Hematology

	Answer 2 Figure. Aplastic anemia. The bone marrow sample shows no marrow elements and no evidence of dysplasia (Figure). This patient meets criteria for very severe aplastic anemia, with profound neutropenia (ANC < 200 cells/µL), thrombocytopenia (platelet count < 20,000 cells/µL), and marrow cellularity less than 25%. Work-up of aplastic anemia, including viral studies and thorough review of drugs, herbal products, and exposures to chemicals (eg, benzene) and radiation, is necessary. Most cases of aplastic anemia are idiopathic. In idiopathic aplastic anemia, the immune system is thought to cause the destruction of hematopoietic elements. As a result, treatment options include bone marrow transplantation or immunosuppression. The World Health Organization (WHO) criterion for acute leukemia is a blast count of over 20% in the marrow; this patient’s marrow has no evidence of an elevated blast count, making the diagnoses of acute lymphoblastic leukemia and AML unlikely. Also, in acute leukemias, the marrow is usually hypercellular as opposed to hypocellular. Typically, patients with MDS have an elevated cellularity in the bone marrow, and dysplasia is present in more than 1 cell line. However, it is often difficult to distinguish hypocellular MDS from aplastic anemia, particularly in older patients. To consider hypocellular MDS as a diagnosis, cytogenetic abnormalities and/or evidence of dysplasia on the bone marrow specimen should be present. Click here to return to the questions
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