS-associated cytogenetic abnormality. Furthermore, the blast criteria for AML must be met (blasts/blast equivalents comprise ≥ 20% of nucleated peripheral blood and/or bone marrow cells), there should be no history of chemotherapy (alkylating agents, topoisomerase II inhibitor therapy) and/or radiotherapy or AML-defining cytogenetic abnormalities.

In this case, the bone marrow biopsy shows increased granulopoiesis and megakaryopoiesis. CD34 highlights 40-50% of blasts. The bone marrow aspirate is hypercellular with multilineage dysplasia in the form of dysplastic granulocytes and megakaryocytes. The flow cytometric pattern is also consistent with AML as the blasts express C13/33/34/117/38/71 and HLA-DR. MPO is positive. B and T cell markers are negative. The cytogenetic study shows monosomy 7. Monosomy 7 is sufficient for a diagnosis of AML with myelodysplasia-related changes according to the WHO 2008 classification in the absence of prior cytotoxic therapy. In the setting of AML, monosomy is associated with a relatively poor prognosis.

This slide shows the bone marrow aspirate. See Related Content for H&E & CD34 stains of the bone marrow biopsy.