Background :Acute panmyelosis with myelofibrosis categorized by WHO classification is a rare disease characterized by a rapid clinical course and hypercellular marrow with extensive myelofibrosis and proliferation of immature cells of trilineage. We describe a 73-year-old male with myelofibrosis and panmyelosis occuring in primary myelodysplastic syndrome (MDS). Six years ago, he had an operation for spinal lipomatosis, and three years later, the cause of his thrombocytopenia was diagnosed as MDS after a bone marrow examination. On admission, immature cells in the peripheral blood were increased and a bone marrow biopsy revealed myelofibrosis and a cluster of hypolobulated and/or nonlobulated megakaryocytes with 100% cellularity. Method : Result : Conclusion :

Keywords: Myelofibrosis, Myelodysplastic syndromes