Atypical infiltration of megakaryocytes into the liver and spleen in a case of refractory anemia

A 72-year-old man was admitted to our hospital because of general malaise. The peripheral blood showed pancytopenia (WBC 800/microliters, RBC 970,000/microliters, Plt 95,000/microliters). The bone marrow smear revealed morphological abnormalities in three lineage without increase in blasts. He was diagnosed as having myelodysplastic syndrome (MDS). He was treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF) for leukopenia, and with washed RBC transfusions for anemia. Eight months after diagnosis of MDS, blastic cells increased in peripheral blood and bone marrow showing overt leukemic state. He died of pneumonia. An autopsy revealed that atypical megakaryocytes increased in bone marrow and infiltrated into the spleen and liver. This case suggests that not only blasts but also megakaryocytes infiltrate into extramedullary organs in some cases of MDS.