Translocation t(3;4)(q26;q21) in myelodysplastic syndrome with megakaryoblastic proliferation.

A 74-year-old Japanese male with a 4-year history of refractory anemia with excess of blasts is reported here. Chromosome study revealed the bone marrow cells of this patient to contain a t(3;4)(q26;q21). Ultrastructural analysis of platelet peroxidase and immunocytochemical study using monoclonal antibody for platelet antigen revealed a large number of blasts in the bone marrow to be megakaryoblasts. Thus, this case was thought to be one of a myelodysplastic syndrome with excess of blasts including megakaryoblastic proliferation showing chromosome changes at 3q26 and 4q21. The relationship of the anomaly on the long arm of a chromosome #3, especially at band 3q26, to abnormal megakaryoblastic proliferation is discussed.