RESUMEN
A 61-year-old man developed a rapidly progressive disease with anemia, thrombocytopenia and large number of blasts (10%) in the peripheral blood. The bone marrow revealed hypercellular marrow with extensive fibrosis and proliferation of immature cells of trilineage. Immunophenotyping and chromosome study with the bone marrow aspirate showed myeloblasts with aberrant expression of CD19 and complex karyotype including structural abnormalities within chromosome 5 and 7. After induction chemotherapy with Ara-c and daunorubicin, the number of blasts in peripheral blood was increased and the bone marrow showed hypercellular marrow with immature cells of trilineage and fibrosis. Cases like this have been called acute myelofibrosis, acute myelosclerosis or acute myelodysplasia with myelofibrosis. Recently this rare disease with rapidly fatal course was categorized into 'acute panmyelosis with myelofibrosis in acute myelogenous leukemia (AML) not otherwise categorized' by WHO classification.